list comprehension 后面可以有多个for loops,每个for后面可以有if [(x, y, x * y)for x in(0,1,2,3)for y in(0,1,2,3)if x < y]等同于: for x in (0,1,2,3): for y in (0,1,2,3): if x < y: print (x, y, x*y) It also supports both “if" statements and referencing the outer i…
Comprehension Extensions 关于解析式的相关语言扩展. List and Comprehension Extensions 24 Days of GHC Extensions: List Comprehensions ParallelListComp Prelude> [(w,x,y,z) | ((w,x),(y,z)) <- zip [(w,x) | w <- [1..3], x <- [2..4]] [(y,z) | y <- [3..5], z &…
x for x in x 链表推导式 [list comprehension]链表推导式提供了一个创建链表的简单途径,无需使用 map(), filter() 以及 lambda.返回链表的定义通常要比创建这些链表更清晰.每一个链表推导式包括在一个for语句之后的表达式,零或多个for或if语句.返回值是由for或if子句之后的表达式得到的元素组成的链表.如果想要得到一个元组,必须要加上括号.>>> freshfruit = [' banana', ' loganberry ', 'pa…
List comprehensions(列表推导式) are better when you want to iterate over something multiple times. However, it's also worth noting that you should use a list if you want to use any of the list methods. Basically, use a generator expression(生成器推导式/生成器表达式)…
如果想通过操作和处理一个序列(或其他的可迭代对象)来创建一个新的列表时可以使用列表解析(List comprehensions)和生成表达式(generator expression) (1)list comprehension [expr for iter_var in iterable ] or [expr for iter_ in iterable if cond_expr] l1=[1,2,3,4,5] [x+1 for x in l1] [2, 3, 4, 5, 6] [x-1 for…