read a range of values using dlmread

Hi everybody,

I am using dlmwrite to write a vector into a .csv file. Then I would like to read only a certain range of this vector with dlmread. This is an example of my code:

% file tries.m

mins = 20; % length of recording in minutes
Fs = 512; % sample rate
a = zeros (1, mins*60*Fs); % create fake vector

dlmwrite ( 'data_raw.csv', a ); % write vector to csv file

v1 = dlmread ( 'data_raw.csv', ',', [0 0 mins*60*Fs-1 0] ); % read whole vector
v2 = dlmread ( 'data_raw.csv', ',', [1 0 mins*60*Fs-1 0] ); % read roffset = 1

When I read the whole vector (in v1) everything is fine. When I try to read starting from position 1 (in v2), I receive the following error:

Error using dlmread (line 139)
Badly formed format string.

Error in tries (line 8)
v2 = dlmread ( 'data_raw.csv', ',', [1 0 mins*60*Fs-1 0] );

Has anybody got any idea why this is happening? How can I successfully read only a range of values from the csv file?

Thank you very much, Costanzo

Answer 1

[Supreeth Subbaraya]

The "a" vector is exceeding in the number of columns a csv file can hold. You can store the vector as a column vector as opposed to a row vector in the csv and access it. To do this, write to the csv file as

>> dlmwrite('data_raw.csv',a').

Then you can access the values as given in the documentation here.

Also, you can consider the function csvread for reading and writing csv files. Documentation is available here