Summary  
This chapter covers how to explore numerical data distributions by creating histograms and overlaying kernel density estimate curves using Seaborn’s `histplot` function in Python.

General domain of usage  
Data science exploratory analysis

Before you can draw meaningful conclusions from a dataset, you need to understand its structure and key characteristics. This process is called **data exploration**. It involves looking at your data from different angles, summarizing its main features, and visualizing important patterns. Data exploration helps you spot trends, outliers, and potential issues before performing deeper statistical analysis.

One of the most useful tools for exploring numerical data is the **histogram**. A histogram is a type of bar plot that shows how often different ranges of values appear in your dataset. Each bar represents a range of values (called a "bin"), and the height of the bar shows how many data points fall into that range. Histograms make it easy to see the distribution, center, and spread of your data at a glance.

In Python, you can quickly create histograms using the `histplot` function from the **seaborn** library. The `histplot` function takes your data and displays its distribution as a histogram. You can also add a **kernel density estimate** (KDE) curve to the plot, which gives a smooth approximation of the data’s distribution. This helps you better understand the underlying patterns in your data.

You will use the `histplot` function to visualize the distribution of penguin body masses in the upcoming tasks. This will help you explore the dataset and prepare for further statistical analysis.

import unittest
import pandas as pd
import seaborn as sns
import matplotlib.pyplot as plt

def _dynamic_test(test_case, condition, success_msg, failure_msg):
    if condition:
        test_case._testMethodName = success_msg
        test_case.assertTrue(True, success_msg)
    else:
        test_case._testMethodName = failure_msg
        test_case.fail(failure_msg)


class TestDataReading(unittest.TestCase):
    def test_data_loaded(self):
        import user_code

        expected_data = pd.read_csv(
            'https://codefinity-content-media.s3.eu-west-1.amazonaws.com/a849660e-ddfa-4033-80a6-94a1b7772e23/section_1/confidence.csv',
            index_col=0
        )

        condition = (
            isinstance(user_code.data, pd.DataFrame)
            and user_code.data.shape == expected_data.shape
        )

        _dynamic_test(
            self,
            condition,
            "The CSV file is correctly read into the 'data' variable.",
            "The CSV file is not read correctly into the 'data' variable."
        )


class TestPlot(unittest.TestCase):
    def test_histplot(self):
        import user_code

        # ÐÐµÑÐµÐ²ÑÑÑÑÐ¼Ð¾, ÑÐ¸ ÑÑÐ²Ð¾ÑÐµÐ½Ð¾ Ð³ÑÐ°ÑÑÐº Ð· seaborn.histplot
        plot_obj = user_code.plot

        condition = (
            hasattr(plot_obj, "get_xlabel")
            and plot_obj.get_xlabel() == "The Mass"
            and plot_obj.get_ylabel() == "The Quantity"
        )

        _dynamic_test(
            self,
            condition,
            "The histplot is created with correct parameters.",
            "The histplot parameters are incorrect."
        )


if __name__ == "__main__":
    unittest.main()


test_code.py

Build a strong foundation in statistics using Python. Learn essential statistical concepts and apply them through NumPy and pandas. Move from basic measures like mean and variance to hypothesis testing, confidence intervals, and data-driven insights with hands-on practice.

Discover core statistical principles, including data types, measures of central tendency, and key differences between samples and populations.

Learn to calculate and interpret mean, median, and mode using Python. Practice these operations with pandas to analyze real datasets.

Understand how variance and standard deviation measure data spread. Learn to compute both manually and using Python tools.

Explore how covariance and correlation describe relationships between variables. Practice calculating and comparing both metrics in Python.

Master confidence intervals to estimate population parameters. Use NumPy, pandas, and visualization libraries to calculate and interpret intervals with real data.

Learn the fundamentals of hypothesis testing and the t-test. Understand how to design, perform, and interpret tests using Python to support data-driven decisions.

Explore the Data Set

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