NumPy concatenate()

concatenate() is a function in the NumPy library used to concatenate two or more arrays together along a given axis. It takes in a tuple of arrays as its first argument and a keyword argument axis which specifies the axis to concatenate along.

Syntax

numpy.concatenate((a1, a2, ...), axis=0, out=None)

Example

import numpy as np

a = np.array([[1, 2], [3, 4]])
b = np.array([[5, 6]])

np.concatenate((a,b), axis=0)

Output:

array([[1, 2],
       [3, 4],
       [5, 6]])

In this example, two arrays a and b are defined. The concatenate() function is called with axis=0, which concatenates the arrays along the rows. The output is a new array with the same number of columns as the original arrays and the number of rows equal to the sum of the number of rows in the original arrays.

Explanation

The concatenate() function in NumPy is used to join two or more arrays along a given axis. The axis along which the arrays are concatenated is specified using the axis keyword argument. By default, the axis is set to 0, which means that the arrays are joined along the rows.

In the example above, two arrays are defined, a and b, and the concatenate() function is called with axis=0, which adds the elements of b as a new row to the bottom of a. If axis=1 were used instead, then b would be added as a new column to the right of a.

Use

The concatenate() function is commonly used in data manipulation tasks to join multiple arrays into a single array. It can be used to concatenate arrays along any axis, which makes it a versatile tool for data manipulation.

Important Points

• The tuple containing the arrays to be concatenated must have the same shape along the specified axis.
• The axis argument must be an integer that is less than the number of dimensions in the arrays.
• By default, concatenate() joins the arrays along the first axis.
• The out argument can be used to specify an output array.

Summary

In summary, numpy.concatenate() is a versatile function used to concatenate two or more arrays together along a specified axis. It can be used to join arrays along any axis, making it a useful tool for data manipulation tasks. By default, concatenate() joins arrays along the first axis, but this can be changed using the axis argument.