NumPy Create array filled with all ones (original) (raw)
Last Updated : 24 Jan, 2025
To create an **array filled with all ones, given the shape and type of array, we can use **numpy.ones() method of NumPy library in Python.
Python `
import numpy as np
array = np.ones(5) print(array)
`
**Output:
[1. 1. 1. 1. 1.]
2D Array of Ones
We can also create a 2D array (matrix) filled with ones by passing a tuple to the shape parameter.
Python `
import numpy as np
Create a 2D array of ones (3 rows, 4 columns)
ones_array_2d = np.ones((3, 4)) print(ones_array_2d)
`
Output
[[1. 1. 1. 1.] [1. 1. 1. 1.] [1. 1. 1. 1.]]
Array with a Specific Data Type
We can specify the data type of the array using the dtype parameter.
Python `
import numpy as np
Create an integer array of ones with 4 elements
ones_int_array = np.ones(4, dtype=int) print(ones_int_array)
`
**Explanation:
- By specifying dtype=int, we ensure that the array is of integer type instead of the **default float64.
Multi-Dimensional Array of Ones
We can also create a higher-dimensional array (3D or more) by passing a tuple representing the shape.
Python `
import numpy as np
Create a 3D array of ones with shape (2, 3, 4)
ones_array_3d = np.ones((2, 3, 4)) print(ones_array_3d)
`
Output
[[[1. 1. 1. 1.] [1. 1. 1. 1.] [1. 1. 1. 1.]]
[[1. 1. 1. 1.] [1. 1. 1. 1.] [1. 1. 1. 1.]]]