NumPy median()

import numpy as np

# create an array
array1 = np.array([0, 1, 2, 3, 4, 5, 6, 7])

# calculate the median of the array
median1 = np.median(array1)

print(median1)

# Output: 3.5

median() 语法

numpy.median() 方法的语法是

numpy.median(array, axis = None, out = None, overwrite_input = False, keepdims = <no value>)

median() 参数

numpy.median() 方法接受以下参数

• array - 包含需要计算均值的数字的数组 (可以是 array_like)
• axis (可选) - 计算均值的轴或轴 (int 或 tuple of int)
• out (可选) - 用于存放结果的输出数组（ndarray）
• override_input (可选) - 确定中间计算是否可以修改数组的 bool 值
• keepdims (可选) - 指定是否保留原始数组的形状（bool）

median() 返回值

numpy.median() 方法返回数组的均值。

示例 1：查找 ndArray 的均值

import numpy as np

# create an array
array1 = np.array([[[0, 1], 
                    [2, 3]],                     
                    [[4, 5], 
                    [6, 7]]])

# find the median of the entire array
median1 = np.median(array1)

# find the median across axis 0
median2 = np.median(array1, 0)

# find the median across axis 0 and 1
median3 = np.median(array1, (0, 1))

print('\nmedian of the entire array:', median1)
print('\nmedian across axis 0:\n', median2)
print('\nmedian across axis 0 and 1', median3)

输出

median of the entire array: 3.5

median across axis 0:
 [[2. 3.]
 [4. 5.]]

median across axis 0 and 1 [3. 4.]

示例 2：使用可选的 keepdims 参数

如果将 keepdims 设置为 True，则生成的均值数组与原始数组具有相同的维度数。

import numpy as np

array1 = np.array([[1, 2, 3],
                [4, 5, 6]])

# keepdims defaults to False
result1 = np.median(array1, axis = 0)

# pass keepdims as True
result2 = np.median(array1, axis = 0, keepdims = True)

print('Dimensions in original array:', array1.ndim)
print('Without keepdims:', result1, 'with dimensions', result1.ndim)
print('With keepdims:', result2, 'with dimensions', result2.ndim)

输出

Dimensions in original array: 2
Without keepdims: [2.5 3.5 4.5] with dimensions 1
With keepdims: [[2.5 3.5 4.5]] with dimensions 2

示例 3：使用可选的 out 参数

out 参数允许指定一个输出数组，结果将存储在该数组中。

import numpy as np

array1 = np.array([[1, 2, 3],
                [4, 5, 6]])

# create an output array
output = np.zeros(3)

# compute median and store the result in the output array
np.median(array1, out = output, axis = 0)

print('median:', output)

输出

median: [2.5 3.5 4.5]