Track 6 · Lesson 6 of 12

Dictionary patterns: count, group, invert

Loop over keys, values and items, and use dictionaries to count occurrences, group records, invert mappings and total by category.

You will be able to

• Loop over a dictionary's keys, values and items
• Count occurrences with the get(key, 0) + 1 pattern
• Group items into lists under a key and total values by category
• Invert a mapping and recognise what happens with duplicate values