返回 NumPy 中掩碼陣列的絕對值
要返回掩碼陣列的絕對值,請使用 **ma.MaskedArray.__abs__()** 方法。如果元素為負數,則 abs() 方法會將其取反並返回。掩碼陣列是標準 numpy.ndarray 和掩碼的組合。掩碼可以是 nomask(表示關聯陣列的沒有值無效)或布林陣列(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、傅立葉變換等等。它支援各種硬體和計算平臺,並且可以很好地與分散式、GPU 和稀疏陣列庫配合使用。
步驟
首先,匯入所需的庫:
import numpy as np import numpy.ma as ma
使用 numpy.array() 方法建立一個包含整型元素的陣列:
arr = np.array([[55, 85, -68, 84], [67, -33, -39, -53], [29, 88, -51, 37], [-56, -45, 67, 85]]) 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元素標記為無效:
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)
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個數:
print("
Elements in the Masked Array...
",maskArr.size)
要返回掩碼陣列的絕對值,請使用 ma.MaskedArray.__abs__() 方法。如果元素為負數,則 abs() 方法會將其取反並返回。如果元素為正數,則 abs() 方法會返回相同的值:
print("
Returning the absolute value of the elements of a masked array...
", maskArr.__abs__())
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([[55, 85, -68, 84], [67, -33, -39, -53], [29, 88, -51, 37], [-56, -45, 67, 85]]) 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) # To return the absolute value of a masked Array, use the ma.MaskedArray.__abs__() method # If the element is negative, the abs() method negates it and returns # If the element is positive, the abs() method returns the same value print("
Returning the absolute value of the elements of a masked array...
", maskArr.__abs__())
輸出
Array... [[ 55 85 -68 84] [ 67 -33 -39 -53] [ 29 88 -51 37] [-56 -45 67 85]] Array type... int64 Array Dimensions... 2 Our Masked Array [[-- -- -68 84] [67 -33 -- -53] [29 88 -51 --] [-56 -- 67 85]] Our Masked Array type... int64 Our Masked Array Dimensions... 2 Our Masked Array Shape... (4, 4) Elements in the Masked Array... 16 Returning the absolute value of the elements of a masked array... [[-- -- 68 84] [67 33 -- 53] [29 88 51 --] [56 -- 67 85]]
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