Python error explained
KeyError: what it means and how to fix it
That key is not in the dictionary.
The message
KeyError: 'Ava'What it means
Square brackets on a dictionary demand that the key exists. If it does not, Python raises a KeyError naming the missing key. Keys are case sensitive too.
Common causes
- A typo or different capitals in the key
- Counting with counts[word] += 1 before the word has been added
- Expecting data that is not there
Example that raises it
votes = ["Ava", "Ben", "Ava", "Cal", "Ava"]
counts = {}
for name in votes:
counts[name] += 1
print(counts)
The fix
votes = ["Ava", "Ben", "Ava", "Cal", "Ava"]
counts = {}
for name in votes:
counts[name] = counts.get(name, 0) + 1
print(counts)
Tip: dict.get(key, default) returns the default instead of crashing, and "key in my_dict" lets you check first.
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