Python: Lambda

Lambda is used to define a function. Aka anonymous function.

💡 TIP: python lambda body must be in a single line. Usually for simple functions. If you need more than one line, use def . 〔see Python: Function〕

# lambda with one arg
# a function that adds 1
print((lambda x: x + 1)(3))
# 4

# lambda with two args
# a function that adds two numbers
print((lambda x, y: x + y)(3, 4))
# 7

# give lambda a name
ff = lambda x: x + 1
print(ff(3))
# 4

# add 2 numbers
ff = lambda x, y: x + y
print(ff(3, 4))
# 7

lambda is often used with map or filter.

xx = [1, 2, 3, 4, 5]

# keep just even numbers
yy = filter(lambda x: x % 2 == 0, xx)

print(list(yy))
# [2, 4]