Append values to the end of a masked array in Numpy

NumpyServer Side ProgrammingProgramming

To append values to the end of an array, use the ma.append() method in Python Numpy. The values are appended to a copy of the first parameter array. These values are appended to a copy of first parameter array. It must be of the correct shape. If axis is not specified, the second parameter array can be any shape and will be flattened before use. The function returns a copy of array1 with array2 appended to axis. The append does not occur in-place: a new array is allocated and filled. If axis is None, the result is a flattened array.

The axis is an axis along which v are appended. If axis is not given, both a and b are flattened before use.

Steps

At first, import the required library −

import numpy as np
import numpy.ma as ma

Create Array 1, a 3x3 array with int elements using the numpy.arange() method −

arr1 = np.arange(9).reshape((3,3))
print("Array1...
", arr1) print("
Array type...
", arr1.dtype)

Create a masked array1 −

arr1 = ma.array(arr1)

Mask Array1 −

maskArr1 = ma.masked_values(arr1, 5)

Display Masked Array 1 −

print("
Masked Array1...
",maskArr1)

Create Array 2, another 3x3 array with int elements using the numpy.arange() method −

arr2 = np.arange(9).reshape((3,3))
print("
Array2...
", arr2) print("
Array type...
", arr2.dtype)

Create masked array2 −

arr2 = ma.array(arr2)

Mask Array2 −

maskArr2 = ma.masked_values(arr2, 7)

Display Masked Array 2 −

print("
Masked Array2...
",maskArr2)

To append values to the end of an array, use the ma.append() method in Python Numpy −

print("
Result of append...
",ma.append(maskArr1, maskArr2))

Example

import numpy as np
import numpy.ma as ma

# Array 1
# Creating a 3x3 array with int elements using the numpy.arange() method
arr1 = np.arange(9).reshape((3,3))
print("Array1...
", arr1) print("
Array type...
", arr1.dtype) # Get the dimensions of the Array print("
Array Dimensions...
",arr1.ndim) # Get the shape of the Array print("
Our Array Shape...
",arr1.shape) # Get the number of elements of the Array print("
Elements in the Array...
",arr1.size) # Create a masked array arr1 = ma.array(arr1) # Mask Array1 maskArr1 = ma.masked_values(arr1, 5) # Display Masked Array 1 print("
Masked Array1...
",maskArr1) # Array 2 # Creating another 3x3 array with int elements using the numpy.arange() method arr2 = np.arange(9).reshape((3,3)) print("
Array2...
", arr2) print("
Array type...
", arr2.dtype) # Get the dimensions of the Array print("
Array Dimensions...
",arr2.ndim) # Get the shape of the Array print("
Our Array Shape...
",arr2.shape) # Get the number of elements of the Array print("
Elements in the Array...
",arr2.size) # Create a masked array arr2 = ma.array(arr2) # Mask Array2 maskArr2 = ma.masked_values(arr2, 7) # Display Masked Array 2 print("
Masked Array2...
",maskArr2) # To append values to the end of an array, use the ma.append() method in Python Numpy print("
Result of append...
",ma.append(maskArr1, maskArr2))

Output

Array1...
[[0 1 2]
[3 4 5]
[6 7 8]]

Array type...
int64

Array Dimensions...
2

Our Array Shape...
(3, 3)

Elements in the Array...
9
Masked Array1...
[[0 1 2]
[3 4 --]
[6 7 8]]

Array2...
[[0 1 2]
[3 4 5]
[6 7 8]]

Array type...
int64

Array Dimensions...
2

Our Array Shape...
(3, 3)

Elements in the Array...
9

Masked Array2...
[[0 1 2]
[3 4 5]
[6 -- 8]]

Result of append...
[0 1 2 3 4 -- 6 7 8 0 1 2 3 4 5 6 -- 8]
raja
Updated on 04-Feb-2022 11:48:34

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