read certain range in csv file and save to new file

Hi guys,

I have a one column data contain 100 000 rows.

i need to extract a data for range 0-0 and save it into new file.

example of my data:

0
1
2
3
4
5
0
6
7
4
3
5
6
0
6
43
5
7
5
0
7
4
60
0

Then, for a new file it should contains 0 1 2 3 4 5 0 in column , the second file is 0 6 7 4 3 5 6 0 and so on.

[dpb]

Is the file guaranteed to begin/end with 0 entry?

[louis za]

yes because it is speed profile

Answer 1

[Star Strider]

A loop is the only (and likely the simplest) option, since you need the zero values on both ends of each sub-vector:

V = [0
     1
     2
     3
     4
     5
     0
     6
     7
     4
     3
     5
     6
     0
     6
     43
     5
     7
     5
     0
     7
     4
     60
     0];

idx = find(V == 0);
for k1 = 1:numel(idx)-1
    Out{k1} = V(idx(k1):idx(k1+1));
end

[louis za]

how can i save the output, it in cell array

[Star Strider]

I would use the cell2table (link) function, then the writetable (link) function.

ST = cell2table(Out);
writetable(ST, 'YourFileName.txt');

Experiment to get the result you want.

[louis za]

thankyou for your help

[Star Strider]

As always, my pleasure.

Answer 2

[dpb]

Same basic solution but one can write the loop without an explicit loop -- of course, it could easily be found to be less efficient than the deadahead solution besides the complexity, but just as exercise:

idx=find(V == 0);
idx=reshape([idx(1);kron(idx(2:end-1),ones(2,1));idx(end)],2,[]);
out=arrayfun(@(i1,i2) V(i1:i2),idx(1,:),idx(2,:),'uni',0);