Question

循环遍历一系列数字并跳过一个值的pythonic方法是什么？例如，范围从0到100，我想跳过50。

编辑：这是我正在使用的代码

for i in range(0, len(list)):
    x= listRow(list, i)
    for j in range (#0 to len(list) not including x#)
        ...

Answer 1

您可以使用以下任何一种：

# Create a range that does not contain 50
for i in [x for x in xrange(100) if x != 50]:
    print i

# Create 2 ranges [0,49] and [51, 100] (Python 2)
for i in range(50) + range(51, 100):
    print i

# Create a iterator and skip 50
xr = iter(xrange(100))
for i in xr:
    print i
    if i == 49:
        next(xr)

# Simply continue in the loop if the number is 50
for i in range(100):
    if i == 50:
        continue
    print i

Answer 2

for i in range(100):
    if i == 50:
        continue
    dosomething

Answer 3

这取决于你想做什么。例如，你可以在你的理解中坚持这样的条件：

# get the squares of each number from 1 to 9, excluding 2
myList = [i**2 for i in range(10) if i != 2]
print(myList)

# --> [0, 1, 9, 16, 25, 36, 49, 64, 81]

Answer 4

除了Python 2方法外，这里还有Python 3的等效方法。

# Create a range that does not contain 50
for i in [x for x in range(100) if x != 50]:
    print(i)

# Create 2 ranges [0,49] and [51, 100]
from itertools import chain
concatenated = chain(range(50), range(51, 100))
for i in concatenated:
    print(i)

# Create a iterator and skip 50
xr = iter(range(100))
for i in xr:
    print(i)
    if i == 49:
        next(xr)

# Simply continue in the loop if the number is 50
for i in range(100):
    if i == 50:
        continue
    print(i)

范围是Python 2中的列表和Python 3中的迭代器。

Answer 5

比较每个数字很浪费时间，不必要地导致线性复杂性。话虽如此，这种方法避免了任何不平等检查：

import itertools

m, n = 5, 10
for i in itertools.chain(range(m), range(m + 1, n)):
    print(i)  # skips m = 5

顺便说一句，即使它可以工作，您也不想使用(*range(m), *range(m + 1, n))，因为它会将可迭代对象扩展为元组，并且内存效率低下。

信用：由njzk2发表评论，洛克提供答案

Answer 6

这对我有用；

示例：

x = ['apple', 'orange', 'grape', 'lion', 'banana', 'watermelon', 'onion', 'cat',]

for xr in x:
    if xr in 'onion':
        print('onion is a vegetable')
        continue
    if (xr not in 'lion' and xr not in 'cat'):
        print(xr, 'is a fruit')

输出 -->

apple is a fruit
orange is a fruit
grape is a fruit
banana is a fruit
watermelon is a fruit
onion is a vegetable

Answer 7

你可以做什么，在你想要远离50的循环中放置一个if语句。 e.g。

for i in range(0, len(list)):
    if i != 50:
        x= listRow(list, i)
        for j in range (#0 to len(list) not including x#)

跳过python中range函数中的值

8 个答案: