Concatenating a cell array

Given: A cell array with names where names={'Harry','Xavier','Sue'};

Find: How to concantenate a '1' at the end of each character array using a for-loop and the strcat function, among others.

Issue: I am utterly confused on what this is asking and why. I am assuming it's just practice concatenating but I have only really done this in excel.

My solution: Being unfamiliar with this in MATLAB, I don't really know where to start but I tried:

CAT=strcat(ones(Names));
% Got an error here: Size inputs must be numeric.

So If I can't use the ones function, how else can I approach this for that part of the question?

[Stephen23]

names = {'Harry','Xavier','Sue'};
strcat(names,'1')

ans = 1x3 cell array
    {'Harry1'}    {'Xavier1'}    {'Sue1'}

[Aquatris]

ones() function creates an array of 1s with the size of an integer argument(s) you give to it, not what you want

A = ones(3)

A = 3x3

1 1 1 1 1 1 1 1 1

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A = ones(1,3)

A = 1x3

1 1 1

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[Spaceman]

@Stephen23 I feel like the idiot who is pushing on a pull door when I code sometimes! XD

Thank you.

[Spaceman]

@Aquatris Thank you for that clarification. I was trying to brute force the ones() function to do something it was not intended to do. I was literally pushing a sqaure peg into a round hole.

Answer 1

[Rik]

The assignment tells you to use a for loop. So even if it can be solved without one, let's do it. But before we can do that, we need to figure out what we want to do in each iteration. That's easy: we want to do something with each element, so let's write a loop that helps us do that:

names = {'Harry','Xavier','Sue'};
for n=1:numel(names)
    
end

So now we have a loop. The next step is to add '1' to each element. While we could use square brackets, we can use the strcat function as well. If you don't know what to do, you need to read the documentation for this function:

help strcat % use doc instead of help to open the documentation browser

 strcat - Concatenate strings horizontally
    This MATLAB function horizontally concatenates the text in its input
    arguments.

    Syntax
      s = strcat(s1,...,sN)

    Input Arguments
      s1,...,sN - Input text
        character arrays | cell array of character vectors | string arrays

    Examples
      openExample('matlab/ConcatenateTwoStringsExample')
      openExample('matlab/ConcatenateTwoCellArraysExample')
      openExample('matlab/ConcatenateTwoCellArrayswithScalarCellArrayExample')
      openExample('matlab/ConcatenateTwoStringArraysExample')

    See also append, plus, cat, vertcat, horzcat, cellstr, strjoin, join

    Introduced in MATLAB before R2006a
    Documentation for strcat
       doc strcat

    Other uses of strcat

       cell/strcat    string/strcat

After reading this (in the documentation browser), you can simply adapt the example given:

strcat(names{n},'1')

ans = 'Sue1'

% note the {} to get the content of the cell
% () would give you the cell itself, not the contents

The final piece of the puzzle is to store it back in the original array:

names = {'Harry','Xavier','Sue'};
for n=1:numel(names)
    names{n} = strcat(names{n},'1');
end
names

names = 1x3 cell array
    {'Harry1'}    {'Xavier1'}    {'Sue1'}

If you want to be a smart-ass, you can satisfy the requirement of a for loop AND vectorize your code. Your teacher will either love you or hate you.

names = {'Harry','Xavier','Sue'};
for n=1
    names = strcat(names,'1');
end
names

names = 1x3 cell array
    {'Harry1'}    {'Xavier1'}    {'Sue1'}

[Spaceman]

Eureka! This is a thing of beauty. I'm new to cells in MATLAB, as well as the nume1 & strcat functions so a bit tricky for me to use them in loops without exmaples like yours. Is there a way to use a for-loop to concatenate the '1' at the end WITHOUT using the strcat function in the loop?

[Stephen23]

"Is there a way to use a for-loop to concatenate the '1' at the end WITHOUT using the strcat function in the loop?"

Of course. This is MATLAB, which you should always remember is based on arrays, so some array operations could do something similar, e.g. indexing or concatenation:

names = {'Harry','Xavier','Sue'};
for k = 1:numel(names)
    names{k}(end+1) = '1';     % indexing
    names{k} = [names{k},'2']; % concatenation
end
names

names = 1x3 cell array
    {'Harry12'}    {'Xavier12'}    {'Sue12'}

The name MATLAB comes from "MATrix LABoratory": thinking in terms of matrices and arrays helps to use MATLAB.

[Spaceman]

Thank you, this is beautiful.