Comprehensions

A comprehension builds a new list in one line. Read it as: give me this, for each item, if a condition holds.

python

amounts = [499, 1299, 250, 80]

big = [a for a in amounts if a > 300]

with_gst = [round(a * 1.18) for a in amounts]

print(big)

print(with_gst)

OUTPUT

[499, 1299] [589, 1533, 295, 94]

The same idea works for dicts: {k: v.upper() for k, v in names.items()}.

watch out If a comprehension needs several conditions or won't fit on one line, write a normal loop. Code is read far more often than it's written.