Normalized histograms in Matplotlib - Cheat Sheet & Quick Revision

Recall & Review

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What is a normalized histogram?

A normalized histogram shows the relative frequency of data in each bin, so the total area sums to 1. It helps compare distributions regardless of sample size.

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How do you create a normalized histogram in matplotlib?

Use the parameter density=True in plt.hist(). This scales the histogram so the area under the bars equals 1.

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Why use normalized histograms instead of counts?

Normalized histograms allow comparison of data sets with different sizes by showing proportions instead of raw counts.

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What does the density=True parameter do in plt.hist()?

It scales the histogram so the sum of the bar areas equals 1, turning counts into probability densities.

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How can you interpret the height of bars in a normalized histogram?

The height represents the probability density, meaning the relative likelihood of data falling into that bin.

What parameter makes a histogram normalized in matplotlib?

A scale=True

B normed=True

C normalized=True

D density=True

The correct parameter is density=True. The older normed is deprecated.

What does a normalized histogram show?

A Relative frequency with total area 1

B Raw counts of data points

C Cumulative counts

D Data sorted in ascending order

Normalized histograms show relative frequency so the total area sums to 1.

Why use normalized histograms?

A To sort data points

B To compare data sets of different sizes

C To show raw counts only

D To remove outliers

Normalization helps compare distributions regardless of sample size.

If a histogram is normalized, what does the sum of bar heights equal?

A 1

B Number of data points

C It depends on bin size

D 100

The sum of bar heights depends on the bin size. The sum of the areas (height × width) equals 1.

Which matplotlib function is used to create histograms?

A plt.hist()

B plt.plot()

C plt.scatter()

D plt.bar()

plt.hist() creates histograms.

Explain how to create and interpret a normalized histogram using matplotlib.

Think about how normalization changes the meaning of bar heights.

Describe why normalized histograms are helpful in data analysis.

Consider comparing two groups with different numbers of samples.