matlab string arrays

Question

I have a list of files that I would like analyze. They are all named chr1.fa, chr2.fa, ... , chr22.fa, chrX.fa

I would like to store all of these filenames in an array. I know in python you can do

files = ["chr"+str(x)+".fa" for x in range(1,22)]+["chrX.fa"]

I have been having an embarrassingly difficult time trying to do the equivalent in Matlab. Otherwise, I'll have to initialize the file like:

files = {'chr1.fa','chr2.fa',...,'chr22.fa','chrX.fa'}

Which is really not ideal since I may be processing more files.

Any pointers on where I should be looking would be greatly appreciated.

Thanks!

Phonon · Accepted Answer · 2012-06-19 20:47:50Z

3

This isn't exactly as compact as Python, but it'll do the job for you.

N = 20;

prefix = 'chr';
suffix = '.fa';

names = cell(N,1);

for n = 1:N
    names{n} = [prefix int2str(n) suffix];
end

names{N+1} = [prefix 'X' suffix];

You can fetch names by names{index}. Note the curly braces, since this is a cell array, not a multidimensional character array.

answered Jun 19, 2012 at 20:47

Phonon

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1 Comment

tmpearce Over a year ago

@Jamie, it's polite to upvote good answers and eventually "accept" the one you feel is best once you feel the question has been answered (and the option becomes available).

Jonas · Accepted Answer · 2012-06-19 23:18:35Z

3

Here's a more concise version using sprintf and strsplit:

files = strsplit(sprintf('chr%i.fa ',1:22),' ');

files{end} = 'chrX.fa';

answered Jun 19, 2012 at 23:18

Jonas

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Comments

tmpearce · Accepted Answer · 2012-06-19 20:59:54Z

2

Here's a one-liner, just for fun. @Phonon's way works too obviously.

 files = [arrayfun(@(x)strcat('chr',num2str(x),'.fa'),(1:22)','uni',0); 'chrX.fa']

answered Jun 19, 2012 at 20:59

tmpearce

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Amro · Accepted Answer · 2012-06-21 08:57:48Z

1

Try:

files = [strtrim(cellstr(num2str((1:22)','chr%d.fa'))) ; 'chrX.fa']

answered Jun 21, 2012 at 8:57

Amro

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matlabbit · Accepted Answer · 2018-01-18 21:21:04Z

0

Old topic, but starting in 16b, using the new string datatype makes this pretty easy:

>> files = ["chr" + (1:22) + ".fa", "chrX.fa"]'

files = 

  23×1 string array

    "chr1.fa"
    "chr2.fa"
    "chr3.fa"
    "chr4.fa"
    "chr5.fa"
    "chr6.fa"
    "chr7.fa"
    "chr8.fa"
    "chr9.fa"
    "chr10.fa"
    "chr11.fa"
    "chr12.fa"
    "chr13.fa"
    "chr14.fa"
    "chr15.fa"
    "chr16.fa"
    "chr17.fa"
    "chr18.fa"
    "chr19.fa"
    "chr20.fa"
    "chr21.fa"
    "chr22.fa"
    "chrX.fa"

answered Jan 18, 2018 at 21:21

matlabbit

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