file-manipulation | 易学教程

Adding text to start of each new line in a .txt file

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问题 I would like to add a predefined text to each new line on a text file and create a new text file with the added text. Please help. 回答1: In Windows, this will do it: (for /f "delims=" %L in (oldfile.txt) do @echo predefined text %L)> newfile.txt Note that in a batch file you'll need to use double % signs: (for /f "delims=" %%L in (oldfile.txt) do @echo predefined text %%L)> newfile.txt Note also that if you don't put the ">" right after the %L, you will get a space after every line. If you use

Copy multiple files from multiple folders to a single folder using R

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问题 Hey I want to ask how to copy multiple files from multiple folders to a single folders using R language Assuming there are three folders: desktop/folder_A/task/sub_task/ desktop/folder_B/task/sub_task/ desktop/folder_C/task/sub_task/ In each of the sub_task folder, there are multiple files. I want to copy all the files in the sub_task folders and paste them in a new folder (let's name this new folder as "all_sub_task") on desktop. Can anyone show me how to do it in R using the loop or apply

Limit of file size for truncate in R

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问题 From ?truncate : truncate truncates a file opened for writing at its current position. It works only for file connections, and is not implemented on all platforms: on others (including Windows) it will not work for large (> 2Gb) files. What is the cause of the 2Gb limit on Windows? Does it matter if it's 64bit Windows, or the file system is NTFS? Does the version of Windows matter (XP, 7, 8, 10)? Is there a built-in R function or a function in some R package that achieves the same effect on

Keeping log files under a certain size

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问题 I have an application that is running on a stand-alone panel PC in a kiosk (C#/WPF). It performs some typical logging operations to a text file. The PC has some limited amount of disk space to store these logs as they grow. What I need to do is be able to specify the maximum size that a log file is allowed to be. If, when attempting to write to the log, the max size is exceeded, new data will be written to the end of the log and the oldest data will be purged from the beginning. Getting the

Hashmap single key holding a class. count the key and retrieve counter

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I am working on a database self project. I have an input file got from: http://ir.dcs.gla.ac.uk/resources/test_collections/cran/ After processing into 1400 separate file, each named 00001.txt ,... 01400.txt ...) and after applying Stemming on them, I will store them separately in a specific folder lets call it StemmedFolder with the following format: in StemmedFolder: 00001.txt includes: investig aerodynam wing slipstream brenckman experiment investig aerodynam wing in StemmedFolder: 00756.txt includes: remark eddi viscos compress mix flow lu ting And so on.... I wrote the codes that do: get

Replace nth line in a text file

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问题 How do I go about in replacing the nth line of a text file in R? 回答1: To replace the third line of this: $ cat junk.txt sic transit gloria mundi temeo danoas et dona ferentes Do this: > latin = readLines("junk.txt",-1) > latin[3]="per ardua ad astra" > writeLines(latin,"junkout.txt") and get: $ cat junkout.txt sic transit gloria mundi per ardua ad astra et dona ferentes You can writeLines(latin,"junk.txt") and overwrite the input file if you want. 回答2: I don't know if there is an option to

Keeping log files under a certain size

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I have an application that is running on a stand-alone panel PC in a kiosk (C#/WPF). It performs some typical logging operations to a text file. The PC has some limited amount of disk space to store these logs as they grow. What I need to do is be able to specify the maximum size that a log file is allowed to be. If, when attempting to write to the log, the max size is exceeded, new data will be written to the end of the log and the oldest data will be purged from the beginning. Getting the file size is no problem, but are there any typical file manipulation techniques to keep a file under a

How to use “append” command on specific position in a text file using Visual Basic?

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问题 Text file: test1 test2 test3 test4 I want to write after "test2" - something. I tried first time to open the file and I read the position where is test2. After that I opened the text file in Append format but I don't know how to write on specific position. I must to use next commands or others in Visual Basic: for reading from a text file: Open Test_Filename For Input As # for appending in a text file: Open Test_Filename For Append As #3 Any helps will be great. Edit: LineNum = 1 LineRead = 0

Replace nth line in a text file

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How do I go about in replacing the nth line of a text file in R? To replace the third line of this: $ cat junk.txt sic transit gloria mundi temeo danoas et dona ferentes Do this: > latin = readLines("junk.txt",-1) > latin[3]="per ardua ad astra" > writeLines(latin,"junkout.txt") and get: $ cat junkout.txt sic transit gloria mundi per ardua ad astra et dona ferentes You can writeLines(latin,"junk.txt") and overwrite the input file if you want. Michael I don't know if there is an option to change a specific line in the streaming file (seek in file), although you have the option to read the file

how to delete a file with R? [duplicate]

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问题 This question already has answers here : Closed 6 years ago . Possible Duplicate: Automatically Delete Files/Folders in R I would like to know if there is a way in R to check up if a file is in my current directory, and if it is there then the program deletes it? I know that other languages have direct access to OS functions to do this task, but I am a little bit dubious if R has that capability. 回答1: How about: #Define the file name that will be deleted fn <- "foo.txt" #Check its existence