NumPy — Arrays

Create arrays

import numpy as np

# From list
arr = np.array([1, 2, 3, 4, 5])
print(arr)

# 2D array
arr_2d = np.array([[1, 2, 3], [4, 5, 6]])
print(arr_2d)

# 3D array
arr_3d = np.array([[[1, 2], [3, 4]], [[5, 6], [7, 8]]])

Data types

# Specify dtype
arr = np.array([1, 2, 3], dtype=np.float32)
print(arr.dtype)

# Convert types
arr_int = arr.astype(np.int32)

Array from function

# Using fromfunction
def my_func(i, j):
    return i + j

arr = np.fromfunction(my_func, (3, 3))
print(arr)

Empty arrays

# Empty (uninitialized)
empty = np.empty((3, 3))

# Zeros
zeros = np.zeros((3, 3))

# Ones
ones = np.ones((3, 3))

# Full
full = np.full((3, 3), 7)

Mini Practice

1. Create 1D, 2D, 3D arrays
2. Specify data types
3. Create empty/zero/one arrays
4. Use fromfunction

Up Next

Continue with Array Creation - Different creation methods.