How can I use textscan without delimiter?

Question

Jung-Woo 2015-6-10

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https://ww2.mathworks.cn/matlabcentral/answers/223196-how-can-i-use-textscan-without-delimiter

评论： Jung-Woo 2015-6-10

Let's say some numeric data is not delimited, buth we can delimit it based on their location. For example, I would like to read the following data using textscan:

 950 99810251026 999 496
 951 999102610271000 785
 9521000102710281001 497
 9531001102810291002 498
10001061108410851062 438
10011062108510861063 439

my code is:

cell2mat(textscan(fid, '%4f%4f%4f%4f%4f%4f'));

and the result is:

9981  251   26  999 496
9991  261  271    0 785
  1  271  281    1 497
 11  281  291    2 498
1061 1084 1085 1062 438
1062 1085 1086 1063 439

but what I wanted is:

998 1025 1026  999  496
999 1026 1027 1000  785
1000 1027 1028 1001  497
1001 1028 1029 1002  498
1061 1084 1085 1062  438
1062 1085 1086 1063  439

What's wrong with my code?

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Answer 1

per isakson 2015-6-10

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编辑：per isakson 2015-6-10

在 MATLAB Online 中打开

Must be done in two steps

read as character to avoid the white-space-magic
convert to numerical

fid = fopen( 'cssm.txt' );
cac = textscan( fid, '%4c%4c%4c%4c%4c%4c', 'Whitespace', '' );
fclose( fid );
buf = cellfun( @(str) str2num( str ), cac, 'uni', false );
cell2mat( buf )

outputs

ans =
         950         998        1025        1026         999         496
         951         999        1026        1027        1000         785
         952        1000        1027        1028        1001         497
         953        1001        1028        1029        1002         498
        1000        1061        1084        1085        1062         438
        1001        1062        1085        1086        1063         439

The last line of the text file needs to be terminated by a new-line-character(?)

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Jung-Woo 2015-6-10

Thank you so much. It works.

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Answer 2

Walter Roberson 2015-6-10

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https://ww2.mathworks.cn/matlabcentral/answers/223196-how-can-i-use-textscan-without-delimiter#answer_182193

在 MATLAB Online 中打开

str2double( textscan(fid, repmat('%4c',1,6)) )

The mistake in your code is that the counts for %4f do not start until the first non-blank character of the field. ' 1234567' with '%4f' format skips the blank and counts the 4 from '1' grabbing '1234'.

It is tempting to try to use 'Whitespace', '' so that it doesn't skip blanks. Unfortunately, when reading from a file, the numeric formats fail if they are required to start parsing from a blank instead of starting from a number-forming character (digit, + or -, decimal).