Coding Grandmaster · project 28 of 46 · premium, free for now

A histogram in text

Count how many students got each grade and print one line per grade in alphabetical order, like A | #### 4.

Learn

A frequency table counts how often each value occurs. Printing a bar of # symbols for each count turns the numbers into a picture you can read at a glance. Sorting the keys keeps the picture in order, and a bar can be made by multiplying a string: "#" * 4.

Your task

Count how many students got each grade and print one line per grade in alphabetical order, like A | #### 4.

Stretch challenge

Scale the bars so the longest bar is at most 20 characters.

← Quartiles and outliers Do two things move together? →

Python

Press Run to see what your program prints.

Keep going in Coding Grandmaster

Averages

Write mean(data), median(data) and mode(data). If several values tie for most common, mode returns the smallest of them. Print all three for the list.

Start →26

How spread out?

Write data_range(data), variance(data) and std_dev(data) (population versions, dividing by n). Print them for the data, rounding the standard deviation to 4 decimal places.

Start →27

Quartiles and outliers

Write quartiles(data) returning (q1, q2, q3) by the method above, and outliers(data) returning the sorted list of outliers by the 1.5 × IQR rule.

Start →29

Do two things move together?

Write correlation(xs, ys) that returns Pearson's r rounded to 4 decimal places. Print it for study hours against marks.

Start →30

Scaling and z-scores

Write min_max(values) and z_scores(values) (use the population standard deviation). Both return lists with each number rounded to 2 decimal places.

Start →

Practise the idea

🃏 Play Maths Memory Match

Flip cards to match each sum with its answer. Times tables, addition, fractions and percentages.

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FAQ

A histogram in text: common questions

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