For example, you can take the absolute value of each element:
list(map(abs, (1, -1, 2, -2, 3, -3))) # the call to `list` is unnecessary in 2.x
# Out: [1, 1, 2, 2, 3, 3]
Anonymous function also support for mapping a list:
map(lambda x:x*2, [1, 2, 3, 4, 5])
# Out: [2, 4, 6, 8, 10]
or converting decimal values to percentages:
def to_percent(num):
return num * 100
list(map(to_percent, [0.95, 0.75, 1.01, 0.1]))
# Out: [95.0, 75.0, 101.0, 10.0]
or converting dollars to euros (given an exchange rate):
from functools import partial
from operator import mul
rate = 0.9 # fictitious exchange rate, 1 dollar = 0.9 euros
dollars = {'under_my_bed': 1000,
'jeans': 45,
'bank': 5000}
sum(map(partial(mul, rate), dollars.values()))
# Out: 5440.5
functools.partial
is a convenient way to fix parameters of functions so that they can be used with map
instead of using lambda
or creating customized functions.