Skipping lines in datastore with read function

Question

Fernando Meneses 2021-8-3

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评论： Fernando Meneses 2021-8-6

Hello, I would like to access only to certain lines (rows) in my datastore and save them to a matrix. What I am doing now is:

1. Read all the datastore and save the data in a matrix.

2. Eliminate the data I don't want (by removing rows from the matrix).

It works, but I'm wasting a lot of time storing useless data in the first step. Is it a way to directly save the data that I want?

Information: my datastore is a collection of files, all of them with the same structure: two columns filled with numeric data. Each file has 100 rows, but I only want to save the first 60.

Thanks!

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Answer 1

Amogh Bhole 2021-8-6

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https://ww2.mathworks.cn/matlabcentral/answers/891727-skipping-lines-in-datastore-with-read-function#answer_762272

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As per my understanding you are interested in reading only the top 60 rows from each file. It can be done efficiently using “readcell” function.

For each file you can use the below code to read top 60 rows:

C = readcell(filename,'Range',1:60);

Then save it in the matrix.

You can refer to this link for more information.

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Fernando Meneses 2021-8-6

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Thanks Amogh!

I used this function but I had to make a small change because I had the following error with the Range:

C = readcell(filename,'Range',1:60);
ERROR:
A numeric range must be 1, 2, or 4 positive integers of the form:
    [start-row, start-column, end-row, end-column], where end>=start or
    [start-row, start-column] or
    [start-row].