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How to Plot A Histogram In Matplotlib In Python?

5 minutes read

To plot a histogram in matplotlib in Python, you can use the 'hist' function from the matplotlib.pyplot library. This function takes in the data that you want to plot as well as other optional parameters such as the number of bins and the colors of the bars. You can also customize the appearance of the histogram by adding labels, titles, and changing the color scheme. Finally, you can display the histogram by calling the 'show' function from the matplotlib.pyplot library.


How to plot a normalized histogram in matplotlib?

To plot a normalized histogram in matplotlib, you can use the hist function along with the density=True parameter. Here is an example:

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import matplotlib.pyplot as plt
import numpy as np

# generate some random data
data = np.random.normal(0, 1, 1000)

# plot normalized histogram
plt.hist(data, bins=30, density=True)
plt.xlabel('Value')
plt.ylabel('Frequency')
plt.title('Normalized Histogram')
plt.show()


By setting density=True, the histogram will be normalized so that the total area under the histogram will sum to 1. This allows you to compare the shape of different distributions without being influenced by differences in sample size.


How to create a 3D histogram in matplotlib?

To create a 3D histogram in Matplotlib, you can use the hist3d function from the mpl_toolkits.mplot3d module. Here is an example code snippet to create a 3D histogram:

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import matplotlib.pyplot as plt
import numpy as np
from mpl_toolkits.mplot3d import Axes3D

# Generate some random data
data = np.random.randn(1000, 3)

fig = plt.figure()
ax = fig.add_subplot(111, projection='3d')

# Create a 3D histogram
hist, edges = np.histogramdd(data, bins=10, range=[[-3, 3], [-3, 3], [-3, 3]])

# Get the centers of the bins
x_centers = (edges[0][1:] + edges[0][:-1]) / 2
y_centers = (edges[1][1:] + edges[1][:-1]) / 2
z_centers = (edges[2][1:] + edges[2][:-1]) / 2

# Plot the 3D histogram using bar3d function
x, y, z = np.meshgrid(x_centers, y_centers, z_centers, indexing='ij')
ax.bar3d(x.ravel(), y.ravel(), z.ravel(), 0.5, 0.5, hist.ravel(), shade=True)

# Set labels and title
ax.set_xlabel('X axis')
ax.set_ylabel('Y axis')
ax.set_zlabel('Z axis')
ax.set_title('3D Histogram')

plt.show()


This code snippet generates random data points in a 3D space and creates a 3D histogram using the histogramdd function. The bar3d function is then used to plot the histogram in 3D space. You can customize the number of bins, range, and the width of the bars in the histogram to suit your needs.


How to add a title to a histogram plot in matplotlib?

To add a title to a histogram plot in matplotlib, you can use the plt.title() function before displaying the plot with plt.show(). Here is an example code snippet to add a title to a histogram plot:

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import matplotlib.pyplot as plt

# Create some data for the histogram
data = [1, 2, 3, 4, 5, 5, 6, 6, 6, 7, 8, 8, 8, 8]

# Create a histogram plot
plt.hist(data, bins=10, color='skyblue', edgecolor='black')

# Add a title to the plot
plt.title('Histogram Plot')

# Display the plot
plt.show()


In this code snippet, the title 'Histogram Plot' is added to the histogram plot using plt.title('Histogram Plot'). You can customize the title text and appearance by passing additional arguments to the plt.title() function.


What is the relationship between histograms and probability distributions?

A histogram is a graphical representation of the frequency distribution of a set of data, where the data is divided into intervals or bins and the frequency of data points falling into each bin is represented by the height of the bars.


Probability distributions, on the other hand, describe how the probabilities of various outcomes are distributed for a random variable. Probability distributions can take various forms, such as the normal distribution, uniform distribution, exponential distribution, etc.


Histograms can be used to visually represent the shape of a probability distribution. By constructing a histogram of a dataset that follows a certain distribution, one can see the patterns and characteristics of that distribution. For example, a normal distribution would typically be represented by a symmetric bell-shaped histogram.


In summary, histograms provide a visual representation of the frequency distribution of data, while probability distributions describe the likelihood of different outcomes. Histograms can be used to better understand and visualize probability distributions.


How to display the frequency of each bin in a histogram plot in matplotlib?

You can display the frequency of each bin in a histogram plot in matplotlib by using the plt.text() function to add text labels above each bar in the histogram. Here's an example code snippet that demonstrates how to do this:

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import matplotlib.pyplot as plt
import numpy as np

# Generate some random data
data = np.random.randint(0, 10, size=100)

# Create a histogram plot
plt.hist(data, bins=10, edgecolor='black')

# Get the frequency of each bin
counts, bins, _ = plt.hist(data, bins=10)

# Add text labels above each bar
for i in range(len(counts)):
    plt.text(bins[i], counts[i], str(int(counts[i])), ha='center', va='bottom')

plt.show()


In this code snippet, we first generate some random data and create a histogram plot using plt.hist(). Then, we use the plt.hist() function again to get the frequency counts for each bin. Finally, we loop through the counts and bins to add text labels above each bar in the histogram using the plt.text() function.


How to overlay a normal distribution on a histogram plot in matplotlib?

To overlay a normal distribution on a histogram plot in Matplotlib, you can follow these steps:

  1. Generate random data following a normal distribution by using the numpy library. For example, you can generate 1000 data points with a mean of 0 and a standard deviation of 1:
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import numpy as np

data = np.random.normal(0, 1, 1000)


  1. Create a histogram plot using matplotlib.pyplot.hist() function. Make sure to specify the number of bins for a better representation of the data:
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import matplotlib.pyplot as plt

plt.hist(data, bins=30, density=True, alpha=0.6, color='g')


  1. Overlay a normal distribution on the histogram plot by using the scipy.stats.norm module to create a normal distribution curve. You can compute the mean and standard deviation of the data to fit the curve:
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import scipy.stats as stats

mu, sigma = np.mean(data), np.std(data)
x = np.linspace(mu - 3*sigma, mu + 3*sigma, 100)
plt.plot(x, stats.norm.pdf(x, mu, sigma), color='r')


  1. Finally, display the histogram plot with the overlaid normal distribution:
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plt.show()


By following these steps, you should be able to create a histogram plot with a normal distribution overlay in Matplotlib.

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