reading a text file by correct date format
1 view (last 30 days)
Show older comments
Hi,
I have a text file like below. How can I read the 2nd column/format to read it using MATLAB. I am having a difficulty is reading it using the correct format for yyyy/mm/dd hh:mm. Any help is appreciated.
Thanks in advance.
filePattern = fullfile(myFolder, '*.txt');
csvFiles = dir(filePattern);
fmt='%d %4d/%2d/%2d %4d %*[^\n]';
for i=1:length(csvFiles)
fid = fopen(fullfile(myFolder,csvFiles(i).name));
c=cell2mat(textscan(fid,fmt,'headerlines',18,'collectoutput',1,'delimiter','\t'));
fid=fclose(fid);
end
![](https://www.mathworks.com/matlabcentral/answers/uploaded_files/152974/image.bmp)
4 Comments
dpb
on 1 Jan 2016
Again, we can't test your file unless you attach a section of it but as I said earlier, forget setting the 'delimiter' field entirely; let it default. Failing that, again, give us the actual data, not a picture of it.
Accepted Answer
dpb
on 2 Jan 2016
OK, as I suspected, the file format is NOT tab delimited but fixed-width columns except the records aren't the same length; the record is terminated after the last data in the record. So, the lines are as follows:
'010802 2015/01/01 00:00 AR'
'010802 2015/01/01 00:15 AR'
...
'010802 2015/04/20 00:00 15.20 '
'010802 2015/04/20 00:15 15.20 '
...
where I've enclosed the two record types in single quotes to be able to see what's actually in the file. Since C (and hence Matlab) formatted input ignores whitespace excepting if you read counted characters (as in '%Nc'), you can't write a single format string to parse both data records at the same time for the whole file.
It is possible, however, to read a record at a time with the same format string w/ textscan as it will pick up after the error of the failed conversion for an empty field--I created a very short version of your file without the preamble other than the header line and a few of each record type for demonstration purposes:
>> fmt=['%d %4d/%2d/%2d %2d:%2d %f%*[^\n]'];
>> fid=fopen('test.txt');
>> fgetl(fid); % throw away the header line
>> while ~feof(fid) % read record at a time, echo to terminal
textscan(fid,fmt,1,'headerlines',1)
end
ans =
[10802] [2015] [4] [19] [22] [45] [0x1 double]
ans =
[10802] [2015] [4] [19] [23] [0] [0x1 double]
ans =
[10802] [2015] [4] [19] [23] [15] [0x1 double]
...
[10802] [2015] [4] [20] [0] [0] [15.2000]
ans =
[10802] [2015] [4] [20] [0] [15] [15.2000]
ans =
[10802] [2015] [4] [20] [0] [30] [15.2000]
ans =
...
ans =
[10802] [2015] [5] [1] [1] [30] [180.3000]
ans =
[10802] [2015] [11] [1] [12] [15] [35.7300]
ans =
[10802] [2015] [11] [1] [12] [30] [35.7300]
ans =
[10802] [2015] [11] [1] [12] [45] [35.7300]
...
ans =
[10802] [2015] [11] [29] [23] [45] [67.1200]
ans =
[10802] [2015] [11] [30] [0] [0] [0x1 double]
ans =
[10802] [2015] [11] [30] [0] [15] [0x1 double]
ans =
[10802] [2015] [11] [30] [0] [30] [0x1 double]
...
ans =
[10802] [2015] [12] [11] [10] [45] [0x1 double]
ans =
Columns 1 through 6
[0x1 int32] [0x1 int32] [0x1 int32] [0x1 int32] [0x1 int32] [0x1 int32]
Column 7
[0x1 double]
>> fid=fclose(fid);
The last record is the EOF case...
Alternatively, you can
1. read the file into a cellstring array,
2. convert to character array which will pad the short records,
3. convert the fixed width substring fields in memory.
Or, an even better choice, avoid all this hassle and create a delimited, regular file format that can be parsed easily.
Here's another case where Fortran FORMAT wins, hands down--it would read the empty data field although would need fixed record length file.
More Answers (1)
per isakson
on 2 Jan 2016
Edited: per isakson
on 2 Jan 2016
It's a challenge to read files like yours with Matlab.
>> clear
>> [c1,sdn,c3,c4] = cssm( '010802_Q_1997.txt' );
>> whos
Name Size Bytes Class Attributes
c1 20256x1 81024 int32
c3 20256x1 162048 double
c4 20256x1 2286052 cell
sdn 20256x1 162048 double
where
function [c1,sdn,c3,c4] = cssm( filespec )
fmt = '%6c%25c%9c%[^\n]';
fid = fopen( filespec );
cac = textscan( fid, fmt, 'Headerlines',18, 'Whitespace','' );
fclose( fid );
c1 = textscan( cac{1}', '%6d' );
c1 = c1{:};
sdn = datenum( cac{2}, 'yyyy/mm/dd HH:MM' );
str = permute( cac{3}, [2,1] );
ise = arrayfun( @(ix) all(isspace(str(:,ix))), (1:length(str)) );
str( 7:9, ise ) = repmat( permute( 'nan', [2,1] ), 1, sum(ise) );
c3 = textscan( str, '%9f' );
c3 = c3{:};
c4 = strtrim(cac{4});
end
See Also
Categories
Find more on Text Data Preparation in Help Center and File Exchange
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!