使用 NumPy 在 Python 中就地將掩碼陣列的每個元素除以標量值

要就地將掩碼陣列的每個元素除以標量值，請在 Python NumPy 中使用 **ma.MaskedArray.__itruediv__()** 方法。

掩碼陣列是標準 numpy.ndarray 和掩碼的組合。掩碼要麼是 nomask，表示關聯陣列的任何值均無效，要麼是布林陣列，用於確定關聯陣列的每個元素的值是否有效。

NumPy 提供了全面的數學函式、隨機數生成器、線性代數例程、傅立葉變換等。它支援各種硬體和計算平臺，並且與分散式、GPU 和稀疏陣列庫配合良好。

步驟

首先，匯入所需的庫 -

import numpy as np
import numpy.ma as ma

使用 numpy.array() 方法建立具有浮點元素的陣列 -

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)

獲取陣列的維度 -

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

建立一個掩碼陣列並將其中一些標記為無效 -

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)

獲取掩碼陣列的維度 -

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

獲取掩碼陣列的形狀 -

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

獲取掩碼陣列的元素數量 -

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

標量 -

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

要就地將掩碼陣列的每個元素除以標量值，請使用 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))

輸出

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]]

AmitDiwan

更新於: 2022年2月17日

202 次檢視

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