在 Numpy 中計算軸 1 上的掩蓋元素數量


要計算軸 1 上的掩蓋元素數量,可以使用ma.MaskedArray.count_masked() 方法。軸使用“axis”引數進行設定。該方法返回掩蓋元素的總數(axis=None)或給出軸的每個切片的掩蓋元素數量。

axis 引數是要計算的軸。如果為 None(預設值),則使用陣列的展平版本。

步驟

首先,匯入所需的庫 -

import numpy as np
import numpy.ma as ma

使用 numpy.arange() 方法建立一個含有 int 元素的 4x4 陣列 -

arr = np.arange(16).reshape((4,4))
print("Array...
", arr) print("
Array type...
", arr.dtype)

獲取陣列的維度 -

print("
Array Dimensions...
",arr.ndim) print("
Our Array type...
", arr.dtype)

獲取陣列的形狀 -

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

獲取陣列的元素數量 -

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

建立掩蓋陣列 -

arr = ma.array(arr)
arr[0, 1] = ma.masked
arr[1, 1] = ma.masked
arr[2, 1] = ma.masked
arr[2, 2] = ma.masked
arr[3, 0] = ma.masked
arr[3, 2] = ma.masked
arr[3, 3] = ma.masked

若要計算特定軸上的掩蓋元素數量,請使用 ma.MaskedArray.count_masked() 方法。軸使用“axis”引數進行設定 -

print("
Result (number of masked elements)...
",ma.count_masked(arr, axis = 1))

示例

import numpy as np
import numpy.ma as ma

# Creating a 4x4 array with int elements using the numpy.arange() method
arr = np.arange(16).reshape((4,4))
print("Array...
", arr) print("
Array type...
", arr.dtype) # Get the dimensions of the Array print("
Array Dimensions...
",arr.ndim) print("
Our Array type...
", arr.dtype) # Get the shape of the Array print("
Our Masked Array Shape...
",arr.shape) # Get the number of elements of the Array print("
Elements in the Masked Array...
",arr.size) # Create a masked array arr = ma.array(arr) arr[0, 1] = ma.masked arr[1, 1] = ma.masked arr[2, 1] = ma.masked arr[2, 2] = ma.masked arr[3, 0] = ma.masked arr[3, 2] = ma.masked arr[3, 3] = ma.masked # To count the number of masked elements along specific axis, use the ma.MaskedArray.count_masked() method # The axis is set using the "axis" parameter print("
Result (number of masked elements)...
",ma.count_masked(arr, axis = 1))

輸出

Array...
[[ 0 1 2 3]
[ 4 5 6 7]
[ 8 9 10 11]
[12 13 14 15]]

Array type...
int64

Array Dimensions...
2

Our Array type...
int64

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

Elements in the Masked Array...
16

Result (number of masked elements)...
[1 1 2 3]

更新於:2022-02-21

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