mean
mean(v[, region])
Compute the mean of whole array v
, or optionally along the dimensions in region
. Note: Julia does not ignore NaN
values in the computation. For applications requiring the handling of missing data, the DataArray
package is recommended.
Examples
julia> xsum = rand(5)
mean(xsum)
0.38190307541901564
julia> A = rand(3)
3element Array{Float64,1}:
0.443922
0.79404
0.959896
julia> mean(A)
0.6369315513562785

Compute the mean of a 1dimensional array:
julia> v = [1, 2, 3, 4, 5]; julia> mean(v) 3.0
This example calculates the mean of the array
v
, which is 3.0. 
Compute the mean along a specific dimension of a multidimensional array:
julia> A = [1 2 3; 4 5 6; 7 8 9]; julia> mean(A, dims = 1) 1×3 Array{Float64,2}: 4.0 5.0 6.0
Here, the
mean
function is used to calculate the mean along the first dimension (columns) of the 2dimensional arrayA
. The result is a 1x3 array with the means of each column.  Compute the mean along multiple dimensions:
julia> B = [1 2 3; 4 5 6; 7 8 9; 10 11 12]; julia> mean(B, dims = (1, 2)) 1element Array{Float64,1}: 6.5
In this example, the
mean
function calculates the mean along both dimensions of the 2dimensional arrayB
. The result is a 1element array with the overall mean of the array.
Common mistake example:
julia> v = []
julia> mean(v)
ERROR: MethodError: no method matching mean(::Array{Any,1})
Here, an empty array v
is provided to the mean
function, which results in a MethodError
because Julia cannot determine the appropriate method to use. Make sure to provide a nonempty array to calculate the mean accurately.
See Also
cummax, eigmax, findmax, hist, hist!, hist2d, hist2d!, histrange, indmax, maxabs, maxabs!, maximum!, mean, mean!, median, median!, minabs, minabs!, minimum!, minmax, quantile!, realmax, std, stdm,User Contributed Notes
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