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  • Invert linear linked list

    - by ArtWorkAD
    Hi, a linear linked list is a set of nodes. This is how a node is defined (to keep it easy we do not distinguish between node an list): class Node{ Object data; Node link; public Node(Object pData, Node pLink){ this.data = pData; this.link = pLink; } public String toString(){ if(this.link != null){ return this.data.toString() + this.link.toString(); }else{ return this.data.toString() ; } } public void inc(){ this.data = new Integer((Integer)this.data + 1); } public void lappend(Node list){ Node child = this.link; while(child != null){ child = child.link; } child.link = list; } public Node copy(){ if(this.link != null){ return new Node(new Integer((Integer)this.data), this.link.copy()); }else{ return new Node(new Integer((Integer)this.data), null); } } public Node invert(){ Node child = this.link; while(child != null){ child = child.link; } child.link = this;.... } } I am able to make a deep copy of the list. Now I want to invert the list so that the first node is the last and the last the first. The inverted list has to be a deep copy. I started developing the invert function but I am not sure. Any Ideas? Update: Maybe there is a recursive way since the linear linked list is a recursive data structure. I would take the first element, iterate through the list until I get to a node that has no child and append the first element, I would repeat this for the second, third....

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  • Sorting a Linked List [closed]

    - by Mohit Sehgal
    I want to sort a linked list. Here Node is class representing a node in a Linked List I have written a code to bubble sort a linked list. Program does not finishes execution. Kindly point out the mistakes. class Node { public: int data; public: Node *next; Node() { data=0;next=0; } Node(int d) { data=d; } void setData(int d) { data=d; } void print() { cout<<data<<endl; } bool operator==(Node n) { return this->data==n.data; } bool operator >(Node d) { if((this->data) > (d.data)) return true; return false; } }; class LList { public: int noOfNodes; Node *start;/*Header Node*/ LList() { start=new Node; noOfNodes=0;start=0; } void addAtFront(Node* n) { n->next=(start); start=n; noOfNodes++; } void addAtLast(Node* n) { Node *cur=(start); n->next=NULL; if(start==NULL) { start=n; noOfNodes++; return; } while(cur->next!=NULL) { cur=cur->next; } cur->next=n; noOfNodes++; } void addAtPos(Node *n,int pos) { if(pos==1) { addAtFront(n);return; } Node *cur=(start); Node *prev=NULL; int curPos=0; n->next=NULL; while(cur!=NULL) { curPos++; if(pos==curPos+1) { prev=cur; } if(pos==curPos) { n->next=cur; prev->next=n; break; } cur=cur->next; } noOfNodes++; } void removeFirst() { Node *del=start; start=start->next; delete del; noOfNodes--; return; } void removeLast() { Node *cur=start,*prev=NULL; while(cur->next!=NULL) { prev=cur; cur=cur->next; } prev->next=NULL; Node *del=cur->next; delete del; noOfNodes--; return; } void removeNodeAt(int pos) { if(pos<1) return; if(pos==1) { removeFirst();return;} int curPos=1; Node* cur=start->next; Node* prev=start; Node* del=NULL; while(curPos<pos&&cur!=NULL) { curPos++; if(curPos==pos) { del=cur; prev->next=cur->next; cur->next=NULL; delete del; noOfNodes--; break; } prev=prev->next; cur=cur->next; } } void removeNode(Node *d) { Node *cur=start; if(*d==*cur) { removeFirst();return; } cur=start->next; Node *prev=start,*del=NULL; while(cur!=NULL) { if(*cur==*d) { del=cur; prev->next=cur->next; delete del; noOfNodes--; break; } prev=prev->next; cur=cur->next; } } int getPosition(Node data) { int pos=0; Node *cur=(start); while(cur!=NULL) { pos++; if(*cur==data) { return pos; } cur=cur->next; } return -1;//not found } Node getNode(int pos) { if(pos<1) return -1;// not a valid position else if(pos>noOfNodes) return -1; // not a valid position Node *cur=(start); int curPos=0; while(cur!=NULL) { if(++curPos==pos) return *cur; cur=cur->next; } } void reverseList()//reverse the list { Node* cur=start->next; Node* d=NULL; Node* prev=start; while(cur!=NULL) { d=cur->next; cur->next=start; start=cur; prev->next=d; cur=d; } } void sortBubble() { Node *i=start,*j=start,*prev=NULL,*temp=NULL,*after=NULL; int count=noOfNodes-1;int icount=0; while(i->next!=NULL) { j=start; after=j->next; icount=0; while(++icount!=count) { if((*j)>(*after)) { temp=after->next; after->next=j; prev->next=j->next; j->next=temp; prev=after; after=j->next; } else{ prev=j; j=after; after=after->next; } } i=i->next; count--; } } void traverse() { Node *cur=(start); int c=0; while(cur!=NULL) { // cout<<"start"<<start; c++; cur->print(); cur=cur->next; } noOfNodes=c; } ~LList() { delete start; } }; int main() { int n; cin>>n; int d; LList list; Node *node; Node *temp=new Node(2123); for(int i=0;i<n;i++) { cin>>d; node=new Node(d); list.addAtLast(node); } list.addAtPos(temp,1); cout<<"traverse\n"; list.traverse(); temp=new Node(12); list.removeNode(temp); cout<<"12 removed"; list.traverse(); list.reverseList(); cout<<"\nreversed\n"; list.traverse(); cout<<"bubble sort\n"; list.sortBubble(); list.traverse(); getch(); delete node; return 0; }

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  • Test if single linked list is circular by traversing it only once

    - by user1589754
    I am a fresher and I was asked this question in a recent interview I gave. The question was --- By traversing each element of linked list just once find if the single linked list is circular at any point. To this I answered that we will store reference of each node while traversing the list in another linked list and for every node in the list being tested we will find if the reference exists in the list I am storing the references. The interviewer said that he needs a more optimized way to solve this problem. Can anyone please tell me what would be a more optimized method to solve this problem.

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  • Easiest way to merge a changed list to the master list

    - by Kiran Chandrashekhar
    I have a two lists of class object : private List<IntVector> UserData = new List<IntVector>(); private List<IntVector> EditData = new List<IntVector>(); UserData is the Master List and EditData is another list which would be used to add, delete, or modify the list. One of the class memeber is CaseNo which would not change for an IntVector. I have made changes in the EditData and would like to merge the changes to the UserData. Any idea how to do it ?

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  • Java - How to find count of items in a list in another list

    - by David Buckley
    Say I have two lists: List<String>products = new ArrayList<String>(); products.add("computer"); products.add("phone"); products.add("mouse"); products.add("keyboard"); List<String>cart = new ArrayList<String>(); cart.add("phone"); cart.add("monitor"); I need to find how many items in the cart list exist in the products list. For the lists above, the answer would be 1 (as phone is in products and cart). If the cart list was: List<String>cart = new ArrayList<String>(); cart.add("desk"); cart.add("chair"); The result would be 0. If cart contained computer, mouse, desk, chair, the result would be 2 (for computer and mouse). Is there something in the Apache Commons Collections or the Google Collections API? I've looked through them and see ways to get a bag count, but not from another list, although it's possible I'm missing something. Right now, the only way I can think of is to iterate over the cart items and see if products contains the individual item and keep a count. I can't use containsAll as I need the count (not a boolean), and that would fail if all items in cart didn't exist in the product list (which can happen). I'm using Java 1.6 if that matters.

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  • .net byte[] to List<List<Point>>

    - by user1112111
    Is is possible to convert a byte array back to a List<List<Point>> ? LE: I am saving the List<List<Point>> in a database BLOB field. When I retrieve it, I want to convert it back to a List<List<Point>>. So I have the byte[], but I cannot figure out how to convert it. How should the de/serialization look like ?

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  • Python - List of Lists Slicing Behavior

    - by Dan Dobint
    When I define a list and try to change a single item like this: list_of_lists = [['a', 'a', 'a'], ['a', 'a', 'a'], ['a', 'a', 'a']] list_of_lists[1][1] = 'b' for row in list_of_lists: print row It works as intended. But when I try to use list comprehension to create the list: row = ['a' for range in xrange(3)] list_of_lists = [row for range in xrange(3)] list_of_lists[1][1] = 'b' for row in list_of_lists: print row It results in an entire column of items in the list being changed. Why is this? How can I achieve the desired effect with list comprehension?

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  • Clip UITableView Cell's Separator

    - by Drewsmits
    I've been trying to build a view that looks similar to the "stocks" application (surprise). What I would like is to have the scroller bar outside of my rounded table view, shown in the image link below, but clip the cell separators. You can see how they overlap the scroller bar, which is annoying. I can't figure out how Apple put the scroller bar in a spot that looks like it is outside their table. Any ideas? (sorry, can't imbed images yet because I'm a new user). Scroller Problem Image

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  • Create unordered list tree menu from data stored in an table with the adjacency list model...php

    - by Ronedog
    I need to create a tree menu of "nth" subcategories. I settled on using the adjacency list model for my table structure, because I won't be updating this table very much and this seemed the easiest to implement for my use. I want to style the output using "ul" and "li" tags...I already have a css and jquery solution to do the styling. My problem comes from pulling the data out of the database and using a recursive function via PHP to build the list ... the list is a concatenated string that gets parsed to build the tree. I'm really having a hard time getting the closing "ul" and "li" tags to line up just where they need to be. Is this the best way to do this? Are there other better ways using arrays or something like that to do this? Any examples you can point me to of "best practices" for building a list like this will be appreciated. Thanks.

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  • Update a list from another list

    - by Langali
    I have a list of users in local store that I need to update from a remote list of users every once in a while. Basically: If a remote user already exists locally, update its fields. If a remote user doesn't already exist locally, add the user. If a local user doesn't appear in the remote list, deactivate or delete. If a local user also appears in the remote list, update its fields. Just a simple case of syncing the local list. Is there a better way to do this in pure Java than the following? I feel gross looking at my own code. public class User { Integer id; String email; boolean active; //Getters and Setters....... public User(Integer id, String email, boolean active) { this.id = id; this.email = email; this.active = active; } @Override public boolean equals(Object other) { boolean result = false; if (other instanceof User) { User that = (User) other; result = (this.getId() == that.getId()); } return result; } } public static void main(String[] args) { //From 3rd party List<User> remoteUsers = getRemoteUsers(); //From Local store List<User> localUsers =getLocalUsers(); for (User remoteUser : remoteUsers) { boolean found = false; for (User localUser : localUsers) { if (remoteUser.equals(localUser)) { found = true; localUser.setActive(remoteUser.isActive()); localUser.setEmail(remoteUser.getEmail()); //update } break; } if (!found) { User user = new User(remoteUser.getId(), remoteUser.getEmail(), remoteUser.isActive()); //Save } } for(User localUser : localUsers ) { boolean found = false; for(User remoteUser : remoteUsers) { if(localUser.equals(remoteUser)) { found = true; localUser.setActive(remoteUser.isActive()); localUser.setEmail(remoteUser.getEmail()); //Update } break; } if(!found) { localUser.setActive(false); // Deactivate } } }

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  • Parallel.For maintain input list order on output list

    - by romeozor
    I'd like some input on keeping the order of a list during heavy-duty operations that I decided to try to do in a parallel manner to see if it boosts performance. (It did!) I came up with a solution, but since this was my first attempt at anything parallel, I'd need someone to slap my hands if I did something very stupid. There's a query that returns a list of card owners, sorted by name, then by date of birth. This needs to be rendered in a table on a web page (ASP.Net WebForms). The original coder decided he would construct the table cell-by-cell (TableCell), add them to rows (TableRow), then each row to the table. So no GridView, allegedly its performance is bad, but the performance was very poor regardless :). The database query returns in no time, the most time is spent on looping through the results and adding table cells etc. I made the following method to maintain the original order of the list: private TableRow[] ComposeRows(List<CardHolder> queryResult) { int queryElementsCount = queryResult.Count(); // array with the query's size var rowArray = new TableRow[queryElementsCount]; Parallel.For(0, queryElementsCount, i => { var row = new TableRow(); var cell = new TableCell(); // various operations, including simple ones such as: cell.Text = queryResult[i].Name; row.Cells.Add(cell); // here I'm adding the current item to it's original index // to maintain order in the output list rowArray[i] = row; }); return rowArray; } So as you can see, because I'm returning a very different type of data (List<CardHolder> -> TableRow[]), I can't just simply omit the ordering from the original query to do it after the operations. Also, I also thought it would be a good idea to Dispose() the objects at the end of each loop, because the query can return a huge list and letting cell and row objects pile up in the heap could impact performance.(?) How badly did I do? Does anyone have a better solution in case mine is flawed?

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  • dpkg: warning: files list file for package 'x' missing

    - by Mark
    I get this warning for several packages every time I install any package or perform apt-get upgrade. Not sure what is causing it; it's a fresh Debian install on my OpenVZ server and I haven't changed any dpkg settings. Here's an example: root@debian:~# apt-get install cowsay Reading package lists... Done Building dependency tree Reading state information... Done Suggested packages: filters The following NEW packages will be installed: cowsay 0 upgraded, 1 newly installed, 0 to remove and 0 not upgraded. Need to get 21.9 kB of archives. After this operation, 91.1 kB of additional disk space will be used. Get:1 http://ftp.us.debian.org/debian/ unstable/main cowsay all 3.03+dfsg1-4 [21.9 kB] Fetched 21.9 kB in 0s (70.2 kB/s) Selecting previously unselected package cowsay. dpkg: warning: files list file for package 'libssh2-1:amd64' missing; assuming package has no files currently installed dpkg: warning: files list file for package 'libkrb5-3:amd64' missing; assuming package has no files currently installed dpkg: warning: files list file for package 'libwrap0:amd64' missing; assuming package has no files currently installed dpkg: warning: files list file for package 'libcap2:amd64' missing; assuming package has no files currently installed dpkg: warning: files list file for package 'libpam-ck-connector:amd64' missing; assuming package has no files currently installed dpkg: warning: files list file for package 'libc6:amd64' missing; assuming package has no files currently installed dpkg: warning: files list file for package 'libtalloc2:amd64' missing; assuming package has no files currently installed dpkg: warning: files list file for package 'libselinux1:amd64' missing; assuming package has no files currently installed dpkg: warning: files list file for package 'libp11-kit0:amd64' missing; assuming package has no files currently installed dpkg: warning: files list file for package 'libavahi-client3:amd64' missing; assuming package has no files currently installed dpkg: warning: files list file for package 'libbz2-1.0:amd64' missing; assuming package has no files currently installed dpkg: warning: files list file for package 'libpcre3:amd64' missing; assuming package has no files currently installed dpkg: warning: files list file for package 'libgpm2:amd64' missing; assuming package has no files currently installed dpkg: warning: files list file for package 'libgnutls26:amd64' missing; assuming package has no files currently installed dpkg: warning: files list file for package 'libavahi-common3:amd64' missing; assuming package has no files currently installed dpkg: warning: files list file for package 'libcroco3:amd64' missing; assuming package has no files currently installed dpkg: warning: files list file for package 'liblzma5:amd64' missing; assuming package has no files currently installed dpkg: warning: files list file for package 'libpaper1:amd64' missing; assuming package has no files currently installed dpkg: warning: files list file for package 'libsensors4:amd64' missing; assuming package has no files currently installed dpkg: warning: files list file for package 'libbsd0:amd64' missing; assuming package has no files currently installed dpkg: warning: files list file for package 'libavahi-common-data:amd64' missing; assuming package has no files currently installed dpkg: warning: files list file for package 'libss2:amd64' missing; assuming package has no files currently installed dpkg: warning: files list file for package 'libblkid1:amd64' missing; assuming package has no files currently installed dpkg: warning: files list file for package 'libslang2:amd64' missing; assuming package has no files currently installed dpkg: warning: files list file for package 'libacl1:amd64' missing; assuming package has no files currently installed dpkg: warning: files list file for package 'libcomerr2:amd64' missing; assuming package has no files currently installed dpkg: warning: files list file for package 'libkrb5support0:amd64' missing; assuming package has no files currently installed dpkg: warning: files list file for package 'e2fslibs:amd64' missing; assuming package has no files currently installed dpkg: warning: files list file for package 'librtmp0:amd64' missing; assuming package has no files currently installed dpkg: warning: files list file for package 'libidn11:amd64' missing; assuming package has no files currently installed dpkg: warning: files list file for package 'libpcap0.8:amd64' missing; assuming package has no files currently installed dpkg: warning: files list file for package 'libattr1:amd64' missing; assuming package has no files currently installed dpkg: warning: files list file for package 'libdevmapper1.02.1:amd64' missing; assuming package has no files currently installed dpkg: warning: files list file for package 'odbcinst1debian2:amd64' missing; assuming package has no files currently installed dpkg: warning: files list file for package 'libexpat1:amd64' missing; assuming package has no files currently installed dpkg: warning: files list file for package 'libltdl7:amd64' missing; assuming package has no files currently installed dpkg: warning: files list file for package 'libkeyutils1:amd64' missing; assuming package has no files currently installed dpkg: warning: files list file for package 'libcups2:amd64' missing; assuming package has no files currently installed dpkg: warning: files list file for package 'libsqlite3-0:amd64' missing; assuming package has no files currently installed dpkg: warning: files list file for package 'libck-connector0:amd64' missing; assuming package has no files currently installed dpkg: warning: files list file for package 'zlib1g:amd64' missing; assuming package has no files currently installed dpkg: warning: files list file for package 'libnl1:amd64' missing; assuming package has no files currently installed dpkg: warning: files list file for package 'libfontconfig1:amd64' missing; assuming package has no files currently installed dpkg: warning: files list file for package 'libudev0:amd64' missing; assuming package has no files currently installed dpkg: warning: files list file for package 'libsepol1:amd64' missing; assuming package has no files currently installed dpkg: warning: files list file for package 'libmagic1:amd64' missing; assuming package has no files currently installed dpkg: warning: files list file for package 'libk5crypto3:amd64' missing; assuming package has no files currently installed dpkg: warning: files list file for package 'libunistring0:amd64' missing; assuming package has no files currently installed dpkg: warning: files list file for package 'libgpg-error0:amd64' missing; assuming package has no files currently installed dpkg: warning: files list file for package 'libusb-0.1-4:amd64' missing; assuming package has no files currently installed dpkg: warning: files list file for package 'libpam0g:amd64' missing; assuming package has no files currently installed dpkg: warning: files list file for package 'libpopt0:amd64' missing; assuming package has no files currently installed dpkg: warning: files list file for package 'libgssapi-krb5-2:amd64' missing; assuming package has no files currently installed dpkg: warning: files list file for package 'libgeoip1:amd64' missing; assuming package has no files currently installed dpkg: warning: files list file for package 'libcurl3-gnutls:amd64' missing; assuming package has no files currently installed dpkg: warning: files list file for package 'libtasn1-3:amd64' missing; assuming package has no files currently installed dpkg: warning: files list file for package 'libuuid1:amd64' missing; assuming package has no files currently installed dpkg: warning: files list file for package 'libgcrypt11:amd64' missing; assuming package has no files currently installed dpkg: warning: files list file for package 'libgdbm3:amd64' missing; assuming package has no files currently installed dpkg: warning: files list file for package 'libdbus-1-3:amd64' missing; assuming package has no files currently installed dpkg: warning: files list file for package 'libsysfs2:amd64' missing; assuming package has no files currently installed dpkg: warning: files list file for package 'libfreetype6:amd64' missing; assuming package has no files currently installed (Reading database ... 21908 files and directories currently installed.) Unpacking cowsay (from .../cowsay_3.03+dfsg1-4_all.deb) ... Processing triggers for man-db ... Setting up cowsay (3.03+dfsg1-4) ... root@debian:~# Everything works fine, but these warning messages are pretty annoying. Does anyone know how I can fix this?

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  • Python list comprehension to return edge values of a list

    - by mvid
    If I have a list in python such as: stuff = [1, 2, 3, 4, 5, 6, 7, 8, 9] with length n (in this case 9) and I am interested in creating lists of length n/2 (in this case 4). I want all possible sets of n/2 values in the original list, for example: [1, 2, 3, 4], [2, 3, 4, 5], ..., [9, 1, 2, 3] is there some list comprehension code I could use to iterate through the list and retrieve all of those sublists? I don't care about the order of the values within the lists, I am just trying to find a clever method of generating the lists.

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  • IE6 list issue - First list on page ignores horizontal margins

    - by user307922
    Hi Folks, I am creating a store in Magento and have a weird issue with IE6 and the ordered lists on my page. For some reason, IE6 ignores the horizontal margin on my first list. Not the first element in the list but the whole list. I have multiple list on the page. Here is a link to the offending page: http://byerofma.nexcess.net/products/pangean-furniture.html I have tried everything I can think of. Any ideas? Cheers, Chuck

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  • filtering elements from list of lists in Python?

    - by user248237
    I want to filter elements from a list of lists, and iterate over the elements of each element using a lambda. For example, given the list: a = [[1,2,3],[4,5,6]] suppose that I want to keep only elements where the sum of the list is greater than N. I tried writing: filter(lambda x, y, z: x + y + z >= N, a) but I get the error: <lambda>() takes exactly 3 arguments (1 given) How can I iterate while assigning values of each element to x, y, and z? Something like zip, but for arbitrarily long lists. thanks, p.s. I know I can write this using: filter(lambda x: sum(x)..., a) but that's not the point, imagine that these were not numbers but arbitrary elements and I wanted to assign their values to variable names.

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  • [C++] STL list - how to find a list element by its object fields

    - by Dominic Bou-Samra
    I have a list: list<Unit *> UnitCollection; containing Unit objects, which has an accessor like: bool Unit::isUnit(string uCode) { if(this->unitCode == uCode) return true; else return false; } How do I search my UnitCollection list by uCode and return the corresponding element (preferably it's index). I have looked at the find() method, but i'm not sure you can pass a boolean method in instead of a searched item parameter if that makes sense.

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  • List filtering: list comprehension vs. lambda + filter

    - by Agos
    I happened to find myself having a basic filtering need: I have a list and I have to filter it by an attribute of the items. My code looked like this: list = [i for i in list if i.attribute == value] But then i thought, wouldn't it be better to write it like this? filter(lambda x: x.attribute == value, list) It's more readable, and if needed for performance the lambda could be taken out to gain something. Question is: are there any caveats in using the second way? Any performance difference? Am I missing the Pythonic Way™ entirely and should do it in yet another way (such as using itemgetter instead of the lambda)? Thanks in advance

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  • List.clear() followed by List.add() not working.

    - by Vincent
    I have the following C# Class/Function: class Hand { private List<Card> myCards = new List<Card>(); public void sortBySuitValue() { IEnumerable<Card> query = from s in myCards orderby (int)s.suit, (int)s.value select s; myCards = new List<Card>(); myCards.AddRange(query); } } On a card Game. This works fine, however, I had trouble at first, instead of using myCards = new List(); to 'reset' myCards, I would use myCards.clear(), however, once I called the clear function, I would not be able to call myCards.add() or myCards.addRange(). The count would stay at zero. Is my current approach good? Is using LINQ to sort my cards good/bad?

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  • Mac OS X: How to change word separator characters?

    - by avetis.kazarian
    Depending on your system, the word separator characters change the way you can select/delete a word (e.g. by double clicking on it or using a key combination with your keyboard). The fact is that I hate the default behavior of OSX. For example: Take the following line of code: obj.attr1.innerAttr. If my cursor is at the end of the line and I press alt + backspace, it will delete everything and not just innerAttr. I only found some apps (like iTerm) which let you change the word separator characters. Is there a way to change it for the whole system?

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  • How can I get the path separator in Perl?

    - by ram
    In case of Java, we can get the path separator using System.getProperty("path.separator"); Is there a similar way in Perl? All I want to do is to find a dir, immediate sub directory. Say I am being given two arguments $a and $b; I am splitting the first one based on the path separator and joining it again except the last fragment and comparing with the second argument. The problem is my code has to be generic and for that I need to know whats the system dependent path separator is?

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  • Using a "white list" for extracting terms for Text Mining

    - by [email protected]
    In Part 1 of my post on "Generating cluster names from a document clustering model" (part 1, part 2, part 3), I showed how to build a clustering model from text documents using Oracle Data Miner, which automates preparing data for text mining. In this process we specified a custom stoplist and lexer and relied on Oracle Text to identify important terms.  However, there is an alternative approach, the white list, which uses a thesaurus object with the Oracle Text CTXRULE index to allow you to specify the important terms. INTRODUCTIONA stoplist is used to exclude, i.e., black list, specific words in your documents from being indexed. For example, words like a, if, and, or, and but normally add no value when text mining. Other words can also be excluded if they do not help to differentiate documents, e.g., the word Oracle is ubiquitous in the Oracle product literature. One problem with stoplists is determining which words to specify. This usually requires inspecting the terms that are extracted, manually identifying which ones you don't want, and then re-indexing the documents to determine if you missed any. Since a corpus of documents could contain thousands of words, this could be a tedious exercise. Moreover, since every word is considered as an individual token, a term excluded in one context may be needed to help identify a term in another context. For example, in our Oracle product literature example, the words "Oracle Data Mining" taken individually are not particular helpful. The term "Oracle" may be found in nearly all documents, as with the term "Data." The term "Mining" is more unique, but could also refer to the Mining industry. If we exclude "Oracle" and "Data" by specifying them in the stoplist, we lose valuable information. But it we include them, they may introduce too much noise. Still, when you have a broad vocabulary or don't have a list of specific terms of interest, you rely on the text engine to identify important terms, often by computing the term frequency - inverse document frequency metric. (This is effectively a weight associated with each term indicating its relative importance in a document within a collection of documents. We'll revisit this later.) The results using this technique is often quite valuable. As noted above, an alternative to the subtractive nature of the stoplist is to specify a white list, or a list of terms--perhaps multi-word--that we want to extract and use for data mining. The obvious downside to this approach is the need to specify the set of terms of interest. However, this may not be as daunting a task as it seems. For example, in a given domain (Oracle product literature), there is often a recognized glossary, or a list of keywords and phrases (Oracle product names, industry names, product categories, etc.). Being able to identify multi-word terms, e.g., "Oracle Data Mining" or "Customer Relationship Management" as a single token can greatly increase the quality of the data mining results. The remainder of this post and subsequent posts will focus on how to produce a dataset that contains white list terms, suitable for mining. CREATING A WHITE LIST We'll leverage the thesaurus capability of Oracle Text. Using a thesaurus, we create a set of rules that are in effect our mapping from single and multi-word terms to the tokens used to represent those terms. For example, "Oracle Data Mining" becomes "ORACLEDATAMINING." First, we'll create and populate a mapping table called my_term_token_map. All text has been converted to upper case and values in the TERM column are intended to be mapped to the token in the TOKEN column. TERM                                TOKEN DATA MINING                         DATAMINING ORACLE DATA MINING                  ORACLEDATAMINING 11G                                 ORACLE11G JAVA                                JAVA CRM                                 CRM CUSTOMER RELATIONSHIP MANAGEMENT    CRM ... Next, we'll create a thesaurus object my_thesaurus and a rules table my_thesaurus_rules: CTX_THES.CREATE_THESAURUS('my_thesaurus', FALSE); CREATE TABLE my_thesaurus_rules (main_term     VARCHAR2(100),                                  query_string  VARCHAR2(400)); We next populate the thesaurus object and rules table using the term token map. A cursor is defined over my_term_token_map. As we iterate over  the rows, we insert a synonym relationship 'SYN' into the thesaurus. We also insert into the table my_thesaurus_rules the main term, and the corresponding query string, which specifies synonyms for the token in the thesaurus. DECLARE   cursor c2 is     select token, term     from my_term_token_map; BEGIN   for r_c2 in c2 loop     CTX_THES.CREATE_RELATION('my_thesaurus',r_c2.token,'SYN',r_c2.term);     EXECUTE IMMEDIATE 'insert into my_thesaurus_rules values                        (:1,''SYN(' || r_c2.token || ', my_thesaurus)'')'     using r_c2.token;   end loop; END; We are effectively inserting the token to return and the corresponding query that will look up synonyms in our thesaurus into the my_thesaurus_rules table, for example:     'ORACLEDATAMINING'        SYN ('ORACLEDATAMINING', my_thesaurus)At this point, we create a CTXRULE index on the my_thesaurus_rules table: create index my_thesaurus_rules_idx on        my_thesaurus_rules(query_string)        indextype is ctxsys.ctxrule; In my next post, this index will be used to extract the tokens that match each of the rules specified. We'll then compute the tf-idf weights for each of the terms and create a nested table suitable for mining.

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  • Python 2.7 list of lists manipulation functionality

    - by user3688163
    I am trying to perform several operations on the myList list of lists below and am having some trouble figuring it out. I am very new to Python. myList = [ ['Issue Id','1.Completeness for OTC','Break',3275,33,33725102303,296384802,20140107], ['Issue Id','2.Validity check1 for OTC','Break',3308,0,34021487105,0,20140107], ['Issue Id','3.Validity check2 for OTC','Break',3308,0,34021487105,0,20140107], ['Issue Id','4.Completeness for RST','Break',73376,1,8.24931E+11,44690130,20140107], ['Issue Id','5.Validity check1 for RST','Break',73377,0,8.24976E+11,0,20140107], ['Liquidity','1. OTC - Null','Break',7821 0,2.28291E+11,0,20140110], ['Liquidity','2. OTC - Unmapped','Break',7778,43,2.27712E+11,579021732.8,20140110], ['Liquidity','3. RST - Null','Break',335120,0,1.01425E+12,0,20140110], ['Liquidity','4. RST - Unmapped','Break',334608,512,1.01351E+12,735465433.1,20140110], ['Liquidity','5. RST - Valid','Break',335120,0,1.01425E+12,0,20140110], ['Issue Id','1.Completeness for OTC','Break',3292,33,32397924450,306203929,20140110], ['Issue Id','2.Validity check1 for OTC','Break',3325,0,32704128379,0,20140110], ['Issue Id','3.Validity check2 for OTC','Break',3325,0,32704128379,0,20140110], ['Issue Id','4.Completeness for RST','Break',73594,3,8.5352E+11,69614602,20140110], ['Issue Id','5.Validity check1 for RST','Break',73597,0,8.5359E+11,0,20140110], ['Unlinked Silver ID','DQ','Break',3201318,176,20000000,54974.33386,20140101], ['Missing GCI','DQ','Break',3201336,158,68000000,49351.9588,20140101], ['Missing Book','DQ Break',3192720,8774,3001000000,2740595.484,20140101], ['Matured Trades','DQ','Break',3201006,488,1371000000,152428.8348,20140101], ['Illiquid Trades','1.Completeness Check for range','Break',43122,47,88597695671,54399061.43,20140107], ['Illiquid Trades','2.Completeness Check for non','Break',39033,0,79133622401,0,20140107] ] I am trying to get the result below but do not know how to do so: newList = [ ['Issue Id','1.Completeness for OTC:2.Validity check1 for OTC:3.Validity check2 for OTC','Break',3275,33,33725102303,296384802,20140107], ['Issue Id','4.Completeness for RST:5.Validity check1 for RST','Break',73376,1,8.24931E+11,44690130,20140107], ['Liquidity','1. OTC - Null','Break:2. OTC - Unmapped','Break',7821 0,2.28291E+11,0,20140110], ['Liquidity','3. RST - Null:4. RST - Unmapped:5. RST - Valid','Break',335120,0,1.01425E+12,0,20140110], ['Issue Id','1.Completeness for OTC:2.Validity check1 for OTC:3.Validity check2 for OTC','Break',3292,33,32397924450,306203929,20140110], ['Issue Id','4.Completeness for RST:5. RST - Valid','Break',73594,3,8.5352E+11,69614602,20140110], ['Unlinked Silver ID','DQ','Break',3201318,176,20000000,54974.33386,20140101], ['Missing GCI','DQ','Break',3201336,158,68000000,49351.9588,20140101], ['Missing Book','DQ Break',3192720,8774,3001000000,2740595.484,20140101], ['Matured Trades','DQ','Break',3201006,488,1371000000,152428.8348,20140101], ['Illiquid Trades','1.Completeness Check for range','Break',43122,47,88597695671,54399061.43,20140107], ['Illiquid Trades','2.Completeness Check for non','Break',39033,0,79133622401,0,20140107] ] Rules to create newList. Create a new list in the newList list of lists if the values in the lists meet the following conditions: multiple lists that match on `myList[i][0]` and `myList[i][7]` but with have (1) sums of `myList[i][3]` and `myList[i][4]` and (2) sums of `myList[i][5]` and `myList[i][6]` that are different from each other are just listed as is in newList if multiple lists match on both `myList[i][0]` (this is the type) and `myList[i][7]` (this is the date) are the same then create a new list for each set of lists with mathcing `myList[i][0]` and `myList[i][7]` that have (1) sums of `myList[i][3]` and `myList[i][4]` and (2) sums of `myList[i][5]` and `myList[i][6]` that are different from the other lists with mathcing `myList[i][0]` and `myList[i][7]`. I also am trying to concatenate `myList[i][1]` separated by a ':' for all those lists with matching `myList[i][0]` and `myList[i][7]` and with sums of `myList[i][3]` + `myList[i][4]` and `myList[i][5]` + `myList[i][6]` that match. So essentially for this case only those lists in `myList` with sums of `myList[i][3]` + `myList[i][4]` and `myList[i][5]` + `myList[i][6]` are different from the other lists are then listed in newList. The above newList illustrates these results I am trying to achieve. If anyone has any ideas how to do this they would be greatly appreciated. Thank you!

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