How fprintf cell array and martix?
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I want to fprintf a cell array and a matrix to a txt file. I used the following code, but got the wrong result.
xx={'2017032312_8953';'2017032312_8978'};
yy=[10;11];
fprintf('%s %e \n ',xx{:}, yy)
The results is:
2017032312_8953 5.000000e+01
017032312_8978 1.000000e+01
I want the result like this:
2017032312_8953 1.0E+01
2017032312_8978 1.1e+01
How can this problem be solved? Many thanks!
采纳的回答
per isakson
2017-9-5
编辑：per isakson
2017-9-6
xx={'2017032312_8953';'2017032312_8978'};
yy=[10;11];
for jj = 1 : length( xx )
fprintf( '%s %3.1E \n', xx{jj}, yy(jj) )
end
outputs
2017032312_8953 1.0E+01
2017032312_8978 1.1E+01
Comparison of elapse times of loop codes and the vectorized code by Stephen Cobeldick
"It is better, since my data is huge." "Huge" implies that you want to write to a text file.
Here is a test on R2016a 64bit, Win7 and an old vanilla desktop.
>> et = cssm(1e4)
et =
8.4265 0.6577 0.1814
The difference between the first and the second elapse time value illustrates the influence of automatic flushing on speed. (Both are based on for-loops.) See Improving fwrite performance at Undocumented Matlab by Yair Altman. The third value is the elapse time of the vectorized code by Stephen Cobeldick.
The test is done with this function
function et = cssm(N)
xx = repmat( {'2017032312_8953';'2017032312_8978'}, N,1 );
yy = repmat( [10;11], N, 1 );
tic
fid = fopen( 'test1.txt', 'w' );
for jj = 1 : length( xx )
fprintf( fid, '%s %3.1E \n', xx{jj}, yy(jj) );
end
fclose( fid );
et = toc;
tic
fid = fopen( 'test2.txt', 'W' );
for jj = 1 : length( xx )
fprintf( fid, '%s %3.1E \n', xx{jj}, yy(jj) );
end
fclose( fid );
et(end+1) = toc;
tic
C = xx.';
C(2,:) = num2cell(yy);
fid = fopen( 'test3.txt', 'W' );
fprintf( fid, '%s %3.1E \n', C{:});
fclose( fid );
et(end+1) = toc;
end
更多回答（1 个）
Avoiding the for loop is quite easy too:
C = xx.';
C(2,:) = num2cell(yy);
fprintf('%s %3.1E \n', C{:})
which prints:
2017032312_8953 1.0E+01
2017032312_8978 1.1E+01
2 个评论
Qingsheng Bai
2017-9-5
Stephen23
2017-9-5
@Qingsheng Bai: I hope that it helps. You can also vote for my answer if it was useful for you.
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