Count with a dict

Read first Task 42

Loop once and add 1 per key — the standard counting pattern.

Definition and example

Count with a dict is the focus of this lesson. Loop once and add 1 per key — the standard counting pattern. The task asks you to apply that idea in a small example: Which pattern counts occurrences. Before you run the code, predict what should happen. Then Inspect the printed output and the values your program uses and compare it with your prediction. If the result differs, change one relevant line and run it again. Testing one change at a time makes the cause of a result easier to understand.

Python 1 automatic check Build something real

Code editor Ctrl + Enter runs

# TASK count-with-a-dict-02: Which pattern counts occurrences?
# STEPS: Read the explanation. Change one relevant line at a time, then run the code and compare the result with the check on the right.
counts = {}
for w in ['a','a','b']:
    counts[w] = counts.get(w,0)+1
# TODO: produce the required output for this task.

Run your code to see the output and the checks.

Your result

Submit your code to see results

Write your code in the middle column and press Run code.

Checks on this task:

The program output must match “2”.

The task and step-by-step instructions are written as comments at the top of the editor. Change one relevant line, run it, and compare the result with these checks.

Incorrect attempts before answer: 0 / 3

Track progress

0 passed of 56 tasks

Pass every check or use one of your available skips to open the next task.

← Previous

Next task (pass every check first)

Count with a dict

Count with a dict

Why this works