numpy.var(arr, axis = None) : Compute the variance of the given data (array elements) along the specified axis(if any).
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Example :
x = 1 1 1 1 1
Standard Deviation = 0 . Variance = 0
y = 9, 2, 5, 4, 12, 7, 8, 11, 9, 3, 7, 4, 12, 5, 4, 10, 9, 6, 9, 4
Step 1 : Mean of distribution 4 = 7
Step 2 : Summation of (x - x.mean())**2 = 178
Step 3 : Finding Mean = 178 /20 = 8.9
This Result is Variance.
Parameters :
arr : [array_like] input array.
axis : [int or tuples of int] axis along which we want to calculate the variance. Otherwise, it will consider arr to be flattened (works on all the axis). axis = 0 means variance along the column and axis = 1 means variance along the row.
out : [ndarray, optional] Different array in which we want to place the result. The array must have the same dimensions as expected output.
dtype : [data-type, optional] Type we desire while computing variance.
Results : Variance of the array (a scalar value if axis is none) or array with variance values along specified axis.
Code #1:
Output :
arr : [20, 2, 7, 1, 34]
var of arr : 158.16
var of arr : 158.16
var of arr : 158.16
Code #2:
Output :
var of arr, axis = None : 236.14000000000004
var of arr, axis = 0 : [ 57.1875 312.75 345.6875 9.25 0. ]
var of arr, axis = 1 : [ 0. 77.04 421.84 269.04]
