mode — Most frequent value along a dimension with MATLAB-compatible tie semantics.

mode(A) returns the value that appears most frequently in A. When multiple values share the same maximum frequency, the smallest tied value is returned in M, matching MATLAB. Requesting [M, F, C] = mode(A) additionally yields the frequency of the mode and a cell array C whose entries are sorted column vectors of the tied values for each slice.

How mode works

• mode(A) reduces along the first non-singleton dimension of A.
• mode(A, dim) reduces along the specified dimension (1-based, >= 1).
• mode(A, 'all') collapses every element of A into a single scalar mode.
• [M, F, C] = mode(A, ...) additionally returns the frequency F of the mode (as a double) and a cell array C of sorted tied values per slice.
• Ties resolve to the smallest tied value in M, while C contains the full tied set sorted in ascending order.
• NaN entries are ignored. If a slice is entirely NaN (or empty), the corresponding M value is NaN, F is 0, and the cell entry is an empty 0 × 1 column.
• Logical, integer, and boolean inputs are promoted to double precision before counting frequencies.
• Dimensions larger than ndims(A) treat the input as having trailing singleton dimensions, so each slice contains a single element.

Examples

Mode of a vector with a clear majority

x = [1 2 2 3 3 3 4];
m = mode(x)

Expected output:

m = 3

Ties return the smallest value with the full sorted set

x = [1 1 2 2];
[m, f, c] = mode(x)

Expected output:

m = 1
f = 2
c = {[1; 2]}

Column-wise mode of a matrix

A = [1 2 1; 2 2 3; 2 4 3];
m = mode(A)

Expected output:

m = [2 2 3]

Mode along the second dimension

A = [1 2 1; 2 2 3; 2 4 3];
m = mode(A, 2)

Expected output:

m = [1; 2; 2]

Mode across every element

A = [1 2 3; 2 3 2];
m = mode(A, 'all')

Expected output:

m = 2

NaN values are ignored unless every element is NaN

x = [1 NaN 2 2 NaN];
[m, f] = mode(x)

Expected output:

m = 2
f = 2

FAQ

Related Stats functions

Open-source implementation

Unlike proprietary runtimes, every RunMat function is open-source. Read exactly how mode works, line by line, in Rust.

• View mode.rs on GitHub
• Learn how the runtime works
• Found a bug? Open an issue with a minimal reproduction.

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