How to use sprintf/fprintf to print a string inside a cell array in matlab?

Question

I was wondering if it was possible to use sprintf or fprintf to print something to a cell array.

In a structure A I have

A.labels = {'A' 'B' 'C' 'D'}

and I have a string/cell array

B = {'E' 'F' 'G' 'H'}

and I want to print into a new structure C such that I want

C.labels = {'A-E', 'B-F', 'C-G', 'E-H'}

In the code below I am just trying to check how to do the first entry and then once I figure that out I can do the rest myself.

C(1).labels = fprintf('%s -%s',B{1},A(1).labels);

But this does not do the job. How can I fix this?

@knedlsepp thanks for the edit.. sorry if it was annoying to read! — Maheen Siddiqui
– Maheen Siddiqui, Commented Feb 22, 2015 at 21:27

knedlsepp · Accepted Answer · 2015-02-22 21:37:25Z

2

If you type help fprintf it says:

fprintf - Write data to text file

But you want help sprintf:

sprintf - Format data into string

So you can fix your problem using:

C.labels = cellfun(@(x,y) sprintf('%s-%s',x,y), A.labels, B, 'uni',0)

This uses: cellfun to take corresponding pairs of A.labels and B and feeds it to the function @(x,y) sprintf('%s-%s',x,y), which uses sprintf.

You could also use a regular for loop of course. I want to add also that what you currently have is a structure with a single cell-entry of length four instead of four structures each having a single entry.

edited Feb 22, 2015 at 21:37

answered Feb 22, 2015 at 21:27

knedlsepp

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6 Comments

Maheen Siddiqui Over a year ago

Ah thanks.. I wasn't aware of this cellfun before.. thank you.

knedlsepp Over a year ago

@MaheenSiddiqui: You could use a for loop instead of cellfun. The most important fix here is, that you need to use sprintf instead of fprintf.

rayryeng Over a year ago

@knedlsepp - Have you considered using sprintfc? It's an undocumented function: undocumentedmatlab.com/blog/…

knedlsepp Over a year ago

@rayryeng: Never heard about it. I guess in this case strcat would suffice. So this is basically cellfun+sprintf for a single cell-array?

rayryeng Over a year ago

Pretty much! You haven't heard of it because it is undocumented after all :) lol. sprintfc is a very powerful function. It essentially takes data and converts it into a cell array of entries. It has been shown that it is much faster than using cellfun with uni=0.

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Luis Mendo · Accepted Answer · 2015-02-22 21:55:04Z

2

This can be done very simply with strcat:

C.labels = strcat(A.labels, '-', B);

answered Feb 22, 2015 at 21:55

Luis Mendo

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2 Comments

knedlsepp Over a year ago

Ha. Just when I write my comment about strcat, you turn up. :-D

Luis Mendo Over a year ago

Actually I turned up 13 seconds earlier :-P

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