Matlab to read in fix-width text file - matlab

Question

I have a text file like below:
TestData
6.84 11.31 17.51 22.62 26.91 31.98 36.47 35.85 28.47 20.57 10.50 6.37 test1
0.24 2.62 4.94 7.17 10.39 15.37 18.73 18.29 12.26 6.46 1.15 -0.33 test2
68.47 95.04156.07218.39304.31320.22311.69269.22203.01135.60 68.18 55.09 test3
68.47 95.04156.07218.39304.31320.22311.69269.22203.01135.60 68.18 55.09 test4
...
As you can see, the first two lines are comments to ignore. In the following lines, there is a comment at the end of each line too. Each number is in the form of %6f. Also, there are blank lines in between.
I want to read in all the numbers into a matrix to make plots. I tried to use textscan, but had problems to ignore the last column, the blank lines and read in numbers that are connected (e.g., some numbers in the line: test4).
Here is the code I have by now:
data=dir('*.txt');
formatspecific='%6f%6f%6f%6f%6f%6f%6f%6f%6f%6f%6f%6f';
for i=1:length(data);
TestData1=data(i).name;
tempData=textscan(TestData1,formatspecific,'HeaderLines',2);
end
Anybody can help to make a sample code to improve the textscan part?

Answer 1

To use textscan to read a file, you have to "open" it before calling textscan and "close" it after; you should use
fopen to open the input file
fclose to close the input file
textscan returns a cellarray with the content read from the input file; since you are reading more than one file, you should change the way you manage the cellarray returned by textscan, actually, as it is now in your code, the data are overwritten at each iteration.
One possibility could be to store the data in an array of struct with, for example, 2 fields: the name of the input file and the data.
Another possibility could be to generate a struct whos each fields contains the data read from the input file; you can automatically generate the name of the fileds.
Another one possibility could be to store them into a a matrix.
Hereafter, you can find a script in which these three alternative have been implemented.
Code Updated (following the comment received)
In order to be able to correctly read data such as 95.04156.07 as 95.04 156.07, the format specifier should be modified from %6f to %6.2f
% Get the list of input data
data=dir('input_file*.txt');
% Define the number of data column
n_data_col=12;
% Define the number of heared lines
n_header=2;
% Build the format specifier string
% OLD format specifier
formatspecific=[repmat('%6f',1,n_data_col) '%s']
% NEW format specifier
formatspecific=[repmat('%6.2f',1,n_data_col) '%s']
% Initialize the m_data matrix (if you know in advance the numer of row of
% each input file yoiu can define since the beginning the size of the
% matrix)
m_data=[];
% Loop for input file reading
for i=1:length(data)
% Get the i-th file name
file_name=data(i).name
% Open the i-th input file
fp=fopen(file_name,'rt')
% Read the i-th input file
C=textscan(fp,formatspecific,'headerlines',n_header)
% Close the input file
fclose(fp)
% Assign the read data to the "the_data" array struct
the_data(i).f_name=file_name
the_data(i).data=[C{1:end-1}]
% Assign the data to a struct whos fileds are named after the inout file
data_struct.(file_name(1:end-4))=[C{1:end-1}]
% Assign the data to the matric "m_data
m_data=[m_data;[C{1:end-1}]]
end
Input file
TestData
6.84 11.31 17.51 22.62 26.91 31.98 36.47 35.85 28.47 20.57 10.50 6.37 test1
0.24 2.62 4.94 7.17 10.39 15.37 18.73 18.29 12.26 6.46 1.15 -0.33 test2
68.47 95.04156.07218.39304.31320.22311.69269.22203.01135.60 68.18 55.09 test3
68.47 95.04156.07218.39304.31320.22311.69269.22203.01135.60 68.18 55.09 test4
Output
m_data =
Columns 1 through 7
6.8400 11.3100 17.5100 22.6200 26.9100 31.9800 36.4700
0.2400 2.6200 4.9400 7.1700 10.3900 15.3700 18.7300
68.4700 95.0400 156.0700 218.3900 304.3100 320.2200 311.6900
68.4700 95.0400 156.0700 218.3900 304.3100 320.2200 311.6900
Columns 8 through 12
35.8500 28.4700 20.5700 10.5000 6.3700
18.2900 12.2600 6.4600 1.1500 -0.3300
269.2200 203.0100 135.6000 68.1800 55.0900
269.2200 203.0100 135.6000 68.1800 55.0900
Hope this helps.