建站
咨詢
售后
建站咨詢
新聞中心
這里有您想知道的互聯(lián)網(wǎng)營銷解決方案
創(chuàng)新互聯(lián)Python教程：python中l(wèi)ambda的用法
對于一個函數(shù)，只有一句話表示，那么就可以用lambda表達(dá)式表示，如：
def f(x): return x * x print(f(5))
out: 25
可以寫為：
f = lambda x: x*x # 冒號左邊為輸入，右邊是返回值，f是函數(shù)名 print(f(5))
out: 25
對于多個形式參數(shù)：
g = lambda x,y: x+y # 冒號左邊為輸入，右邊是返回值，f是函數(shù)名 print(g(4,5))
out: 9
lambda用到比較多的地方是排序，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)可以寫為：
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也經(jīng)常用在符合函數(shù)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))
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
分享文章：創(chuàng)新互聯(lián)Python教程：python中l(wèi)ambda的用法
本文來源：http://www.5511xx.com/article/dhcejpj.html
