Main Content


Size of Map object




dictionary is recommended over containers.Map because it accepts more data types as keys and values and provides better performance. (since R2022b)

n = size(M,1) returns the number of key-value pairs in the input Map object. size(M,1) is equivalent to length(M) and to the property M.Count.

szdim = size(M,dim) returns the length of dimension dim. Since a Map object stores data as an n-by-1 set of key-value pairs, size returns 1 when dim > 1.


sz = size(M) returns a two-element vector [n 1], where n is the number of key-value pairs in M.

[sz1,sz2,...,szL] = size(M) returns [n,1,...,1].


collapse all

Create a Map object.

months = {'Jan','Feb','Mar','Apr'};
rainfall = [327.2 368.2 197.6 178.4];
M = containers.Map(months,rainfall)
M = 
  Map with properties:

        Count: 4
      KeyType: char
    ValueType: double

Return the number of key-value pairs.

n = size(M,1)
n = 4

Return the number of pairs as a vector.

sz = size(M)
sz = 1×2

     4     1

Input Arguments

collapse all

Input Map object.

Queried dimension, specified as a positive numeric scalar.

Version History

Introduced in R2008b