Read a file with textscan.

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Allen Hammack
Allen Hammack on 25 Mar 2022
Commented: Stephen23 on 28 Mar 2022
I have a text file that I'm trying to read with textscan. The top of my file looks like
######################################################################
Test File Name: MNTFEPLANC-122-202203171547
Timestamp: 202203171547
Test Type: FILL Valve Selction: BOTH Valve Cycle Time: 2
######################################################################
20220317154734, 0.0, 0.0, 0.0, 0.0,17714,17449,20464,17041,17028, 0.000000,0.000000,0.000000
20220317154734, 0.0, 0.0, 0.0, 0.0,17714,17449,20464,17041,17028, 0.000000,0.000000,0.000000
20220317154734, 0.0, 0.0, 0.0, 0.0,17714,17449,20464,17041,17028, 0.000000,0.000000,0.000000
20220317154734, 0.0, 0.0, 0.0, 0.0,17714,17449,20464,17041,17028, 0.000000,0.000000,0.000000
20220317154734, 0.0, 0.0, 0.0, 0.0,17714,17449,20464,17041,17028, 0.000000,0.000000,0.000000
20220317154734, 0.0, 0.0, 0.0, 0.0,17714,17449,20464,17041,17028, 0.000000,0.000000,0.000000
20220317154734, 0.0, 0.0, 0.0, 0.0,17714,17449,20464,17041,17028, 0.000000,0.000000,0.000000
20220317154734, 0.0, 0.0, 0.0, 0.0,17714,17449,20464,17041,17028, 0.000000,0.000000,0.000000
I open the file using
raw_data_file = fopen(file_name,'rt') % The full path of "file_name" has been ommitted for brevity.
which yields
raw_data_file =
17
I read the file using
fe_data_read = textscan(raw_data_file,'%f%f%f%f%f%f%f%f%f%f%f%f%f','Delimiter',',');
which yields
fe_data_read =
1×13 cell array
Columns 1 through 10
{0×1 double} {0×1 double} {0×1 double} {0×1 double} {0×1 double} {0×1 double} {0×1 double} {0×1 double} {0×1 double} {0×1 double}
Columns 11 through 13
{0×1 double} {0×1 double} {0×1 double}
I tried to create a variable with values being the first column using
test_date_time = fe_data_read{1}
which yields
test_date_time =
0×1 empty double column vector
Why is "test_date_time" not being populated with the values in the first column of my text file? What am I doing wrong?

Answers (2)

Jan
Jan on 25 Mar 2022
Edited: Jan on 25 Mar 2022
The file starts with this line:
######################################################################
This does not match the format string '%f%f%f%f%f%f%f%f%f%f%f%f%f' or the Delimiter=',' in any way. Therefore textscan replies an empty output.
You have to tell textscan, that the first 6 lines are a header and have to be skipped. Use the 'Headerlines" argument.
By the wya, do you have a reason to open the file in the slower text mode?
  5 Comments
Stephen23
Stephen23 on 28 Mar 2022
That file has a mix of newline characters, but Walter Roberson's code imports it without any problems:
fnm = 'orig_data_trim.txt';
opt = detectImportOptions(fnm, 'HeaderLines', 6);
opt = setvartype(opt, 1, 'datetime');
opt = setvaropts(opt, 1, 'InputFormat', 'uuuuMMddHHmmss');
T = readtable(fnm, opt)
T = 29×13 table
Var1 Var2 Var3 Var4 Var5 Var6 Var7 Var8 Var9 Var10 Var11 Var12 Var13 ______________ ____ ____ ____ ____ _____ _____ _____ _____ _____ _____ _____ _____ 20220317154734 0 0 0 0 17714 17449 20464 17041 17028 0 0 0 20220317154734 0 0 0 0 17714 17449 20464 17041 17028 0 0 0 20220317154734 0 0 0 0 17714 17449 20464 17041 17028 0 0 0 20220317154734 0 0 0 0 17714 17449 20464 17041 17028 0 0 0 20220317154734 0 0 0 0 17714 17449 20464 17041 17028 0 0 0 20220317154734 0 0 0 0 17714 17449 20464 17041 17028 0 0 0 20220317154734 0 0 0 0 17714 17449 20464 17041 17028 0 0 0 20220317154734 0 0 0 0 17714 17449 20464 17041 17028 0 0 0 20220317154734 0 0 0 0 17714 17449 20464 17041 17028 0 0 0 20220317154734 0 0 0 0 17714 17449 20464 17041 17028 0 0 0 20220317154734 0 0 0 0 17713 17450 20463 17042 17028 0 0 0 20220317154734 0 0 0 0 17712 17450 20462 17043 17028 0 0 0 20220317154734 0 0 0 0 17712 17450 20462 17043 17028 0 0 0 20220317154734 0 0 0 0 17712 17450 20462 17043 17028 0 0 0 20220317154734 0 0 0 0 17712 17450 20462 17043 17028 0 0 0 20220317154734 0 0 0 0 17712 17450 20462 17043 17028 0 0 0

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Stephen23
Stephen23 on 25 Mar 2022
opt = {'Delimiter',',','Headerlines',6,'CollectOutput',true};
fmt = ['%{uuuuMMddHHmmss}D',repmat('%f',1,12)];
fid = fopen('new.txt','rt');
tmp = textscan(fid,fmt,opt{:});
fclose(fid);
tmp{1}
ans = 8×1 datetime array
20220317154734 20220317154734 20220317154734 20220317154734 20220317154734 20220317154734 20220317154734 20220317154734
tmp{2}
ans = 8×12
0 0 0 0 17714 17449 20464 17041 17028 0 0 0 0 0 0 0 17714 17449 20464 17041 17028 0 0 0 0 0 0 0 17714 17449 20464 17041 17028 0 0 0 0 0 0 0 17714 17449 20464 17041 17028 0 0 0 0 0 0 0 17714 17449 20464 17041 17028 0 0 0 0 0 0 0 17714 17449 20464 17041 17028 0 0 0 0 0 0 0 17714 17449 20464 17041 17028 0 0 0 0 0 0 0 17714 17449 20464 17041 17028 0 0 0
  1 Comment
Walter Roberson
Walter Roberson on 26 Mar 2022
filename = 'https://www.mathworks.com/matlabcentral/answers/uploaded_files/941499/new.txt';
opt = detectImportOptions(filename, 'HeaderLines', 6);
opt = setvartype(opt, 1, 'datetime');
opt = setvaropts(opt, 1, 'InputFormat', 'uuuuMMddHHmmss');
T = readtable(filename, opt)
T = 8×13 table
Var1 Var2 Var3 Var4 Var5 Var6 Var7 Var8 Var9 Var10 Var11 Var12 Var13 ______________ ____ ____ ____ ____ _____ _____ _____ _____ _____ _____ _____ _____ 20220317154734 0 0 0 0 17714 17449 20464 17041 17028 0 0 0 20220317154734 0 0 0 0 17714 17449 20464 17041 17028 0 0 0 20220317154734 0 0 0 0 17714 17449 20464 17041 17028 0 0 0 20220317154734 0 0 0 0 17714 17449 20464 17041 17028 0 0 0 20220317154734 0 0 0 0 17714 17449 20464 17041 17028 0 0 0 20220317154734 0 0 0 0 17714 17449 20464 17041 17028 0 0 0 20220317154734 0 0 0 0 17714 17449 20464 17041 17028 0 0 0 20220317154734 0 0 0 0 17714 17449 20464 17041 17028 0 0 0

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