使用 NumPy 在 Python 中就地将掩码数组的每个元素除以标量值

要就地将掩码数组的每个元素除以标量值，请在 Python NumPy 中使用 **ma.MaskedArray.__itruediv__()** 方法。

掩码数组是标准 numpy.ndarray 和掩码的组合。掩码要么是 nomask，表示关联数组的任何值均无效，要么是布尔数组，用于确定关联数组的每个元素的值是否有效。

NumPy 提供了全面的数学函数、随机数生成器、线性代数例程、傅里叶变换等。它支持各种硬件和计算平台，并且与分布式、GPU 和稀疏数组库配合良好。

步骤

首先，导入所需的库 -

import numpy as np
import numpy.ma as ma

使用 numpy.array() 方法创建具有浮点元素的数组 -

arr = np.array([[65.5, 68.3, 81.2], [93.7, 33.8, 39.5], [73.4, 88.3, 51.9], [62.2, 45.5, 67.9]])
print("Array...
", arr)
print("
Array type...
", arr.dtype)

获取数组的维度 -

print("
Array Dimensions...
",arr.ndim)

创建一个掩码数组并将其中一些标记为无效 -

maskArr = ma.masked_array(arr, mask =[[1, 1, 0], [ 1, 0, 0], [0, 1, 0], [0, 1, 0]])
print("
Our Masked Array
", maskArr)
print("
Our Masked Array type...
", maskArr.dtype)

获取掩码数组的维度 -

print("
Our Masked Array Dimensions...
",maskArr.ndim)

获取掩码数组的形状 -

print("
Our Masked Array Shape...
",maskArr.shape)

获取掩码数组的元素数量 -

print("
Elements in the Masked Array...
",maskArr.size)

标量 -

val = 7
print("
The given value...
",val)

要就地将掩码数组的每个元素除以标量值，请使用 ma.MaskedArray.__itruediv__() 方法 -

print("
Resultant Masked Array...
",maskArr.__itruediv__(val))

示例

import numpy as np
import numpy.ma as ma

# Create an array with float elements using the numpy.array() method
arr = np.array([[65.5, 68.3, 81.2], [93.7, 33.8, 39.5], [73.4,88.3, 51.9], [62.2, 45.5, 67.9]])
print("Array...
", arr)
print("
Array type...
", arr.dtype)

# Get the dimensions of the Array
print("
Array Dimensions...
",arr.ndim)

# Create a masked array and mask some of them as invalid
maskArr = ma.masked_array(arr, mask =[[1, 1, 0], [ 1, 0, 0], [0, 1, 0], [0, 1, 0]])
print("
Our Masked Array
", maskArr)
print("
Our Masked Array type...
", maskArr.dtype)

# Get the dimensions of the Masked Array
print("
Our Masked Array Dimensions...
",maskArr.ndim)

# Get the shape of the Masked Array
print("
Our Masked Array Shape...
",maskArr.shape)

# Get the number of elements of the Masked Array
print("
Elements in the Masked Array...
",maskArr.size)
# The scalar
val = 7
print("
The given value...
",val)

# To true divide each element of a masked Array by a scalar value in-place, use the ma.MaskedArray.__itruediv__() method
print("
Resultant Masked Array...
",maskArr.__itruediv__(val))

输出

Array...
[[65.5 68.3 81.2]
[93.7 33.8 39.5]
[73.4 88.3 51.9]
[62.2 45.5 67.9]]

Array type...
float64

Array Dimensions...
2

Our Masked Array
[[-- -- 81.2]
[-- 33.8 39.5]
[73.4 -- 51.9]
[62.2 -- 67.9]]

Our Masked Array type...
float64

Our Masked Array Dimensions...
2

Our Masked Array Shape...
(4, 3)

Elements in the Masked Array...
12

The given value...
7

Resultant Masked Array...
[[-- -- 11.6]
[-- 4.828571428571428 5.642857142857143]
[10.485714285714286 -- 7.414285714285714]
[8.885714285714286 -- 9.700000000000001]]

更新于: 2022年2月17日

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