How to read every nth line of a file

time,n0v_soma,n1v_soma,n2v_soma,n3v_dend

0,-70,-70,-66.5,-66.5

0.027,-69.9703,-69.9794,-66.4966,-66.4966

0.054,-69.9685,-69.9533,-66.4933,-66.4933

0.081,-69.9283,-69.9322,-66.49,-66.4899

0.108,-69.9588,-69.9385,-66.4866,-66.4866

0.135,-69.9422,-69.8965,-66.4833,-66.4833

0.162,-69.9058,-69.8943,-66.48,-66.48

0.189,-69.8465,-69.8618,-66.4767,-66.4766

0.216,-69.8505,-69.8258,-66.4734,-66.4733

0.243,-69.7855,-69.8011,-66.4701,-66.47

0.27,-69.7913,-69.7594,-66.4668,-66.4667

0.297,-69.7228,-69.7291,-66.4636,-66.4634

0.324,-69.6841,-69.7006,-66.4603,-66.4601

0.351,-69.6907,-69.7157,-66.4571,-66.4569

0.378,-69.6584,-69.7295,-66.4538,-66.4536

0.405,-69.5766,-69.7279,-66.4506,-66.4503

0.432,-69.5668,-69.6756,-66.4474,-66.447

0.459,-69.5396,-69.6777,-66.4442,-66.4437

0.486,-69.511,-69.6717,-66.441,-66.4404

0.513,-69.4808,-69.6523,-66.4378,-66.4371

0.54,-69.4632,-69.6325,-66.4346,-66.4339

0.567,-69.4605,-69.6169,-66.4314,-66.4306

0.594,-69.4398,-69.6346,-66.4282,-66.4273

0.621,-69.4638,-69.6245,-66.4251,-66.424

0.648,-69.4429,-69.5968,-66.4219,-66.4207

0.675,-69.4134,-69.5639,-66.4187,-66.4174

0.702,-69.3973,-69.5655,-66.4156,-66.4141

0.729,-69.3973,-69.5668,-66.4125,-66.4108

0.756,-69.3611,-69.6189,-66.4093,-66.4075

My file looks something like this. I want to read every 10th line of this and skip the header.

so

my array should look like this

C=[0.216,-69.8505,-69.8258,-66.4734,-66.4733;0.486,-69.511,-69.6717,-66.441,-66.4404;0.756,-69.3611,-69.6189,-66.4093,-66.4075];

and so on

Answer 1

[Walter Roberson]

Sometimes it is just easier to loop reading and discarding most lines and storing the ones you want.

But if you need it done in one step:

per_line = 5;
every_nth_line = 10;
fmt = [repmat('*%f', 1, per_line*(every_nth_line-1)), repmat('%f', 1, per_line)];

fid = fopen('YourFile.txt', 'rt');
datacell = textscan(fid, fmt, 'delimiter', ',\n', 'HeaderLines', 1, 'CollectOutput', 1);
fclose(fid);
C = datacell{1};

[Shivik Garg]

I tried running the script it returns the C matrix as 'empty matrix:0 by 50' It didnt give the answer I was hoping.

[Walter Roberson]

Sorry, minor typo. Change

fmt = [repmat('*%f', 1, per_line*(every_nth_line-1)), repmat('%f', 1, per_line)];

to

fmt = [repmat('%*f', 1, per_line*(every_nth_line-1)), repmat('%f', 1, per_line)];

[Shivik Garg]

It worked. Thanks a lot for you help