python中lambda的用法

def f(x):

return x * x

print(f(5))

out: 25

f = lambda x: x*x # 冒号左边为输入，右边是返回值，f是函数名

print(f(5))

out: 25

g = lambda x,y: x+y # 冒号左边为输入，右边是返回值，f是函数名

print(g(4,5))

out: 9

def get_four(my):

return my[2]

tuple_my = []

file = open("file.csv", "r")

for line in file:

Line = line.strip()

arr = line.split(",")

one = arr[1]

three = arr[3]

four = int(arr[4])

tuple_my.append( (one, three, four) )

tuple_my.sort(key=get_four)

for my in tuple_my:

print(my)

get_four = lambda my: my[2]

tuple_my = []

file = open("file.csv", "r")

for line in file:

Line = line.strip()

arr = line.split(",")

one = arr[1]

three = arr[3]

four = int(arr[4])

tuple_my.append( (one, three, four) )

tuple_my.sort(key=get_four)

for my in tuple_my:

print(my)

tuple_my = []

file = open("file.csv", "r")

for line in file:

Line = line.strip()

arr = line.split(",")

one = arr[1]

three = arr[3]

four = int(arr[4])

tuple_my.append( (one, three, four) )

tuple_my.sort(key=lambda my: my[2])

for my in tuple_my:

print(my)

def quadratic(a, b, c):

return lambda x: a*x*x*x + b*x*x + c*x

f = quadratic(3, -2, 4)

print(f(5))

345

def quadratic(a, b, c):

return lambda x: a*x*x*x + b*x*x + c*x

print(quadratic(3, -2, 4)(5))

345