Cell Arrays of Character Vectors

To store text as a character vector, enclose it single quotes. Typically, a character vector has text that you consider to be a single piece of information, such as a file name or a label for a plot. If you have many pieces of text, such as a list of file names, then you can store them in a cell array. A cell array whose elements are all character vectors is a cell array of character vectors.

Note

  • As of R2018b, the recommended way to store text is to use string arrays. If you create variables that have the string data type, store them in string arrays, not cell arrays. For more information, see Text in String and Character Arrays and Update Your Code to Accept Strings.

  • While the phrase cell array of strings frequently has been used to describe such cell arrays, the phrase is no longer accurate because such a cell array holds character vectors, not strings.

Create Cell Array of Character Vectors

To create a cell array of character vectors, use curly braces, {}, just as you would to create any cell array. For example, use a cell array of character vectors to store a list of names.

C = {'Li','Sanchez','Jones','Yang','Larson'}
C = 1x5 cell array
    {'Li'}    {'Sanchez'}    {'Jones'}    {'Yang'}    {'Larson'}

The character vectors in C can have different lengths because a cell array does not require that its contents have the same size. To determine the lengths of the character vectors in C, use the strlength function.

L = strlength(C)
L = 1×5

     2     7     5     4     6

Access Character Vectors in Cell Array

To access character vectors in a cell array, index into it using curly braces, {}. Extract the contents of the first cell and store it as a character vector.

C = {'Li','Sanchez','Jones','Yang','Larson'};
chr = C{1}
chr = 
'Li'

Assign a different character vector to the first cell.

C{1} = 'Yang'
C = 1x5 cell array
    {'Yang'}    {'Sanchez'}    {'Jones'}    {'Yang'}    {'Larson'}

To refer to a subset of cells, instead of their contents, index using smooth parentheses.

C(1:3)
ans = 1x3 cell array
    {'Yang'}    {'Sanchez'}    {'Jones'}

While you can access the contents of cells by indexing, most functions that accept cell arrays as inputs operate on the entire cell array. For example, you can use the strcmp function to compare the contents of C to a character vector. strcmp returns 1 where there is a match and 0 otherwise.

TF = strcmp(C,'Yang')
TF = 1x5 logical array

   1   0   0   1   0

You can sum over TF to find the number of matches.

num = sum(TF)
num = 2

Use TF as logical indices to return the matches in C. If you index using smooth parentheses, then the output is a cell array containing only the matches.

M = C(TF)
M = 1x2 cell array
    {'Yang'}    {'Yang'}

Convert Cell Arrays to String Arrays

As of R2018b, string arrays are supported throughout MATLAB® and MathWorks® products. Therefore it is recommended that you use string arrays instead of cell arrays of character vectors. (However, MATLAB functions that accept string arrays as inputs do accept character vectors and cell arrays of character vectors as well.)

You can convert cell arrays of character vectors to string arrays. To convert a cell array of character vectors, use the string function.

C = {'Li','Sanchez','Jones','Yang','Larson'}
C = 1x5 cell array
    {'Li'}    {'Sanchez'}    {'Jones'}    {'Yang'}    {'Larson'}

str = string(C)
str = 1x5 string array
    "Li"    "Sanchez"    "Jones"    "Yang"    "Larson"

In fact, the string function converts any cell array, so long as all of the contents can be converted to strings.

C2 = {5, 10, 'some text', datetime('today')}
C2=1×4 cell
    {[5]}    {[10]}    {'some text'}    {[26-Aug-2019]}

str2 = string(C2)
str2 = 1x4 string array
    "5"    "10"    "some text"    "26-Aug-2019"

See Also

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