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  • Merge sort versus quick sort performance

    - by Giorgio
    I have implemented merge sort and quick sort using C (GCC 4.4.3 on Ubuntu 10.04 running on a 4 GB RAM laptop with an Intel DUO CPU at 2GHz) and I wanted to compare the performance of the two algorithms. The prototypes of the sorting functions are: void merge_sort(const char **lines, int start, int end); void quick_sort(const char **lines, int start, int end); i.e. both take an array of pointers to strings and sort the elements with index i : start <= i <= end. I have produced some files containing random strings with length on average 4.5 characters. The test files range from 100 lines to 10000000 lines. I was a bit surprised by the results because, even though I know that merge sort has complexity O(n log(n)) while quick sort is O(n^2), I have often read that on average quick sort should be as fast as merge sort. However, my results are the following. Up to 10000 strings, both algorithms perform equally well. For 10000 strings, both require about 0.007 seconds. For 100000 strings, merge sort is slightly faster with 0.095 s against 0.121 s. For 1000000 strings merge sort takes 1.287 s against 5.233 s of quick sort. For 5000000 strings merge sort takes 7.582 s against 118.240 s of quick sort. For 10000000 strings merge sort takes 16.305 s against 1202.918 s of quick sort. So my question is: are my results as expected, meaning that quick sort is comparable in speed to merge sort for small inputs but, as the size of the input data grows, the fact that its complexity is quadratic will become evident? Here is a sketch of what I did. In the merge sort implementation, the partitioning consists in calling merge sort recursively, i.e. merge_sort(lines, start, (start + end) / 2); merge_sort(lines, 1 + (start + end) / 2, end); Merging of the two sorted sub-array is performed by reading the data from the array lines and writing it to a global temporary array of pointers (this global array is allocate only once). After each merge the pointers are copied back to the original array. So the strings are stored once but I need twice as much memory for the pointers. For quick sort, the partition function chooses the last element of the array to sort as the pivot and scans the previous elements in one loop. After it has produced a partition of the type start ... {elements <= pivot} ... pivotIndex ... {elements > pivot} ... end it calls itself recursively: quick_sort(lines, start, pivotIndex - 1); quick_sort(lines, pivotIndex + 1, end); Note that this quick sort implementation sorts the array in-place and does not require additional memory, therefore it is more memory efficient than the merge sort implementation. So my question is: is there a better way to implement quick sort that is worthwhile trying out? If I improve the quick sort implementation and perform more tests on different data sets (computing the average of the running times on different data sets) can I expect a better performance of quick sort wrt merge sort? EDIT Thank you for your answers. My implementation is in-place and is based on the pseudo-code I have found on wikipedia in Section In-place version: function partition(array, 'left', 'right', 'pivotIndex') where I choose the last element in the range to be sorted as a pivot, i.e. pivotIndex := right. I have checked the code over and over again and it seems correct to me. In order to rule out the case that I am using the wrong implementation I have uploaded the source code on github (in case you would like to take a look at it). Your answers seem to suggest that I am using the wrong test data. I will look into it and try out different test data sets. I will report as soon as I have some results.

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  • How is counting sort a stable sort?

    - by eSKay
    Suppose my input is (a,b and c to distinguish between equal keys) 1 6a 8 3 6b 0 6c 4 My counting sort will save as (discarding the a,b and c info!!) 0(1) 1(1) 3(1) 4(1) 6(3) 8(1) which will give me the result 0 1 3 4 6 6 6 8 So, how is this stable sort? I am not sure how it is "maintaining the relative order of records with equal keys." Please explain.

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  • Stable ubuntu distribution for a broadcom bcm4313 wireless driver and an nvidia 630 graphics adapter

    - by Vivek Pradhan
    I have been trying to completely shift to ubuntu or a linux distro for almost 2 years now. I have tried all the ubuntu distros starting from 10.04 through 11.10, but there has always been some bugs with the display drivers or the wireless cards not being recognised and the additional drivers suggested from the ubuntu community not doing the trick always. I tried a lot to fix bugs, checked a lot of forums, launch pad, got some of them fixed, but could not really get a neat and complete ubuntu machine set up till now. Now I really like the whole open source community and the linux platform, my pc at home runs ubuntu 11.04 perfectly but there have been some glitches always with ubuntu on my laptop that has forced me to stick with windows only. Now I am currently on an hp dv6 laptop that has the broadcom bcm4313 wireless driver and the nvidia 630gtm graphics(optimus) driver. Now I tried to do some research on the support of these drivers in linux machines but could not get anywhere. So I would really appreciate if you guys could suggest some linux distro that I could use that has full support of these drivers or has stable bug fixes for these kind of issues. I tried precise pangolin (LTS) through a live CD but i still see a problem with wifi networks which is a little frustrating. Please help me find the perfect match for my laptop :P I would gladly provide any other information necessary.

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  • org-sort multi: date/time (?d ?t) | priority (?p) | title (?a)

    - by lawlist
    Is anyone aware of an org-sort function / modification that can refile / organize a group of TODO so that it sorts them by three (3) criteria: first sort by due date, second sort by priority, and third sort by by title of the task? EDIT: I believe that org-sort by deadline (?d) has a bug that cannot properly handle undated tasks. I am working on a workaround (i.e., moving the undated todo to a different heading before the deadline (?d) sort occurs), but perhaps the best thing to do would be to try and fix the original sorting function. Development of the workaround can be found in this thread (i.e., moving the undated tasks to a different heading in one fell swoop): How to automate org-refile for multiple todo EDIT: Apparently, the following code (ancient history) that I found on the internet was eventually modified and included as a part of org-sort-entries. Unfortunately, undated todo are not properly sorted when sorting by deadline -- i.e., they are mixed in with the dated todo. ;; multiple sort (defun org-sort-multi (&rest sort-types) "Multiple sorts on a certain level of an outline tree, or plain list items. SORT-TYPES is a list where each entry is either a character or a cons pair (BOOL . CHAR), where BOOL is whether or not to sort case-sensitively, and CHAR is one of the characters defined in `org-sort-entries-or-items'. Entries are applied in back to front order. Example: To sort first by TODO status, then by priority, then by date, then alphabetically (case-sensitive) use the following call: (org-sort-multi '(?d ?p ?t (t . ?a)))" (interactive) (dolist (x (nreverse sort-types)) (when (char-valid-p x) (setq x (cons nil x))) (condition-case nil (org-sort-entries (car x) (cdr x)) (error nil)))) ;; sort current level (defun lawlist-sort (&rest sort-types) "Sort the current org level. SORT-TYPES is a list where each entry is either a character or a cons pair (BOOL . CHAR), where BOOL is whether or not to sort case-sensitively, and CHAR is one of the characters defined in `org-sort-entries-or-items'. Entries are applied in back to front order. Defaults to \"?o ?p\" which is sorted by TODO status, then by priority" (interactive) (when (equal mode-name "Org") (let ((sort-types (or sort-types (if (or (org-entry-get nil "TODO") (org-entry-get nil "PRIORITY")) '(?d ?t ?p) ;; date, time, priority '((nil . ?a)))))) (save-excursion (outline-up-heading 1) (let ((start (point)) end) (while (and (not (bobp)) (not (eobp)) (<= (point) start)) (condition-case nil (outline-forward-same-level 1) (error (outline-up-heading 1)))) (unless (> (point) start) (goto-char (point-max))) (setq end (point)) (goto-char start) (apply 'org-sort-multi sort-types) (goto-char end) (when (eobp) (forward-line -1)) (when (looking-at "^\\s-*$") ;; (delete-line) ) (goto-char start) ;; (dotimes (x ) (org-cycle)) ))))) EDIT: Here is a more modern version of multi-sort, which is likely based upon further development of the above-code: (defun org-sort-all () (interactive) (save-excursion (goto-char (point-min)) (while (re-search-forward "^\* " nil t) (goto-char (match-beginning 0)) (condition-case err (progn (org-sort-entries t ?a) (org-sort-entries t ?p) (org-sort-entries t ?o) (forward-line)) (error nil))) (goto-char (point-min)) (while (re-search-forward "\* PROJECT " nil t) (goto-char (line-beginning-position)) (ignore-errors (org-sort-entries t ?a) (org-sort-entries t ?p) (org-sort-entries t ?o)) (forward-line)))) EDIT: The best option will be to fix sorting of deadlines (?d) so that undated todo are moved to the bottom of the outline, instead of mixed in with the dated todo. Here is an excerpt from the current org.el included within Emacs Trunk (as of July 1, 2013): (defun org-sort (with-case) "Call `org-sort-entries', `org-table-sort-lines' or `org-sort-list'. Optional argument WITH-CASE means sort case-sensitively." (interactive "P") (cond ((org-at-table-p) (org-call-with-arg 'org-table-sort-lines with-case)) ((org-at-item-p) (org-call-with-arg 'org-sort-list with-case)) (t (org-call-with-arg 'org-sort-entries with-case)))) (defun org-sort-remove-invisible (s) (remove-text-properties 0 (length s) org-rm-props s) (while (string-match org-bracket-link-regexp s) (setq s (replace-match (if (match-end 2) (match-string 3 s) (match-string 1 s)) t t s))) s) (defvar org-priority-regexp) ; defined later in the file (defvar org-after-sorting-entries-or-items-hook nil "Hook that is run after a bunch of entries or items have been sorted. When children are sorted, the cursor is in the parent line when this hook gets called. When a region or a plain list is sorted, the cursor will be in the first entry of the sorted region/list.") (defun org-sort-entries (&optional with-case sorting-type getkey-func compare-func property) "Sort entries on a certain level of an outline tree. If there is an active region, the entries in the region are sorted. Else, if the cursor is before the first entry, sort the top-level items. Else, the children of the entry at point are sorted. Sorting can be alphabetically, numerically, by date/time as given by a time stamp, by a property or by priority. The command prompts for the sorting type unless it has been given to the function through the SORTING-TYPE argument, which needs to be a character, \(?n ?N ?a ?A ?t ?T ?s ?S ?d ?D ?p ?P ?o ?O ?r ?R ?f ?F). Here is the precise meaning of each character: n Numerically, by converting the beginning of the entry/item to a number. a Alphabetically, ignoring the TODO keyword and the priority, if any. o By order of TODO keywords. t By date/time, either the first active time stamp in the entry, or, if none exist, by the first inactive one. s By the scheduled date/time. d By deadline date/time. c By creation time, which is assumed to be the first inactive time stamp at the beginning of a line. p By priority according to the cookie. r By the value of a property. Capital letters will reverse the sort order. If the SORTING-TYPE is ?f or ?F, then GETKEY-FUNC specifies a function to be called with point at the beginning of the record. It must return either a string or a number that should serve as the sorting key for that record. Comparing entries ignores case by default. However, with an optional argument WITH-CASE, the sorting considers case as well." (interactive "P") (let ((case-func (if with-case 'identity 'downcase)) (cmstr ;; The clock marker is lost when using `sort-subr', let's ;; store the clocking string. (when (equal (marker-buffer org-clock-marker) (current-buffer)) (save-excursion (goto-char org-clock-marker) (looking-back "^.*") (match-string-no-properties 0)))) start beg end stars re re2 txt what tmp) ;; Find beginning and end of region to sort (cond ((org-region-active-p) ;; we will sort the region (setq end (region-end) what "region") (goto-char (region-beginning)) (if (not (org-at-heading-p)) (outline-next-heading)) (setq start (point))) ((or (org-at-heading-p) (condition-case nil (progn (org-back-to-heading) t) (error nil))) ;; we will sort the children of the current headline (org-back-to-heading) (setq start (point) end (progn (org-end-of-subtree t t) (or (bolp) (insert "\n")) (org-back-over-empty-lines) (point)) what "children") (goto-char start) (show-subtree) (outline-next-heading)) (t ;; we will sort the top-level entries in this file (goto-char (point-min)) (or (org-at-heading-p) (outline-next-heading)) (setq start (point)) (goto-char (point-max)) (beginning-of-line 1) (when (looking-at ".*?\\S-") ;; File ends in a non-white line (end-of-line 1) (insert "\n")) (setq end (point-max)) (setq what "top-level") (goto-char start) (show-all))) (setq beg (point)) (if (>= beg end) (error "Nothing to sort")) (looking-at "\\(\\*+\\)") (setq stars (match-string 1) re (concat "^" (regexp-quote stars) " +") re2 (concat "^" (regexp-quote (substring stars 0 -1)) "[ \t\n]") txt (buffer-substring beg end)) (if (not (equal (substring txt -1) "\n")) (setq txt (concat txt "\n"))) (if (and (not (equal stars "*")) (string-match re2 txt)) (error "Region to sort contains a level above the first entry")) (unless sorting-type (message "Sort %s: [a]lpha [n]umeric [p]riority p[r]operty todo[o]rder [f]unc [t]ime [s]cheduled [d]eadline [c]reated A/N/P/R/O/F/T/S/D/C means reversed:" what) (setq sorting-type (read-char-exclusive)) (and (= (downcase sorting-type) ?f) (setq getkey-func (org-icompleting-read "Sort using function: " obarray 'fboundp t nil nil)) (setq getkey-func (intern getkey-func))) (and (= (downcase sorting-type) ?r) (setq property (org-icompleting-read "Property: " (mapcar 'list (org-buffer-property-keys t)) nil t)))) (message "Sorting entries...") (save-restriction (narrow-to-region start end) (let ((dcst (downcase sorting-type)) (case-fold-search nil) (now (current-time))) (sort-subr (/= dcst sorting-type) ;; This function moves to the beginning character of the "record" to ;; be sorted. (lambda nil (if (re-search-forward re nil t) (goto-char (match-beginning 0)) (goto-char (point-max)))) ;; This function moves to the last character of the "record" being ;; sorted. (lambda nil (save-match-data (condition-case nil (outline-forward-same-level 1) (error (goto-char (point-max)))))) ;; This function returns the value that gets sorted against. (lambda nil (cond ((= dcst ?n) (if (looking-at org-complex-heading-regexp) (string-to-number (match-string 4)) nil)) ((= dcst ?a) (if (looking-at org-complex-heading-regexp) (funcall case-func (match-string 4)) nil)) ((= dcst ?t) (let ((end (save-excursion (outline-next-heading) (point)))) (if (or (re-search-forward org-ts-regexp end t) (re-search-forward org-ts-regexp-both end t)) (org-time-string-to-seconds (match-string 0)) (org-float-time now)))) ((= dcst ?c) (let ((end (save-excursion (outline-next-heading) (point)))) (if (re-search-forward (concat "^[ \t]*\\[" org-ts-regexp1 "\\]") end t) (org-time-string-to-seconds (match-string 0)) (org-float-time now)))) ((= dcst ?s) (let ((end (save-excursion (outline-next-heading) (point)))) (if (re-search-forward org-scheduled-time-regexp end t) (org-time-string-to-seconds (match-string 1)) (org-float-time now)))) ((= dcst ?d) (let ((end (save-excursion (outline-next-heading) (point)))) (if (re-search-forward org-deadline-time-regexp end t) (org-time-string-to-seconds (match-string 1)) (org-float-time now)))) ((= dcst ?p) (if (re-search-forward org-priority-regexp (point-at-eol) t) (string-to-char (match-string 2)) org-default-priority)) ((= dcst ?r) (or (org-entry-get nil property) "")) ((= dcst ?o) (if (looking-at org-complex-heading-regexp) (- 9999 (length (member (match-string 2) org-todo-keywords-1))))) ((= dcst ?f) (if getkey-func (progn (setq tmp (funcall getkey-func)) (if (stringp tmp) (setq tmp (funcall case-func tmp))) tmp) (error "Invalid key function `%s'" getkey-func))) (t (error "Invalid sorting type `%c'" sorting-type)))) nil (cond ((= dcst ?a) 'string<) ((= dcst ?f) compare-func) ((member dcst '(?p ?t ?s ?d ?c)) '<))))) (run-hooks 'org-after-sorting-entries-or-items-hook) ;; Reset the clock marker if needed (when cmstr (save-excursion (goto-char start) (search-forward cmstr nil t) (move-marker org-clock-marker (point)))) (message "Sorting entries...done"))) (defun org-do-sort (table what &optional with-case sorting-type) "Sort TABLE of WHAT according to SORTING-TYPE. The user will be prompted for the SORTING-TYPE if the call to this function does not specify it. WHAT is only for the prompt, to indicate what is being sorted. The sorting key will be extracted from the car of the elements of the table. If WITH-CASE is non-nil, the sorting will be case-sensitive." (unless sorting-type (message "Sort %s: [a]lphabetic, [n]umeric, [t]ime. A/N/T means reversed:" what) (setq sorting-type (read-char-exclusive))) (let ((dcst (downcase sorting-type)) extractfun comparefun) ;; Define the appropriate functions (cond ((= dcst ?n) (setq extractfun 'string-to-number comparefun (if (= dcst sorting-type) '< '>))) ((= dcst ?a) (setq extractfun (if with-case (lambda(x) (org-sort-remove-invisible x)) (lambda(x) (downcase (org-sort-remove-invisible x)))) comparefun (if (= dcst sorting-type) 'string< (lambda (a b) (and (not (string< a b)) (not (string= a b))))))) ((= dcst ?t) (setq extractfun (lambda (x) (if (or (string-match org-ts-regexp x) (string-match org-ts-regexp-both x)) (org-float-time (org-time-string-to-time (match-string 0 x))) 0)) comparefun (if (= dcst sorting-type) '< '>))) (t (error "Invalid sorting type `%c'" sorting-type))) (sort (mapcar (lambda (x) (cons (funcall extractfun (car x)) (cdr x))) table) (lambda (a b) (funcall comparefun (car a) (car b))))))

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  • Java Alphabetize Algorithm Insertion sort vs Bubble Sort

    - by Chris Okyen
    I am supposed to "Develop a program that alphabetizes three strings. The program should allow the user to enter the three strings, and then display the strings in alphabetical order." It's instructed that I need to use the String library compareTo()/charAt()/toLowerCase() to make all the characters lowercase so the Lexicon comparison is also a alphabetical comparison. Input Pseudo Code: String input[3]; Scanner keyboard = new Scanner(System.in); System.out.println("Enter three strings: "); for(byte i = 0; i < 3; i++) input[i] = keyboard.next() The sorting would be Insertion Sort: 321 2 3 1 2 31 231 1 23 1 2 3 1 23 1 23 123 Bubble Sort 321 231 213 123 Which would be more efficient in this case? The bubble sort seems to be more efficient though they seem to have equal stats for worst best and avg case, but I read the Insertion Sort is quicker for small amounts of data like my case.

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  • Sort list using stl sort function

    - by Vlad
    I'm trying to sort a list (part of a class) in descending containg items of a struct but it doesn't compile(error: no match for 'operator-' in '__last - __first'): sort(Result.poly.begin(), Result.poly.end(), SortDescending()); And here's SortDescending: struct SortDescending { bool operator()(const term& t1, const term& t2) { return t2.pow < t1.pow; } }; Can anyone tell me what's wrong? Thanks!

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  • Using selection sort in java to sort floats

    - by user334046
    Hey, I need to sort an array list of class house by a float field in a certain range. This is my code for the selection sort: public ArrayList<House> sortPrice(ArrayList<House> x,float y, float z){ ArrayList<House> xcopy = new ArrayList<House>(); for(int i = 0; i<x.size(); i++){ if(x.get(i).myPriceIsLessThanOrEqualTo(z) && x.get(i).myPriceIsGreaterThanOrEqualTo(y)){ xcopy.add(x.get(i)); } } ArrayList<House> price= new ArrayList<House>(); while(xcopy.size()>0){ House min = xcopy.get(0); for(int i = 1; i < xcopy.size();i++){ House current = xcopy.get(i); if (current.myPriceIsGreaterThanOrEqualTo(min.getPrice())){ min = current; } } price.add(min); xcopy.remove(min); } return price; } Here is what the house class looks like: public class House { private int numBedRs; private int sqft; private float numBathRs; private float price; private static int idNumOfMostRecentHouse = 0; private int id; public House(int bed,int ft, float bath, float price){ sqft = ft; numBathRs = bath; numBedRs = bed; this.price = price; idNumOfMostRecentHouse++; id = idNumOfMostRecentHouse; } public boolean myPriceIsLessThanOrEqualTo(float y){ if(Math.abs(price - y)<0.000001){ return true; } return false; } public boolean myPriceIsGreaterThanOrEqualTo(float b){ if(Math.abs(b-price)>0.0000001){ return true; } return false; } When i call looking for houses in range 260000.50 to 300000 I only get houses that are at the top of the range even though I have a lower value at 270000. Can someone help?

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  • unexpected result from gnu sort

    - by funkycat
    when I try to sort the following text file 'input': test1 3 test3 2 test 4 with the command sort input the output is exactly the input. Here is the output of od -bc input : 0000000 164 145 163 164 061 011 063 012 164 145 163 164 063 011 062 012 t e s t 1 \t 3 \n t e s t 3 \t 2 \n 0000020 164 145 163 164 011 064 012 t e s t \t 4 \n 0000027 It's just a tab separated file with two columns. When I do sort -k 2 The output changes to test3 2 test1 3 test 4 which is what I would expect. But if I do sort -k 1 nothing changes with respect to the input, whereas I would expect 'test' to sort before 'test1'. Finally, if I do cat input | cut -f 1 | sort I get test test1 test3 as expected. Is there a logical explanation for this? What exactly is sort supposed to do by default, something like: sort -k 1 ? My version of sort: sort (GNU coreutils) 7.4

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  • How to UNIX sort by one column only?

    - by ssn
    I know that the -k option for the Unix sort allow us to sort by a specific column and all of the following. For instance, given the input file: 2 3 2 2 1 2 2 1 1 1 Using sort -n -k 1, I get an output sorted by the 1st column and then by the 2nd: 1 1 1 2 2 1 2 2 2 3 However, I want to keep the 2nd column ordering, like this: 1 2 1 1 2 3 2 2 2 1 Is this possible with the sort command?

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  • Cannot install stable Xbox 360 driver

    - by Mohd Arafat Hossain
    When I type in sudo add-apt-repository ppa:grumbel/ppa sudo apt-get update sudo apt-get install xboxdrv then when I go to install the stable driver like this sudo apt-get install xboxdrv-stable I get this mohd-arafat-hossain@TUD:~$ sudo apt-get install xboxdrv-stable [sudo] password for the-ubuntu-documentary: Reading package lists... Done Building dependency tree Reading state information... Done E: Unable to locate package xboxdrv-stable

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  • function to org-sort by three (3) criteria: due date / priority / title

    - by lawlist
    Is anyone aware of an org-sort function / modification that can refile / organize a group of TODO so that it sorts them by three (3) criteria: first sort by due date, second sort by priority, and third sort by by title of the task? EDIT: If anyone can please help me to modify this so that undated TODO are sorted last, that would be greatly appreciated -- at the present time, undated TODO are not being sorted: ;; multiple sort (defun org-sort-multi (&rest sort-types) "Multiple sorts on a certain level of an outline tree, or plain list items. SORT-TYPES is a list where each entry is either a character or a cons pair (BOOL . CHAR), where BOOL is whether or not to sort case-sensitively, and CHAR is one of the characters defined in `org-sort-entries-or-items'. Entries are applied in back to front order. Example: To sort first by TODO status, then by priority, then by date, then alphabetically (case-sensitive) use the following call: (org-sort-multi '(?d ?p ?t (t . ?a)))" (interactive) (dolist (x (nreverse sort-types)) (when (char-valid-p x) (setq x (cons nil x))) (condition-case nil (org-sort-entries (car x) (cdr x)) (error nil)))) ;; sort current level (defun lawlist-sort (&rest sort-types) "Sort the current org level. SORT-TYPES is a list where each entry is either a character or a cons pair (BOOL . CHAR), where BOOL is whether or not to sort case-sensitively, and CHAR is one of the characters defined in `org-sort-entries-or-items'. Entries are applied in back to front order. Defaults to \"?o ?p\" which is sorted by TODO status, then by priority" (interactive) (when (equal mode-name "Org") (let ((sort-types (or sort-types (if (or (org-entry-get nil "TODO") (org-entry-get nil "PRIORITY")) '(?d ?t ?p) ;; date, time, priority '((nil . ?a)))))) (save-excursion (outline-up-heading 1) (let ((start (point)) end) (while (and (not (bobp)) (not (eobp)) (<= (point) start)) (condition-case nil (outline-forward-same-level 1) (error (outline-up-heading 1)))) (unless (> (point) start) (goto-char (point-max))) (setq end (point)) (goto-char start) (apply 'org-sort-multi sort-types) (goto-char end) (when (eobp) (forward-line -1)) (when (looking-at "^\\s-*$") ;; (delete-line) ) (goto-char start) ;; (dotimes (x ) (org-cycle)) )))))

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  • Stable separation for two classes of elements in an array

    - by AndreyT
    Consider the following problem. We are given an array of elements belonging to one two classes: either red or blue. We have to rearrange the elements of the array so that all blue elements come first (and all red elements follow). The rearrangement must be done is stable fashion, meaning that the relative order of blue elements must be preserved (same for red ones). Is there a clever algorithm that would perform the above rearrangement in-place? A non-in place solution is, of course, straightforward. An obvious in-place solution would be to apply any stable sorting algorithm to the array. However, using a full-fledged sorting algorithm on an array intuitively feels like an overkill, especially taking into account the fact that we are only dealing with two classes of elements. Any ideas greatly appreciated.

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  • First Stable Version of Opera 15 has been Released

    - by Akemi Iwaya
    Opera has just released the first stable version of their revamped browser and will be proceeding at a rapid pace going forward. There is also news concerning the three development streams they will maintain along with news of an update for the older 12.x series for those who are not ready to update to 15.x just yet. The day is full of good news for Opera users whether they have already switched to the new Blink/Webkit Engine version or are still using the older Presto Engine version. First, news of the new development streams… Opera has released details outlining their three new release streams: Opera (Stable) – Released every couple of weeks, this is the most solid version, ready for mission-critical daily use. Opera Next – Updated more frequently than Stable, this is the feature-complete candidate for the Stable version. While it should be ready for daily use, you can expect some bugs there. Opera Developer – A bleeding edge version, you can expect a lot of fancy stuff there; however, some nasty bugs might also appear from time to time. From the Opera Desktop Team blog post: When you install Opera from a particular stream, your installation will stick to it, so Opera Stable will be always updated to Opera Stable, Opera Next to Opera Next and so on. You can choose for yourself which stream is the best for you. You can even follow a couple of them at the same time! Of particular interest is the announcement of continued development for the 12.x series. A new version (12.16) is due to be released soon to help keep the older series up to date and secure while the transition process from 12.x to 15.x continues.    

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  • Array.sort Sorting Stability in Different Browsers

    - by Boushley
    What is the stability of Array.sort in different browsers. I know that the ECMA Script specification does not specify which algorithm to use, nor does it specify whether the sort should be stable. I've found this information on for Firefox https://developer.mozilla.org/en/Core_JavaScript_1.5_Reference/Global_Objects/Array/sort which specifies that firefox uses a stable sort. Does anyone know about IE 6/7/8, Chrome, Safari?

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  • Sort files in folders by size (Mac OS X)

    - by Željko Filipin
    I have a folder full of folders and files. I want to sort files by size (so I could remove the largest files). I know how to do that in Windows Explorer, but I can not find a way to do it in Mac OS X Finder. Windows 2003: open folder in Windows Explorer click button Search leave Search for files or folders named and Containing text text fields empty click button Search Now sort by size Is there a way to do something like this in Finder on Mac OS X?

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  • Merging and sorting multiple files with "sort"

    - by NewbiZ
    Hello, I have a bunch of text logfiles in the following format: ID (17 characters) Timestamp (14 characters YYYYmmddHHMMSS e.g. "20060210100040" -> 2006/02/10 10:00:40) Random data (? characters) end of line The files are already sorted by timestamp. I need to get 1 log file with all the logs from multiple logs files, sorted by timestamp. Note that the log files are really huge, around 3-4G each (and there are dozens of them) I tried the following command: sort -s -m -t '|' -k1n,1n +17 -o data_sort.txt *.TXT Here is how I ended up with this command: -s : don't bother with tie results -m : merge all logs files -t '|' : there is no | in my logs, so the whole line should be field 1 -k1n,1n: sort on the first field as a numeric value +17 : the timestamp starts at index 17 -o : output file Actually... it fails miserably. The output file data_sort.txt is just the concatenation of all files, not sorted at all :( I would greatly appreciate if anyone could provide any help on this problem! Thanks

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  • List.Sort in C#: comparer being called with null object

    - by cbp
    I am getting strange behaviour using the built-in C# List.Sort function with a custom comparer. For some reason it sometimes calls the comparer class's Compare method with a null object as one of the parameters. But if I check the list with the debugger there are no null objects in the collection. My comparer class looks like this: public class DelegateToComparer<T> : IComparer<T> { private readonly Func<T,T,int> _comparer; public int Compare(T x, T y) { return _comparer(x, y); } public DelegateToComparer(Func<T, T, int> comparer) { _comparer = comparer; } } This allows a delegate to be passed to the List.Sort method, like this: mylist.Sort(new DelegateToComparer<MyClass>( (x, y) => { return x.SomeProp.CompareTo(y.SomeProp); }); So the above delegate will throw a null reference exception for the x parameter, even though no elements of mylist are null. UPDATE: Yes I am absolutely sure that it is parameter x throwing the null reference exception! UPDATE: Instead of using the framework's List.Sort method, I tried a custom sort method (i.e. new BubbleSort().Sort(mylist)) and the problem went away. As I suspected, the List.Sort method passes null to the comparer for some reason.

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  • Template Sort In C++

    - by wdow88
    Hey all, I'm trying to write a sort function but am having trouble figuring out how to initialize a value, and making this function work as a generic template. The sort works by: Find a pair =(ii,jj)= with a minimum value = ii+jj = such at A[ii]A[jj] If such a pair exists, then swap A[ii] and A[jj] else break; The function I have written is as follows: template <typename T> void sort(T *A, int size) { T min =453; T temp=0; bool swapper = true; while(swapper) { swapper = false; int index1 = 0, index2 = 0; for (int ii = 0; ii < size-1; ii++){ for (int jj = ii + 1; jj < size; jj++){ if((min >= (A[ii]+A[jj])) && (A[ii] > A[jj])){ min = (A[ii]+A[jj]); index1 = ii; index2 = jj; swapper = true; } } } if (!swapper) return; else { temp = A[index1]; A[index1] = A[index2]; A[index2] = temp; sort(A,size); } } } This function will successfully sort an array of integers, but not an array of chars. I do not know how to properly initialize the min value for the start of the comparison. I tried initializing the value by simply adding the first two elements of the array together (min = A[0] + A[1]), but it looks to me like for this algorithm it will fail. I know this is sort of a strange type of sort, but it is practice for a test, so thanks for any input.

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  • How do I force folder view sort order to not ignore special characters?

    - by Jason Hartley
    I have many folders in my home directory that have names that begin with special characters such as _OLD_500GB_HD or !FolderIWantToSeeAtTheTop, but for some reason these folders are sorted according to their first alphanumeric character rather than the leading special character. So how can I force the folder to not ignore the special character, or how else can I make the sort view organize certain folders at the top or bottom of the sort? Thanks.

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  • How do I sort by human readable sizes numerically?

    - by UAdapter
    for example I have command that shows how much space folder takes du folder | sort -n it works great, however I would like to have human readable form du -h folder however if I do that than I cannot sort it as numeric. How to join du folder and du -h folder to see output sorted as du folder, but with first column from du -h folder P.S. this is just an example. this technique might be very useful for me (if its possible)

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  • How does Batcher Merge work at a high level?

    - by Mike
    I'm trying to grasp the concept of a Batcher Sort. However, most resources I've found online focus on proof entirely or on low-level pseudocode. Before I look at proofs, I'd like to understand how Batcher Sort works. Can someone give a high level overview of how Batcher Sort works(particularly the merge) without overly verbose pseudocode(I want to get the idea behind the Batcher Sort, not implement it)? Thanks!

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  • Java - Collections.sort() performance

    - by msr
    Hello, Im using Collections.sort() to sort a LinkedList whose elements implements Comparable interface, so they are sorted in a natural order. In the javadoc documentation its said this method uses mergesort algorithm wich has n*log(n) performance. My question is if there is a more efficient algorithm to sort my LinkedList? The size of that list could be very high and sort will be also very frequent. Thanks!

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  • ICollectionView.SortDescriptions sort does not work if underlying DataTable has zero rows

    - by BigBlondeViking
    We have a WPF app that has a DataGrid inside a ListView. private DataTable table_; We do a bunch or dynamic column generation ( depending on the report we are showing ) We then do the a query and fill the DataTable row by row, this query may or may not have data.( not the problem, an empty grid is expected ) We set the ListView's ItemsSource to the DefaultView of the DataTable. lv.ItemsSource = table_.DefaultView; We then (looking at the user's pass usage of the app, set the sort on the column) Sort Method below: private void Sort(string sortBy, ListSortDirection direction) { ICollectionView dataView = CollectionViewSource.GetDefaultView(lv.ItemsSource); dataView.SortDescriptions.Clear(); var sd = new SortDescription(sortBy, direction); dataView.SortDescriptions.Add(sd); dataView.Refresh(); } In the Zero DataTable rows scenario, the sort does not "hold"? and if we dynamically add rows they will not be in sorted order. If the DataTable has at-least 1 row when the sort is applied, and we dynamically add rows to the DataTable, the rows com in sorted correctly. I have built a standalone app that replicate this... It is an annoyance and I can add a check to see if the DataTable was empty, and re-apply the sort... Anyone know whats going on here, and am I doing something wrong? FYI: What we based this off if comes from the MSDN as well: http://msdn.microsoft.com/en-us/library/ms745786.aspx

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  • Sort on DataView does not work if DataTable has zero rows

    - by BigBlondeViking
    We have a WPF app that has a DataGrid insode a ListView. private DataTable table_; We do a bunch or dynamic column generation ( depending on the report we are showing ) We then do the a query and fill the DataTable row by row, this query may or may not have data.( not the problem, an empty grid is expected ) We set the ListView's ItemsSource to the DefaultView of the DataTable. lv.ItemsSource = table_.DefaultView; We then (looking at the user's pass usage of the app, set the sort on the column) Sort Method below: private void Sort(string sortBy, ListSortDirection direction) { var dataView = CollectionViewSource.GetDefaultView(lv.ItemsSource); dataView.SortDescriptions.Clear(); var sd = new SortDescription(sortBy, direction); dataView.SortDescriptions.Add(sd); dataView.Refresh(); } In the Zero DataTable rows scenario, the sort does not "hold"? and if we dynamically add rows they will not be in sorted order. If the DataTable has at-least 1 row when the sort is applied, and we dynamically add rows to the DataTable, the rows com in sorted correctly. I have built a standalone app that replicate this... It is an annoyance and I can add a check to see if the DataTable was empty, and re-sort... Anyone know whats going on here, and am I doing something wrong? FYI: What we based this off if comes from the MSDN as well: http://msdn.microsoft.com/en-us/library/ms745786.aspx

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