How to load numbers from a text file to a .mat file?

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Sweet Nemesis
Sweet Nemesis 2022-1-6
评论： Voss 2022-1-6
I have a text file in the following format. How can I load it to a .mat file in its present form?
5
3
3 2 3 4
2 -1 5
3 1 -3 -4
  4 个评论
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Walter Roberson
Walter Roberson 2022-1-6
The only way to get it "exactly like it comes from the file" is in text form.
MATLAB does not have any way to represent arrays that have varying numbers of columns per row (or varying number of rows per column.) There is no way, in MATLAB, to represent "holes" -- you cannot, for example, have a matrix
3 2 3 4
2 -1 5 <hole>
3 1 -3 -4
The closest you can get would be to put NaN in the empty locations.
Sweet Nemesis
Sweet Nemesis 2022-1-6
I am ok with filling the missing values with zero or NaN to make a square matrix. How is that accomplished?

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采纳的回答

Walter Roberson
Walter Roberson 2022-1-6
Ran in:
filename = 'https://www.mathworks.com/matlabcentral/answers/uploaded_files/855395/text.txt';
data = readmatrix(filename)
data = 3×4
3 2 3 4 2 -1 5 NaN 3 1 -3 -4
  2 个评论
Sweet Nemesis
Sweet Nemesis 2022-1-6
Thank you! Is there a way to get the first two lines included in the matrix?
Walter Roberson
Walter Roberson 2022-1-6
Ran in:
filename = 'https://www.mathworks.com/matlabcentral/answers/uploaded_files/855395/text.txt';
opts = detectImportOptions(filename);
opts.DataLines = [1 inf];
data = readmatrix(filename, opts)
data = 5×4
5 NaN NaN NaN 3 NaN NaN NaN 3 2 3 4 2 -1 5 NaN 3 1 -3 -4

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更多回答（2 个）

Mathieu NOE
Mathieu NOE 2022-1-6
hi
maybe this
(I assumed you want each individual value stored in a cell)
the cell array can be of course saved to a mat file
a = readcell('data.txt',"Delimiter"," ")
a = 5×4 cell array
{[5]} {1×1 missing} {1×1 missing} {1×1 missing}
{[3]} {1×1 missing} {1×1 missing} {1×1 missing}
{[3]} {[ 2]} {[ 3]} {[ 4]}
{[2]} {[ -1]} {[ 5]} {1×1 missing}
{[3]} {[ 1]} {[ -3]} {[ -4]}
save test.mat a
Voss
Voss 2022-1-6
Ran in:
You can read the file into a character array called text and save it to a .mat file:
% read characters from text file:
fid = fopen('text.txt');
text = fread(fid,'*char').';
fclose(fid);
% save to mat:
save('text.mat','text');
Then load the .mat file to check that it is the same as the text file:
S = load('text.mat');
disp(S.text);
5 3 3 2 3 4 2 -1 5 3 1 -3 -4

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