MATLAB Answers

How Can I Save a Struct Array to a Text File?

2 views (last 30 days)
Paul
Paul on 4 Oct 2020
Answered: Ameer Hamza on 4 Oct 2020
I have a struct array. Each field in the struct arrray is a column vector, and the column vectors are of unequal lengths.
s(1).t=[1;2];s(1).x=[10;20];s(2).t=[21;22;23];s(2).x=[100;101;102];
My goal is save the data in s to a text file with the elements of each field in s vertically concatenated. The file should look like this:
>> type file1.txt
t,x
1,10
2,20
21,100
22,101
23,102
I thought that struct2table followed by writetable might give me what I want. But, consistent with its doc page, struct2table doesn't do the vertical concatenation the way I hoped it would:
tbl=struct2table(s)
tbl =
2×2 table
t x
____________ ____________
[2×1 double] [2×1 double]
[3×1 double] [3×1 double]
At present my solution is as follows:
for ii=1:2,s(ii).t = s(ii).t.'; s(ii).x = s(ii).x.';end
snew.t=[s.t].'; snew.x=[s.x].';
tblnew=struct2table(snew)
tblnew =
5×2 table
t x
__ ___
1 10
2 20
21 100
22 101
23 102
And then I can witetable(tnew).
After I typed all that up, I did find a better way:
s(1).t=[1;2];s(1).x=[10;20];s(2).t=[21;22;23];s(2).x=[100;101;102];
C=arrayfun(@(x) struct2table(x),s,'UniformOutput',false);
vertcat(C{:})
ans =
5×2 table
t x
__ ___
1 10
2 20
21 100
22 101
23 102
These two lines aren't too bad, except for the need to create the intermediate variable C. Is there an easier and/or better way to write my original struct array to a text file? If it makes it any easier, I may not need the column headings in the text file.
Comment: According the doc in my release, the result of struct2table for a 1 x 2 struct array input is not defined. But, as shown, it worked fine and returned the same result as for a 2 x 1 struct array input..

  0 Comments

Sign in to comment.

Accepted Answer

Ameer Hamza
Ameer Hamza on 4 Oct 2020
You can directly create a matrix
M = cell2mat(struct2cell(s(:)).')
writematrix(M, 'filename.txt')

  0 Comments

Sign in to comment.

More Answers (0)

Products


Release

R2019a

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!