Concatenating

Why Concatenating?

Concatenating is an another powerful feature in NumPy that allows you to combine multiple arrays into a single array.

This example demonstrates how concatenation can be used to combine multiple arrays into a single array, and how to use the np.vstack() and np.hstack() functions to concatenate arrays vertically and horizontally, respectively.

import numpy as np

# Create two NumPy arrays with sales data
array1 = np.array([1, 2, 3])
array2 = np.array([4, 5, 6])

# Concatenate the two arrays
concatenated_array = np.concatenate((array1, array2))

print("Concatenated Array: ", concatenated_array)

# Output: [1 2 3 4 5 6]

# Create two NumPy arrays with sales data
array1 = np.array([[1, 2], [3, 4]])
array2 = np.array([[5, 6], [7, 8]])

# Concatenate the two arrays vertically
vertically_concatenated_array = np.vstack((array1, array2))

print("Vertically Concatenated Array: \n", vertically_concatenated_array)

# Output:
# [[1 2]
#  [3 4]
#  [5 6]
#  [7 8]]

# Create two NumPy arrays with sales data
array1 = np.array([[1, 2], [3, 4]])
array2 = np.array([[5, 6], [7, 8]])

# Concatenate the two arrays horizontally
horizontally_concatenated_array = np.hstack((array1, array2))

print("Horizontally Concatenated Array: \n", horizontally_concatenated_array)

# Output:
# [[1 2 5 6]
#  [3 4 7 8]]

A real-world example:

Suppose we have two datasets of sales data for a company, one for the first half of the year and one for the second half of the year. We can use concatenation to combine these two datasets into a single array.

import numpy as np

# Create two NumPy arrays with sales data
first_half_sales = np.array([
    [100, 200, 300],  # January
    [120, 250, 320],  # February
    [150, 300, 350],  # March
    [180, 350, 380],  # April
    [200, 400, 420],  # May
    [220, 450, 450]   # June
])

second_half_sales = np.array([
    [250, 500, 550],  # July
    [280, 550, 580],  # August
    [300, 600, 650],  # September
    [320, 650, 680],  # October
    [350, 700, 750],  # November
    [380, 750, 780]   # December
])

# Concatenate the two arrays
annual_sales = np.concatenate((first_half_sales, second_half_sales))

print("Annual Sales: \n", annual_sales)

In this example, we create two NumPy arrays first_half_sales and second_half_sales with sales data for the first and second half of the year, respectively. We then use the np.concatenate() function to combine these two arrays into a single array annual_sales.

key concepts

Here are some key concepts to keep in mind when using concatenation:

• np.concatenate((array1, array2, ...)): This syntax is used to concatenate multiple arrays into a single array.
• np.vstack((array1, array2, ...)): This syntax is used to concatenate multiple arrays vertically (i.e., along the rows).
• np.hstack((array1, array2, ...)): This syntax is used to concatenate multiple arrays horizontally (i.e., along the columns).