Python 中的 numpy.sum()
numpy.sum(arr, axis, dtype, out)
: 该函数返回指定轴上数组元素的总和。
参数: arr : 输入阵。 轴:轴,我们要沿着该轴计算和值。否则,它将考虑将 arr 展平(在所有轴上工作)。axis = 0 表示沿列工作,axis = 1 表示沿行工作。 出:不同的数组中我们要放置的结果。数组必须具有与预期输出相同的维度。默认值为无。 初始值:【标量,可选】总和的起始值。
返回:数组元素的总和(如果轴为无,则为标量值)或沿指定轴具有总和值的数组。
代码#1:
# Python Program illustrating
# numpy.sum() method
import numpy as np
# 1D array
arr = [20, 2, .2, 10, 4]
print("\nSum of arr : ", np.sum(arr))
print("Sum of arr(uint8) : ", np.sum(arr, dtype = np.uint8))
print("Sum of arr(float32) : ", np.sum(arr, dtype = np.float32))
print ("\nIs np.sum(arr).dtype == np.uint : ",
np.sum(arr).dtype == np.uint)
print ("Is np.sum(arr).dtype == np.float : ",
np.sum(arr).dtype == np.float)
输出:
Sum of arr : 36.2
Sum of arr(uint8) : 36
Sum of arr(float32) : 36.2
Is np.sum(arr).dtype == np.uint : False
Is np.sum(arr).dtype == np.uint : True
代码#2:
# Python Program illustrating
# numpy.sum() method
import numpy as np
# 2D array
arr = [[14, 17, 12, 33, 44],
[15, 6, 27, 8, 19],
[23, 2, 54, 1, 4,]]
print("\nSum of arr : ", np.sum(arr))
print("Sum of arr(uint8) : ", np.sum(arr, dtype = np.uint8))
print("Sum of arr(float32) : ", np.sum(arr, dtype = np.float32))
print ("\nIs np.sum(arr).dtype == np.uint : ",
np.sum(arr).dtype == np.uint)
print ("Is np.sum(arr).dtype == np.uint : ",
np.sum(arr).dtype == np.float)
输出:
Sum of arr : 279
Sum of arr(uint8) : 23
Sum of arr(float32) : 279.0
Is np.sum(arr).dtype == np.uint : False
Is np.sum(arr).dtype == np.uint : False
代码#3:
# Python Program illustrating
# numpy.sum() method
import numpy as np
# 2D array
arr = [[14, 17, 12, 33, 44],
[15, 6, 27, 8, 19],
[23, 2, 54, 1, 4,]]
print("\nSum of arr : ", np.sum(arr))
print("Sum of arr(axis = 0) : ", np.sum(arr, axis = 0))
print("Sum of arr(axis = 1) : ", np.sum(arr, axis = 1))
print("\nSum of arr (keepdimension is True): \n",
np.sum(arr, axis = 1, keepdims = True))
输出:
Sum of arr : 279
Sum of arr(axis = 0) : [52 25 93 42 67]
Sum of arr(axis = 1) : [120 75 84]
Sum of arr (keepdimension is True):
[[120]
[ 75]
[ 84]]