导语：
本文主要介绍了关于python中lambda的用法的相关知识，包括python中lambda和map，以及用lambda实现表达式定义函数这些编程知识，希望对大家有参考作用。
对于一个函数，只有一个句子可以表达，那么可以用lambda表达式来表达，比如：
def f(x):
return x * x
print(f(5))out: 25可以写为：
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对于多个形式参数：
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: 9lambda用到比较多的地方是排序，如：
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)可以写为：
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)lambda也经常用在符合函数下，如：
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))345def quadratic(a, b, c):
return lambda x: a*x*x*x + b*x*x + c*x
print(quadratic(3, -2, 4)(5))345本文为原创文章，版权归知行编程网所有，欢迎分享本文，转载请保留出处！
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