NumPy

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Installation

pip install numpy

Basic Usage

Importing NumPy

import numpy as np

Creating Arrays

From a List

arr = np.array([1, 2, 3])

From a Tuple

arr = np.array((1, 2, 3))

Using Functions

# Create an array of zeros
zeros = np.zeros((2, 3))

# Create an array of ones
ones = np.ones((2, 3))

# Create an array with a range of values
range_array = np.arange(0, 10, 2)

# Create an array with linearly spaced values
linspace_array = np.linspace(0, 1, 5)

Array Attributes

Getting Shape and Size

arr.shape
arr.size

Getting Data Type

arr.dtype

Array Operations

Arithmetic Operations

# Element-wise addition
result = arr1 + arr2

# Element-wise subtraction
result = arr1 - arr2

# Element-wise multiplication
result = arr1 * arr2

# Element-wise division
result = arr1 / arr2

Universal Functions

# Square root
result = np.sqrt(arr)

# Exponential
result = np.exp(arr)

# Sine
result = np.sin(arr)

Indexing and Slicing

Accessing Elements

element = arr[0]

# 2D array
element = arr[0, 1]

Slicing Arrays

# 1D array
slice = arr[1:4]

# 2D array
slice = arr[0:2, 1:3]

Array Manipulation

Reshaping Arrays

reshaped = arr.reshape((3, 2))

Flattening Arrays

flattened = arr.flatten()

Transposing Arrays

transposed = arr.T

Statistical Operations

Basic Statistics

mean = arr.mean()
std_dev = arr.std()
sum = arr.sum()
min_value = arr.min()
max_value = arr.max()

Axis-wise Operations

# Sum along an axis
sum_axis = arr.sum(axis=0)

Example

Complete Example

import numpy as np

# Create an array
arr = np.array([[1, 2, 3], [4, 5, 6]])

# Print the array
print('Array:
', arr)

# Array attributes
print('Shape:', arr.shape)
print('Size:', arr.size)
print('Data type:', arr.dtype)

# Array operations
print('Sum of all elements:', arr.sum())
print('Mean of all elements:', arr.mean())
print('Standard deviation:', arr.std())

# Indexing and slicing
print('Element at (0, 1):', arr[0, 1])
print('First row:', arr[0, :])
print('Second column:', arr[:, 1])

# Reshape the array
reshaped = arr.reshape((3, 2))
print('Reshaped array:
', reshaped)

# Transpose the array
transposed = arr.T
print('Transposed array:
', transposed)