Return Masked Array Data as String in NumPy

To return the array data as a string containing the raw bytes in the array, use the ma.MaskedArray.tobytes() method in Numpy.

The fill_value parameter is the value used to fill in the masked values. Default is None, in which case MaskedArray.fill_value is used.

The order parameter is the Order of the data item in the copy. Default is ‘C’.

• ‘C’ - C order (row major).

• ‘F’ - Fortran order (column major).

• ‘A’ - Any, current order of array.

• None - Same as ‘A’.

Steps

At first, import the required library −

import numpy as np
import numpy.ma as ma

Create an array with int elements using the numpy.array() method −

arr = np.array([[49, 85, 45], [67, 33, 59]])
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 =[[0, 0, 1], [ 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)

Return the array data as a string containing the raw bytes in the array, use the ma.MaskedArray.tobytes() method in Numpy. The Order of the data item in the copy is set using the "order" parameter. The 'F' order is for Fortran order i.e. column major −

print("
Result...
",maskArr.tobytes(fill_value = 9999, order = 'F'))

Example

# Python ma.MaskedArray - Return the array data as a string containing the raw bytes in the array and
# set the column major order of the resultant data

import numpy as np
import numpy.ma as ma

# Create an array with int elements using the numpy.array() method
arr = np.array([[49, 85, 45], [67, 33, 59]])
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 =[[0, 0, 1], [ 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)

# To return the array data as a string containing the raw bytes in the array, use the ma.MaskedArray.tobytes() method in Numpy
# The "fill_value" parameter is the value used to fill in the masked values.
# Default is None, in which case MaskedArray.fill_value is used.
# The Order of the data item in the copy is set using the "order" parameter
# The 'F' order is for Fortran order i.e. column major
print("
Result...
",maskArr.tobytes(fill_value = 9999, order = 'F'))

Output

Array...
[[49 85 45]
[67 33 59]]

Array type...
int64

Array Dimensions...
2

Our Masked Array
[[49 85 --]
[67 -- 59]]

Our Masked Array type...
int64

Our Masked Array Dimensions...
2

Our Masked Array Shape...
(2, 3)

Elements in the Masked Array...
6

Result...
b"1\x00\x00\x00\x00\x00\x00\x00C\x00\x00\x00\x00\x00\x00\x00U\x00\x00\x00\x00\x00\x00\x00\x0f'\x00\x00\x00\x00\x00\x00\x0f'\x00\x00\x00\x00\x00\x00;\x00\x00\x00\x00\x00\x00\x00"