在 Python 中使用掩码数组的每个元素与给定标量值进行 AND 运算
要将给定的标量值与掩码数组的每个元素进行 AND 运算,请在 Python NumPy 中使用 **ma.MaskedArray.__rand__()** 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有效,要么是布尔值的数组,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、傅里叶变换等等。它支持各种硬件和计算平台,并且可以很好地与分布式、GPU 和稀疏数组库配合使用。
步骤
首先,导入所需的库 -
import numpy as np import numpy.ma as ma
使用 numpy.array() 方法创建包含整数元素的数组 -
arr = np.array([[8, 6, 1, 4], [6, 3, 9, 5], [9, 8, 1, 3], [5, 4, 7, 5]]) 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, 0], [ 0, 0, 1, 0], [0, 0, 0, 1], [0, 1, 0, 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)
要将给定的标量值与掩码数组的每个元素进行 AND 运算,请使用 ma.MaskedArray.__rand__() 方法 -
print("
Resultant Array...
",maskArr.__rand__(val))
示例
import numpy as np import numpy.ma as ma # Create an array with int elements using the numpy.array() method arr = np.array([[8, 6, 1, 4], [6, 3, 9, 5], [9, 8, 1, 3], [5, 4, 7, 5]]) 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, 0], [ 0, 0, 1, 0], [0, 0, 0, 1], [0, 1, 0, 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 AND a given scalar value with every element of a masked array, # use the ma.MaskedArray.__rand__() method print("Resultant Array...",maskArr.__rand__(val))
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输出
Array... [[8 6 1 4] [6 3 9 5] [9 8 1 3] [5 4 7 5]] Array type... int64 Array Dimensions... 2 Our Masked Array [[-- -- 1 4] [6 3 -- 5] [9 8 1 --] [5 -- 7 5]] Our Masked Array type... int64 Our Masked Array Dimensions... 2 Our Masked Array Shape... (4, 4) Elements in the Masked Array... 16 The given value.. 7 Resultant Array... [[-- -- 1 4] [6 3 -- 5] [1 0 1 --] [5 -- 7 5]]
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