Help with the fscanf function

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AMZ
AMZ 2022-11-10
编辑： Walter Roberson 2022-11-10
Hello Community,
I have been trying to figure out how I can use the fscanf functions to input data:
4 6
5.2 1.3
6.2 8.8
4.9 6.9
10.2 1.2
In this format:
A B
K1 J1
K2 J2
K3 J3
K4 J4
i.e. A = 4, B = 6, K1 = 5.2 etc..

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Walter Roberson
Walter Roberson 2022-11-10
Ran in:
Call fscanf() with size parameter [2, inf] and use .' to transpose the output to N x 2
S = ...
"4 6" + newline + ...
"5.2 1.3" + newline + ...
"6.2 8.8" + newline + ...
"4.9 6.9" + newline + ...
"10.2 1.2"
S =
"4 6 5.2 1.3 6.2 8.8 4.9 6.9 10.2 1.2"
data = sscanf(S, '%f %f', [2 inf]) .'
data = 5×2
4.0000 6.0000 5.2000 1.3000 6.2000 8.8000 4.9000 6.9000 10.2000 1.2000
  2 个评论
AMZ
AMZ 2022-11-10
Oh thanks Walter.
I forgot to mention the values are present in a Text file say "values.txt", How do I:
  • import the values from the file?
  • How do I then assign to those variables?
Walter Roberson
Walter Roberson 2022-11-10
编辑：Walter Roberson 2022-11-10
Ran in:
%in your real code you would use a real file name
filename = tempname() + ".txt";
%preparation -- need to write some data into the file in order
%to illustrate reading data from a file
%this section exists only for demonstration purposes.
%in your real code you would skip this section and just assign to the
%filename and then do the fopen and so on
S = ...
"4 6" + newline + ...
"5.2 1.3" + newline + ...
"6.2 8.8" + newline + ...
"4.9 6.9" + newline + ...
"10.2 1.2";
fid = fopen(filename, 'w');
fwrite(fid, S);
fclose(fid);
%now the actual work that you would have in your real file
fid = fopen(filename, 'r');
data = fscanf(fid, '%f %f', [2 inf]) .';
fclose(fid);
data
data = 5×2
4.0000 6.0000 5.2000 1.3000 6.2000 8.8000 4.9000 6.9000 10.2000 1.2000
and if using fscanf() is not a hard requirement being imposed by someone else, then skip the fopen() and so on, and just use
data = readmatrix(filename)
data = 5×2
4.0000 6.0000 5.2000 1.3000 6.2000 8.8000 4.9000 6.9000 10.2000 1.2000

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