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  • More elegant way to initialize list of duplicated items in Python

    - by Claudiu
    If I want a list initialized to 5 zeroes, that's very nice and easy: [0] * 5 However if I change my code to put a more complicated data structure, like a list of zeroes: [[0]] * 5 will not work as intended, since it'll be 10 copies of the same list. I have to do: [[0] for i in xrange(5)] that feels bulky and uses a variable so sometimes I even do: [[0] for _ in " "] But then if i want a list of lists of zeros it gets uglier: [[[0] for _ in " "] for _ in " "] all this instead of what I want to do: [[[0]]*5]*5 Has anyone found an elegant way to deal with this "problem"?

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  • Excel VBA: select every other cell in a row range to be copied and pasted vertically

    - by terry alexander
    i have a 2200+ page text file. It is delivered from a customer through a data exchange to us with astericks to separate values and tildes (~) to denote the end of a row. The file is sent to me as a text file in Word. Most rows are split in two (1 row covers a full line and part of a second line). i transfer segments (10 page chunks) of it at a time into Excel where, unfortunately, any zeroes that occur at the end of a row get discarded in the "text to columns" procedure. So, i eyeball every "long" row to insure that zeroes were not lost and manually re-enter any that were. Here is a small bit of sample data: SDQ EA 92 1551 378 1601 151 1603 157 1604 83 The "SDQ, EA, and 92" are irrelevant (artifacts of data transmission). i want to use Excel VBA to select 1551, 1601, 1603, and 1604 (these are store numbers) so that i can copy those values and transpose paste them vertically. i will then go back and copy 378, 151, 157, and 83 (sales values) so that i can transpose paste them next to the store numbers. The next two rows of data contain the same store numbers but give the corresponding dollar values. i will only need to copy the dollar values so they can be transpose pasted vertically next to unit values (e.g. 378, 151, 157, and 83). Just being able to put my cursor on the first cell of interest in the row and run a macro to copy every other cell would speed up my work tremendously. i have tried using activecell and offset references to select a range to copy but have not been successful. Does any have any suggestions for me? Thanks in advance for the help.

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  • How to verify TRIM/discard on encrypted swap?

    - by svarni
    I am using an encrypted swap partition via ecryptfs-setup-swap on my Ubuntu 13.04 computer using a SSD. I have manually set up trim for my ext4 root partition (simply by adding the "discard" option in /etc/fstab). I also manually ran fstrim on the root partition prior to booting and using dstat I saw that for a few seconds several GB/s of data have been written to the disk. That was presumably the effect of the trim command. These high writerates are reproducable by deleting huge files and have not occured before setting up trim, so I take them as evidence for working trim/discard. Manually enabling trim on my root partition has stopped the wearout of my precious new disk from 365 used reserved blocks (out of 6176 total) within three months down to 0 additional used reserved blocks within three additional months (data from SMART attributes). Because I want to minimize the wearout of my SSD I now would like to know whether my swap partition (which is encrypted using ecryptfs-setup-swap) also makes use of the trim/discard option. I tried sudo swapon -d -v /dev/mapper/cryptswap1 but did not receive particular information ("-v") about whether trim/discard ("-d") was applied. If unsupported, i would expect a message. Then I tried sudo dd if=/dev/sda6 count=1 BS=1M | xxd | less directly after booting and when no swapspace was used but I saw not only zeroes. I assume, when looking at freshly trimmed regions, the disk would send zeroes instead of reading random sectors (and according to some forums, (unencrypted) swap space is trimmed once upon boot). Long story short: Are there any ideas on how to test if trim is effectively used for my encrypted swap? And if not, any ideas on how to - at least manually, for once - trim the whole swap space? I wouldn't want to tinker with the partition itself, because I dont know if it needs to be reinitialized as (encrypted) swap - I dont want to be left with an unbootable system :)

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  • Codechef practice question help needed - find trailing zeros in a factorial

    - by manugupt1
    I have been working on this for 24 hours now, trying to optimize it. The question is how to find the number of trailing zeroes in factorial of a number in range of 10000000 and 10 million test cases in about 8 secs. The code is as follows: #include<iostream> using namespace std; int count5(int a){ int b=0; for(int i=a;i>0;i=i/5){ if(i%15625==0){ b=b+6; i=i/15625; } if(i%3125==0){ b=b+5; i=i/3125; } if(i%625==0){ b=b+4; i=i/625; } if(i%125==0){ b=b+3; i=i/125; } if(i%25==0){ b=b+2; i=i/25; } if(i%5==0){ b++; } else break; } return b; } int main(){ int l; int n=0; cin>>l; //no of test cases taken as input int *T = new int[l]; for(int i=0;i<l;i++) cin>>T[i]; //nos taken as input for the same no of test cases for(int i=0;i<l;i++){ n=0; for(int j=5;j<=T[i];j=j+5){ n+=count5(j); //no of trailing zeroes calculted } cout<<n<<endl; //no for each trialing zero printed } delete []T; } Please help me by suggesting a new approach, or suggesting some modifications to this one.

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  • Overwriting lines in file in C

    - by KáGé
    Hi, I'm doing a project on filesystems on a university operating systems course, my C program should simulate a simple filesystem in a human-readable file, so the file should be based on lines, a line will be a "sector". I've learned, that lines must be of the same length to be overwritten, so I'll pad them with ascii zeroes till the end of the line and leave a certain amount of lines of ascii zeroes that can be filled later. Now I'm making a test program to see if it works like I want it to, but it doesnt. The critical part of my code: file = fopen("irasproba_tesztfajl.txt", "r+"); //it is previously loaded with 10 copies of the line I'll print later in reverse order /* this finds the 3rd line */ int count = 0; //how much have we gone yet? char c; while(count != 2) { if((c = fgetc(file)) == '\n') count++; } fflush(file); fprintf(file, "- . , M N B V C X Y Í U Á É L K J H G F D S A Ú O P O I U Z T R E W Q Ó Ü Ö 9 8 7 6 5 4 3 2 1 0\n"); fflush(file); fclose(file); Now it does nothing, the file stays the same. What could be the problem? Thank you.

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  • How much is modern programming still tied to underyling digital logic?

    - by New Talk
    First of all: I've got no academic background. I'm working primarily with Java and Spring and I'm also fond of web programming and relational databases. I hope I'm using the right terms and I hope that this vague question makes some sense. Today the following question came to my mind: How much is modern programming still tied to the underlying digital logic? With modern programming I mean concepts like OOP, AOP, Java 7, AJAX, … I hope you get the idea. Do they no longer need the digital logic with which computers are working internally? Or is binary logic still ubiquitous when programming this way? If I'd change the inner workings of a computer overnight, would it matter, because my programming techniques are already that abstract? P. S.: With digital logic I mean the physical representation of everything "inside" the computer as zeroes and ones. Changed "binary" to "digital".

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  • Essbase Data precision unraveled

    - by THE
    (guest reference added by Nancy) Anyone who has been working with Data import and exoport as well as the Essbase Excel Add In has probably come across a phenomenon that is called data precision: Lots of zeroes are added to any given number that has been calculated by Essbase, and this gets displayed as "10.0000000000001" or "9.99999999999999" instead of a simple "10" . This question is one of the recurring ones that Support get asked over and over again, and we therefore feel the need to give an explanation to it: I would like to point you to the note The Limits of Data Precision in Essbase (Doc ID 1311188.1) which explains in detail why these numbers are showing up and what to do about it.

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  • adding zeros in objective-c string formats

    - by Chris
    Hello- Quick question: I am trying to fill in empty spaces with a specific number of zeroes in an NSString stringWithFormat formatting string. For example, I want: @"The number is %d", 5 // I want this to output 'the number is 05' @"the number is %d", 10 // I want this to output 'the number is 10' I know how to do this in Java, but I cant seem to find the same function in objective-c. Any help would be great.

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  • C socket programming: connect() hangs

    - by Fantastic Fourier
    Hey all, I'm about to rip my hair out. I have this client that tries to connect to a server, everything seems to be fine, using gethostbyname(), socket(), bind(), but when trying toconnect()` it just hangs there and the server doesn't see anything from the client. I know that the server works because another client (also in C) can connect just fine. What causes the server to not see this incoming connection? I'm at the end of my wits here. The two different clients are pretty similar too so I'm even more lost. if (argc == 2) { host = argv[1]; // server address } else { printf("plz read the manual\n"); exit(1); } hserver = gethostbyname(host); if (hserver) { printf("host found: %p\n", hserver); printf("host found: %s\n", hserver->h_name ); } else { printf("host not found\n"); exit(1); } bzero((char * ) &server_address, sizeof(server_address)); // copy zeroes into string server_address.sin_family = AF_INET; server_address.sin_addr.s_addr = htonl(hserver->h_addr); server_address.sin_port = htons(SERVER_PORT); bzero((char * ) &client_address, sizeof(client_address)); // copy zeroes into string client_address.sin_family = AF_INET; client_address.sin_addr.s_addr = htonl(INADDR_ANY); client_address.sin_port = htons(SERVER_PORT); sockfd = socket(AF_INET, SOCK_STREAM, 0); if (sockfd < 0) exit(1); else { printf("socket is opened: %i \n", sockfd); info.sock_fd = sockfd; rv = fcntl(sockfd, F_SETFL, O_NONBLOCK); // socket set to NONBLOCK if(rv < 0) printf("nonblock failed: %i %s\n", errno, strerror(errno)); else printf("socket is set nonblock\n"); } timeout.tv_sec = 0; // seconds timeout.tv_usec = 500000; // micro seconds ( 0.5 seconds) setsockopt(sockfd, SOL_SOCKET, SO_RCVTIMEO, &timeout, sizeof(struct timeval)); rv = bind(sockfd, (struct sockaddr *) &client_address, sizeof(client_address)); if (rv < 0) { printf("MAIN: ERROR bind() %i: %s\n", errno, strerror(errno)); exit(1); } else printf("socket is bound\n"); rv = connect(sockfd, (struct sockaddr *) &server_address, sizeof(server_address)); printf("rv = %i\n", rv); if (rv < 0) { printf("MAIN: ERROR connect() %i: %s\n", errno, strerror(errno)); exit(1); } else printf("connected\n"); Any thoughts or insights are deeply greatly humongously appreciated. -Fourier

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  • Python string formatting too slow

    - by wich
    I use the following code to log a map, it is fast when it only contains zeroes, but as soon as there is actual data in the map it becomes unbearably slow... Is there any way to do this faster? log_file = open('testfile', 'w') for i, x in ((i, start + i * interval) for i in range(length)): log_file.write('%-5d %8.3f %13g %13g %13g %13g %13g %13g\n' % (i, x, map[0][i], map[1][i], map[2][i], map[3][i], map[4][i], map[5][i]))

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  • Given an array of integers [x0 x1 x2], how do you calculate all possible permutations from [0 0 0] t

    - by user319951
    I am writing a program that takes in an ArrayList and I need to calculate all possible permutations starting with a list of zeroes, up to the value in the corresponding input list. Does anyone know how to iteratively calculate these values? For example, given [ 1 2 ] as input, it should find and store the following lists: [0 0], [1 0], [1 1], [1 2], [0 1], [0 2] Thanks!

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  • logic question about factorials

    - by Syom
    I have a problem and can't solve it alone. My teacher gives me one logic task today, and i'm sure you can help me. How can I count the number of zeroes at the end of factorial(41). (on paper) I understand that it has nothing to do with programing, but I'm sure programers can help me. Thanks in advance.

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  • Adding zeros when length is less

    - by David
    Is there a smart way to convert numbers to string and automatically add zeroes so the length is the same as the maximum? like this: for (var i=0; i<30; i++) { var c = i.toString(); if (c.length == 1) { c = '0'+=c; } } But smarter

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  • How do I get numbers before and after a colon within a cell in Calc?

    - by Dave M G
    I have some cells which contain times entered in by users, which are written in the following format: mm:ss. There are never any hours. The seconds always have leading zeroes. The minutes may or may not have leading zeros. Because I need to separate out the minutes and seconds for various operations, I need to be able to get at the numbers before and after the colon. How do I select the number before a colon in a cell, and how do I select the number after?

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  • Fill rows down quickly (column or matrix of zeros)

    - by Mark Miller
    I have an extremely basic question, but I have never found the answer by searching the internet. I simply want to create a large column of zeros with Excel. Sometimes I want to create a huge matrix of zeros (maybe 600 rows by 500 columns) and then replace a few zeros with 1's to create a model design matrix. I have always started by creating a column of, for example, 10 zeros, copying and pasting those zeroes, then copying and pasting the resulting column of 20 zeros, etc., until I had the desired number of rows. Then I would copy and paste that column of zeros one at a time over and over until I had the desired number of columns. This procedure is tedious and time-consuming and I know there must be an easier way. Do you know of any other methods?

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  • Zipcodes in CSV Generation

    - by BRADINO
    When exporting to CSV format, then opening in a spreadsheet program like Excel zipcodes that start with a zero or zeroes have the preceding zeros stripped off. Obviously it is because the spreadsheet sees that column as integers and preceding zeros in integers are useless. A quick and dirty trick to force Excel (hopefully you are using OpenOffice) to display the full zipcode, we wrap it in double quotes and put an equal sign in front of it, to force it to be a string like this: $zipcode = 00123; $data = '="' . $zipcode . '"' ; So if you are doing the straight query to CSV export, using the fputcsv function it would look something like this. Basically just overwrite the value in the row and then continue along. while ($row = mysql_fetch_assoc($query)){         $row['zipcode'] = '="'.$row['zipcode'].'"';     fputcsv($output, $row); } php csv zipcode csv number csv force string

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  • SQL SERVER – Removing Leading Zeros From Column in Table

    - by pinaldave
    Some questions surprises me and make me write code which I have never explored before. Today was similar experience as well. I have always received the question regarding how to reserve leading zeroes in SQL Server while displaying them on the SSMS or another application. I have written articles on this subject over here. SQL SERVER – Pad Ride Side of Number with 0 – Fixed Width Number Display SQL SERVER – UDF – Pad Ride Side of Number with 0 – Fixed Width Number Display SQL SERVER – Preserve Leading Zero While Coping to Excel from SSMS Today I received a very different question where the user wanted to remove leading zero and white space. I am using the same sample sent by user in this example. USE tempdb GO -- Create sample table CREATE TABLE Table1 (Col1 VARCHAR(100)) INSERT INTO Table1 (Col1) SELECT '0001' UNION ALL SELECT '000100' UNION ALL SELECT '100100' UNION ALL SELECT '000 0001' UNION ALL SELECT '00.001' UNION ALL SELECT '01.001' GO -- Original data SELECT * FROM Table1 GO -- Remove leading zeros SELECT SUBSTRING(Col1, PATINDEX('%[^0 ]%', Col1 + ' '), LEN(Col1)) FROM Table1 GO -- Clean up DROP TABLE Table1 GO Here is the resultset of above script. It will remove any leading zero or space and will display the number accordingly. This problem is a very generic problem and I am confident there are alternate solutions to this problem as well. If you have an alternate solution or can suggest a sample data which does not satisfy the SUBSTRING solution proposed, I will be glad to include them in follow up blog post with due credit. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: PostADay, SQL, SQL Authority, SQL Function, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology

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  • Troubleshooting wireless network connectivity

    - by taserian
    I'm currently running Ubuntu 10.10, and I'm running into trouble keeping my wireless connection alive. After rebooting, I get about 5-10 minutes of a good speed connection; afterwards, the connection just zeroes out. I've gotten around to stirring up a shell script that gives me another 10 minutes or so of connectivity. Script contents below: #! /bin/bash sudo ifconfig wlan0 up echo "Enabling wireless device . . ." sleep 5 sudo iwconfig wlan0 essid MyNetworkName echo "Connecting to network. . ." sleep 10 sudo dhclient wlan0 echo "Getting IP address. . ." sleep 5 echo "Done. Closing window. . ." sleep 5 Shortly after running the line "sudo iwconfig wlan0 essid MyNetworkName" from the script, I notice the speed pick up. Other computers in my home running Windows XP are not affected by this problem, so all indications point to my Ubuntu machine. Does anyone have any pointers as to how to resolve this?

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  • Automatic TRIM vs. manual TRIM

    - by Eike Cochu
    I am currently trying to find out how to trim with my new TP and was wondering about the difference of manual/online trimming. Here is my setup: ThinkPad T430s with SSD Samsung 830, 128GB and Xubuntu 12.10, here are some outputs to check if trim will work on my system (got these from here: http://wiki.ubuntuusers.de/SSD/TRIM) root@eike-tp:~# sudo hdparm -I /dev/sda | grep -i TRIM * Data Set Management TRIM supported (limit 8 blocks) First, I tried the online trimming: How to enable TRIM? my fstab with discard inserted: UUID=d6c49c17-a4f1-466c-9f7e-896c20db3bba / ext4 discard,noatime,errors=remount-ro 0 1 # swap was on /dev/sda5 during installation UUID=a0322f5f-c6c1-4896-863f-668f0638d8cf none swap sw 0 0 tmpfs /tmp tmpfs defaults,noatime,mode=1777 0 0 I tried to test if it works (but I don't get any zeroes when I try it with /dev/sda), but found out that this method is only possible with SSD type 2 and I seem to have type 3. So I don't know if it works or not. The Ubuntuwiki (first link) recommends manual trimming, so I set up a daily cronjob instead of discard: #!/bin/sh LOG=/var/log/batched_discard.log echo "*** $(date -R) ***" >> $LOG fstrim -v / >> $LOG the wiki article suggests weekly or daily. Now to my questions: How often executes the automated trim? How often is recommended? Online vs. manual trimming? Thank you for your help

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  • What is the recommended way to empty a SSD?

    - by Lekensteyn
    I've just received my new SSD since the old one died. This Intel 320 SSD supports TRIM. For testing purposes, my dealer put malware, err, Windows on it. I want to get rid of it and install Kubuntu on it. It does not have to be a "secure wipe", I just need the empty the disk in the mosy healthy way. I believe that dd if=/dev/zero of=/dev/sda just fills the blocks with zeroes and thereby taking another write (correct me if I'm wrong). I've seen the answer How to enable TRIM, but it looks like it's suited for clearing empty blocks, not wiping the disk. hdparm seems to be the program to do it, but I'm not sure if it clears the disk OR cleans empty blocks. From its manual page: --trim-sector-ranges For Solid State Drives (SSDs). EXCEPTIONALLY DANGEROUS. DO NOT USE THIS OPTION!! Tells the drive firmware to discard unneeded data sectors, destroying any data that may have been present within them. This makes those sectors available for immediate use by the firmware's garbage collection mechanism, to improve scheduling for wear-leveling of the flash media. This option expects one or more sector range pairs immediately after the option: an LBA starting address, a colon, and a sector count, with no intervening spaces. EXCEPTIONALLY DANGEROUS. DO NOT USE THIS OPTION!! E.g. hdparm --trim-sector-ranges 1000:4 7894:16 /dev/sdz How can I make all blocks appear as empty using TRIM?

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  • How should I compress a file with multiple bytes that are the same with Huffman coding?

    - by Omega
    On my great quest for compressing/decompressing files with a Java implementation of Huffman coding (http://en.wikipedia.org/wiki/Huffman_coding) for a school assignment, I am now at the point of building a list of prefix codes. Such codes are used when decompressing a file. Basically, the code is made of zeroes and ones, that are used to follow a path in a Huffman tree (left or right) for, ultimately, finding a byte. In this Wikipedia image, to reach the character m the prefix code would be 0111 The idea is that when you compress the file, you will basically convert all the bytes of the file into prefix codes instead (they tend to be smaller than 8 bits, so there's some gain). So every time the character m appears in a file (which in binary is actually 1101101), it will be replaced by 0111 (if we used the tree above). Therefore, 1101101110110111011011101101 becomes 0111011101110111 in the compressed file. I'm okay with that. But what if the following happens: In the file to be compressed there exists only one unique byte, say 1101101. There are 1000 of such byte. Technically, the prefix code of such byte would be... none, because there is no path to follow, right? I mean, there is only one unique byte anyway, so the tree has just one node. Therefore, if the prefix code is none, I would not be able to write the prefix code in the compressed file, because, well, there is nothing to write. Which brings this problem: how would I compress/decompress such file if it is impossible to write a prefix code when compressing? (using Huffman coding, due to the school assignment's rules) This tutorial seems to explain a bit better about prefix codes: http://www.cprogramming.com/tutorial/computersciencetheory/huffman.html but doesn't seem to address this issue either.

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  • Rewriting An URL With Regular Expression Substitution in Routes

    - by Sean M
    In my Pylons app, some content is located at URLs that look like http://mysite/data/31415. Users can go to that URL directly, or search for "31415" via the search page. My constraints, however, mean that http://mysite/data/000031415 should go to the same page as the above, as should searches for "0000000000031415." Can I strip leading zeroes from that string in Routes itself, or do I need to do that substitution in the controller file? If it's possible to do it in routing.py, I'd rather do it there - but I can't quite figure it out from the documentation that I'm reading.

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  • Printing entire array in C#

    - by DMan
    I have a simple 2D array: int[,] m = {{0,0,0,0,0,0,0,0,0,0}, {0,0,0,0,0,0,0,0,0,0} }; How can I print this out onto a text file or something? I want to print the entire array onto a file, not just the contents. For example, I don't want a bunch of zeroes all in a row: I want to see the {{0,0,0,0,0,0,0,0,0,0}, {0,0,0,0,0,0,0,0,0,0} }; in it.

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