I'm using the file I/O macros for SV, and I want to print out the number of a parsed line in a file I'm loading and scanning. I couldn't figure out a way to do so. Any help ?
statusF = $fgets(line, input_file);
// Here I would like to print the current line number
statusF = $sscanf(line, "%h\n", a);
Thank you in advance,
If the file you are reading has a fixed line size, like in a hex dumpfile, you can use $ftell to get the character position and divide (or modulo %) by the line size.
Otherwise you will have count the number of times you called $fgets.
Related
I am reading in a binary EDF file and I have to split it into multiple smaller EDF files at specific points and then adjust some of the values inside. Overall it works quite well but when I read in the file it combines 2 character arrays with each other. Obviously everything afterwords gets corrupted as well. I am at a dead end and have no idea what I'm doing wrong.
The part of the code (writing) that has to contain the problem:
byt=fread(fid,8,'*char');
fwrite(tfid,byt,'*char');
fwrite(tfid,fread(fid,44));
%new number of records
s = records;
fwrite(tfid,s,'*char');
fseek(fid,8,0);
%test
fwrite(tfid,fread(fid,8,'*char'),'*char');
When I use the reader it combines the records (fwrite(tfid,s,'*char'))
with the value of the next variable. All variables before this are displayed correctly. The relevant code of the reader:
hdr.bytes = str2double(fread(fid,8,'*char')');
reserved = fread(fid,44);%#ok
hdr.records = str2double(fread(fid,8,'*char')');
if hdr.records == -1
beep
disp('There appears to be a problem with this file; it returns an out-of-spec value of -1 for ''numberOfRecords.''')
disp('Attempting to read the file with ''edfReadUntilDone'' instead....');
[hdr, record] = edfreadUntilDone(fname, varargin);
return
end
hdr.duration = str2double(fread(fid,8,'*char')');
The likely problem is that your character array s does not have 8 characters in it, but you expect there to be 8 when you read it from the file. Whatever the number of characters in the array is, that's how many values fwrite will write out to the file. Anything less than 8 characters and you'll end up reading part of the next piece of data when you read from the file.
One fix would be to pad s with blanks before writing it:
s = [blanks(8-numel(records)) records];
In addition, the syntax '*char' is only valid when using fread: the * indicates that the output class should be 'char' as well. It's unnecessary when using fwrite.
I want to read and write the same file simultaneously. Here is a simplified code:
clc;
close all;
clearvars;
fd = fopen ('abcd.txt','r+'); %opening file abcd.txt given below
while ~feof(fd)
nline = fgetl(fd);
find1 = strfind(nline,'abcd'); %searching for matching string
chk1 = isempty(find1);
if(chk1==0)
write = '0000'; %in this case, matching pattern found
% then replace that line by 0000
fprintf(fd,'%s \n',write);
else
continue;
end
end
File abcd.txt
abcde
abcd23
abcd2
abcd355
abcd65
I want to find text abcd in string of each line and replace the entire line by 0000. However, there is no change in the text file abcd.txt. The program doesn't write anything in the text file.
Someone can say read each line and write a separate text file line by line. However, there is a problem in this approach. In the original problem, instead of finding matching text `abcd, there is array of string with thousands of elements. In that case, I want to read the file, parse the file for find matching string, replace string as per condition, go to next iteration to search next matching string and so on. So in this approach, line by line reading original file and simultaneously writing another file does not work.
Another approach can be reading the entire file in memory, replacing the string and iterate. But I am not very sure how will it work. Another issue is memory usage.
Any comments?
What you are attempting to do is not possible in a efficient way. Replacing abcde with 0000, which should be done for the first line, would require all remaining text forward because you remove one char.
Instead solve this reading one file and write to a second, then remove the original file and rename the new one.
I am using the "textread" function to read a file like this:
[files1,time_in1,time_out1,lable_id1] = textread(ref_file,'%s%f%f%s%*[^\n]','delimiter',' ');
ref_file shows as next:
ACCEDE00000 0 10 sn
ACCEDE00100 0 5 sn
ACCEDE00300 0 10 sn
The console throws the next error:
Error using dataread
Trouble reading floating point number from file (row 3, field 3) ==> sn\n
I don't understand why shows this error. I think that the format is correct: I have a string in the last position of the line (%s) but Matlab read it like a float. Also, in the above lines reads the string correctly.
Can anybody help me? Thank you!!
Change your current format to
[files1,time_in1,time_out1,lable_id1] = textread(ref_file,'%s %f %f %s');
and it's recommended to use textscan, because textread is deprecated. The new code would be something like this
fileID = fopen(ref_file);
C = textscan(fileID,'%s %f %f %s');
files1=C{1};
time_in1=C{2};
time_out1=C{3};
lable_id1=C{4};
The issue is *[^\n], you should not need to add a specifier for newline, and what you're doing is asking it to look for a string that's not \n (five values, not four), so it's probably hopping to the next line and taking the first string, resulting in the second value (number) there being read as a string, and so on, until it tries to read one of the strings as a float.
If you need to, you can use 'endofline' parameter but it should be able to figure out endofline by itself unless you're using something really non-standard.
side note: textread is now non-recommended and you should really use textscan instead.
I have a txt file that looks like this:
1 17.3
2 18.2
3 18.6
I would like to make a variable (for example temp) which would store store first value (17.3). I would then compare this value with something else (< temp 20). Next step would be to store second value in temp (18.2), so I could again compare values.
Any help would be appreciated!
In Matlab it would look like this:
A=importdata(...)
i=0;
while i<length(temp) do
temp=A(i,2)
i=i+1;
if temp < 20
...
end
end
There are several ways to skin this cat in R6RS:
You can use read. read will read any Scheme datum so since these are all numbers read will read the next number.
You can make your own parser. You read one char at a time and when you hit a space or linefeed you take the list of chars you have though list->string to get string and then string->number This can also be done in two parts reading lines then parsing each line or do a slurp first then process the string.
I have a huge csv file that I want to load with matlab. However, I'm only interested in specific columns that I know the name.
As a first step, I would like to just check how many columns the csv file has. How can I do that with matlab?
As Jonesy and erelender suggest, I would think this will do it:
fid=fopen(filename);
tline = fgetl(fid);
fclose(fid);
length(find(tline==','))+1
Since you don't seem to know what kind of carriage return character (or character encoding?) is being used then I would suggest progressively sampling your file until you encounter a recognizable CR character. One way to do this is to loop over something like
A = fscanf(fileID, ['%' num2str(N) 'c'], sizeA);
where N is the number of characters to read. At each iteration test A for presence of carriage return characters, stop if one is encountered. Once you know where the carriage return is just repeat with the right N and perform the length(find...) operation, or alternately accumulate the number of commas at each iteration. You may want to check that your file is being read along rows (is it always?), check a few samples to make sure it is.
1-) Read the first line of file
2-) Count the number of commas, or seperator characters if it is not comma
3-) Add 1 to the count and the result is the number of columns in the file.
If the csv has only numeric value you can use:
M=csvread('file_name.csv');
[row,col]=size(M);