Errors and exceptions

Real data is messy, and one bad row shouldn't crash a nightly job. try and except let you catch an error and decide what to do about it.

python

raw_amounts = ["499", "1299", "N/A", "250"]

clean, bad = [], []

for raw in raw_amounts:

    try:

        clean.append(int(raw))

    except ValueError:

        bad.append(raw)

print(clean)

print(bad)

OUTPUT

[499, 1299, 250] ['N/A']

Error	Usually means
`ValueError`	Right type, bad value: `int("N/A")`
`KeyError`	A dict key is missing
`TypeError`	Wrong type: `"a" + 1`
`FileNotFoundError`	The file path doesn't exist

watch out Catch specific errors like except ValueError, not a bare except:. A bare except also hides real bugs, such as a typo in a variable name.