How to change the format of input .txt files?

Hello,

I have a question about a code. I have multiple .txt files with a specific format. Specifically , exh file has 1 header, and 4 columns with 1 tab space between each other (the 4th column has an alphanumeric format, and columns 1-3 are numbers).

I would like to change the given format, which is f7.3 1x f7.3 1x f3.1 1x character to the following

1x f6.3 4x f6.3 4x 3.1 1x character (x is tab (space) and f is float (real) number).

I am attaching an input file as an example...

Could you please help me?

Answer 1

[Walter Roberson]

You may have to read the header separately. Then readtable. Then I suggest you use compose() passing in a string() object as the format. Then write the strings to a file, possibly strjoin and fwrite

[Ivan Mich]

I am using the following code

clc
clear

filename1= 'input_file_test.txt'; 
d1=readtable(filename1);
formatSpec=" %6.3d    %6.3d    %3.1d %d"
str=compose(formatSpec,d1)

but command window shows :

Error using compose (line 98)

Unable to convert 'table' value to 'int64'.

Error in Untitled (line 9)

str=compose(formatSpec,d1)

How can I fix it?

[Walter Roberson]

filename1 =  'input_file_test.txt'; 
d1 = readtable(filename1, 'ReadVariableNames', false);
formatSpec = "\t%6.3d\t\t\t\t%6.3d\t\t\t\t%3.1d\t%s"
str = compose(formatSpec, d1{:,1}, d1{:,2}, d1{:,3}, d1{:,4});
ss = strjoin(str, "\n");

fid = fopen(OutputFile, 'w') ;
 %write any header at this point

   %then
   fwrite(fid, ss) ;
   fclose(fid) ;

[Ivan Mich]

thank you but there is a problem...command window shows me

Error using compose

Function is not defined for 'cell' inputs.

Error in Untitled (line 7)

str = compose(formatSpec, d1{:,1}, d1{:,2}, d1{:,3}, d1{:,4});

Is there something else to try ?

[Walter Roberson]

str = compose(formatSpec, d1{:,1}, d1{:,2}, d1{:,3}, string(d1{:,4}));

[Ivan Mich]

I am sorry but it is no use..

command window still show:

Error using compose

Function is not defined for 'cell' inputs.

Error in Untitled (line 7)

str = compose(formatSpec, d1{:,1}, d1{:,2}, d1{:,3}, string(d1{:,4}));

Could you please help me?

[Ivan Mich]

I have also tried

clc
clear
filename1 =  'input_file_test.txt'; 
d1 = readtable(filename1, 'ReadVariableNames', false);
formatSpec = "\t%6.3d\t\t\t\t%6.3d\t\t\t\t%3.1d\t%s";
str = compose(formatSpec, d1(:,1), d1(:,2), d1(:,3), string(d1{:,4}));
ss = strjoin(str, "\n");
fid = fopen(OutputFile, 'w') ;
 %write any header at this point
   %then
   fwrite(fid, ss) ;
   fclose(fid) ;

but it is not working, as command window shows me

Error using compose (line 98)

Unable to convert 'table' value to 'int64'.

Error in Untitled (line 8)

str = compose(formatSpec, d1(:,1), d1(:,2), d1(:,3), string(d1{:,4}));

Could you please help me?

[Walter Roberson]

I tested the following on my system.

filename1 =  'input_file_test.txt'; 
OutputFile = 'output_file_test.txt';

d1 = readtable(filename1, 'ReadVariableNames', false);
formatSpec = "\t%6.3d\t\t\t\t%6.3d\t\t\t\t%3.1d\t%s"
str = compose(formatSpec, d1{:,1}, d1{:,2}, d1{:,3}, string(d1{:,4}));
ss = strjoin(str, newline);

fid = fopen(OutputFile, 'w') ;
 %write any header at this point

   %then
   fwrite(fid, ss) ;
   fclose(fid) ;

[Ivan Mich]

Thank you @Walter Roberson for your help, but it is no use. Command window shows me the same message:

Error using compose

Function is not defined for 'cell' inputs.

Error in Untitled (line 9)

str = compose(formatSpec, d1{:,1}, d1{:,2}, d1{:,3}, string(d1{:,4}));

I am supposing that problem is in "compose" command...

[Walter Roberson]

Please show

class(d1{:,1})
class(d1{:,2}) 
class(d1{:,3}) 
class(d1{:,4})
class(string(d1{:,4}))
Also please remind us while matlab version you are using.

[Ivan Mich]

well

ans =
'cell'
ans =
'cell'
ans =
'cell'
ans =
'cell'
ans =
'string'

I am using 2019a matlab version...