fread

可以将文章内容翻译成中文,广告屏蔽插件可能会导致该功能失效(如失效，请关闭广告屏蔽插件后再试): 问题: I have a large file (3.5G) that I'm trying to import using data.table::fread . It was originally created from an rpt file that was opened as text and saved as a CSV. This has worked fine with smaller files (of the same type of data-same columns and all. This one is just for a longer timeframe and wider reach). When I try and run mydata <- fread("mycsv.csv") I get the error: Error in fread("mycsv.csv") : embedded nul in string: 'y\0e\0a\0r\0' What does this mean? 回答1: We can remove the null terminators on the command line using something like

可以将文章内容翻译成中文,广告屏蔽插件可能会导致该功能失效(如失效，请关闭广告屏蔽插件后再试): 问题: I have practically no knowledge of Matlab, and need to translate some parsing routines into Python. They are for large files, that are themselves divided into 'blocks', and I'm having difficulty right from the off with the checksum at the top of the file. What exactly is going on here in Matlab? status = fseek(fid, 0, 'cof'); fposition = ftell(fid); disp(' '); disp(['** Block ',num2str(iBlock),' File Position = ',int2str(fposition)]); % ----------------- Block Start ------------------ % [A, count] = fread(fid, 3, 'uint32'); if(count == 3)

可以将文章内容翻译成中文,广告屏蔽插件可能会导致该功能失效(如失效，请关闭广告屏蔽插件后再试): 问题: I have no experience when dealing with large files so I am not sure what to do about this. I have attempted to read several large files using file_get_contents ; the task is to clean and munge them using preg_replace() . My code runs fine on small files ; however, the large files (40 MB) trigger an Memory exhausted error: PHP Fatal error: Allowed memory size of 16777216 bytes exhausted (tried to allocate 41390283 bytes) I was thinking of using fread() instead but I am not sure that'll work either. Is there a workaround for this problem?

可以将文章内容翻译成中文,广告屏蔽插件可能会导致该功能失效(如失效，请关闭广告屏蔽插件后再试): 由 翻译 强力驱动 问题: I have a binary file from the MNIST image database, renamed as "myfile.dat". This consists of a set of 4 unsigned 32-bit integers, followed by a chain of unsigned 8-bit integers. I want to read this file and store its contents as an array. Here is my code: file_id = fopen ( 'myfile.dat' , 'rb' ); data = fread ( file_id , 'int' ); size ( data ) class ( data ) And the output is: ans = 2502 1 ans = double The size of (2502, 1) is as expected. But why is it telling me that the data is double , when I have specified it to be int ? I

可以将文章内容翻译成中文,广告屏蔽插件可能会导致该功能失效(如失效，请关闭广告屏蔽插件后再试): 问题: My knowledge of matlab is merely on a need to know basis, so this is probably an elementary question. Nevertheless here it comes: I have got a file containing data (16-bit integers) stored in binary format. How do I read it into a vector /an array in matlab? How do I write this data to a file in matlab? Is there any smart tweak to increase the performance speed when reading/writing a huge amount of data (gigabytes)? 回答1: As Bill the Lizard wrote you can use fread to load the data into a vector. I just want to expand a little on his answer.

Hi in my project I've to read a .bin file which has sensor data in the form of short(16 bit values) . I'm doing this using fread function into a buffer, but I feel that the reading-in is not happening correctly. I mean there is no consistence between what I write and what I read in. Can you guys suggest what is going wrong here? This is not my code from my project... I'm only trying to verify the fread and fwrite functions here. #include<stdio.h> void main() { FILE *fp = NULL; short x[10] = {1,2,3,4,5,6,5000,6,-10,11}; short result[10]; fp=fopen("c:\\temp.bin", "wb"); if(fp != NULL) { fwrite(x

可以将文章内容翻译成中文,广告屏蔽插件可能会导致该功能失效(如失效，请关闭广告屏蔽插件后再试): 由 翻译 强力驱动 问题: Say I have the first test.csv that looks like this , a , b , c , d , e If I try to read it using read.csv , it works fine. read . csv ( "test.csv" , header = FALSE ) # V1 V2 V3 V4 V5 V6 #1 NA a b c d e #Warning message: #In read.table(file = file, header = header, sep = sep, quote = quote, : # incomplete final line found by readTableHeader on 'test.csv' However, if I attempt to read this file using fread , i get an error instead. require ( data . table ) fread ( "test.csv" , header = FALSE ) #Error in fread("test.csv", header =

可以将文章内容翻译成中文,广告屏蔽插件可能会导致该功能失效(如失效，请关闭广告屏蔽插件后再试): 问题: I am using the following code to read a file with the data.table library: fread(myfile, header=FALSE, sep=",", skip=100, colClasses=c("character","numeric","NULL","numeric")) but I get the following error: The supplied 'sep' was not found on line 80. To read the file as a single character column set sep='\n'. It says it did not find sep on line 80, however I set skip=100 so it should not pay attention to the first 100 lines. UPDATE: I tried with skip=101 and it worked but it skips the first line where the data starts I am using version 1.9.2

可以将文章内容翻译成中文,广告屏蔽插件可能会导致该功能失效(如失效，请关闭广告屏蔽插件后再试): 问题: When reading the text below, fread() fails to detect the missing values in columns 8 and 9. This is only with the default option integer64="integer64" . Setting integer64="double" or "character" correctly detects NA s. Note that the file has three types of possible NAs in V8 and V9-- ,, ; , , ; and NA . Appending na.strings=c("NA","N/A",""," "), sep="," as options has no effect. Using read.csv() works the same way as fread(integer="double") . Text to be read (also available as a file integer64_and_NA.csv ): 2012,276,,0,"S1","001",1,

可以将文章内容翻译成中文,广告屏蔽插件可能会导致该功能失效(如失效，请关闭广告屏蔽插件后再试): 问题: I have to work with a collection of 120 files of ~2 GB (525600 lines x 302 columns). The goal is to make some statistics and put the results in a clean SQLite database. Everything works fine when my script import with read.table(), but it's slow. So I've tried with fread, from the data.table package (version 1.9.2), but it give me this error : Error in fread(txt, header = T, select = c("YYY", "MM", "DD", : Not positioned correctly after testing format of header row. ch=' ' The first 2 lines and 7 rows of my data look like that : YYYY MM DD