Question

我有一个巨大的文本文件，包含＆＃34; blocks＆＃34;像这样：

block
object pen
fruit apple
people mike
block
electronic laptop
city dallas
fruit banana
object stapler
vehicle car
block
people george
fruit orange
vehicle truck
city austin
object hammer

在每个区块中，随机线上只有一个水果。每个块具有不同的行数。我想迭代这个文件，打印包括水果名字在内的所有内容，然后跳到下一个区块。一旦我在一个街区找到水果，检查下一行是否是水果是浪费时间。我只是想跳到下一个区块，但问题是我不知道该区块前面有多少条线。所以输出应该如下：

block
object pen
the fruit is: apple
block
electronic laptop
city dallas
the fruit is: banana
block
people george
the fruit is: orange

我可以用两种方式产生这个输出，一个：

flag = True
with open("sample.txt", "r") as f:
    for line in f.readlines():
        if line.split()[0] == 'fruit':
            print "the fruit is: " + line.split()[1]
            flag = False
        if line.split()[0] == 'block':
            flag = True
        if flag:
            print line

还有两个：

flag = False
with open("sample.txt", "r") as f:
    for line in f.readlines():
        if line.split()[0] == 'fruit':
            print "the fruit is: " + line.split()[1]
            flag = True
        if line.split()[0] == 'block':
            flag = False
        if flag:
            continue
        print line

但这不是我想要的。我的代码仍会检查每一行是否为水果。我想在水果之后跳过这些线直到阻止，并从那里继续。我怎么能跳这个？

Answer 1

from itertools import takewhile, dropwhile

def not_block(line): return line != 'block\n'
def not_fruit(line): return not line.startswith('fruit ')

with open("sample.txt", "r") as f:
    while True:
        for line in takewhile(not_fruit, dropwhile(not_block(f)):
            print line.rstrip()
        fruitline = next(f, None)
        if fruitline:
            print "the fruit is: " + fruitline.split()[1]
        else:
            break

Answer 2

您可以添加在找到block行后触发的内部循环。请注意，这假设您的数据格式正确（即每个块都有结果）。

with open('data.txt') as f:
    for line in f:
        line = line.strip()
        if line == 'block':
            print(line)
            for line in f:
                line = line.strip()
                if line.startswith('fruit '):
                    print('the fruit is:', line.split(None, 1)[1])
                    break
                else:
                    print(line)

如果数据文件真的很大，那么你可以做的另一件事就是更多参与，但速度要快得多mmap与find()一起使用。

Answer 3

叫我疯了但是我想用list comprehension和zip()对此进行不同的挖掘：

with open("sample.txt", "r") as file:
    lines = [line.strip('\n') for line in file.readlines()]

blocks = [i for i, j in enumerate(lines) if j == 'block']
fruits = [i for i, j in enumerate(lines) if 'fruit' in j]

for i, j in zip(blocks, fruits):
    print('\n'.join(lines[i:j+1]))

<强>输出：

block
object pen
fruit apple
block
electronic laptop
city dallas
fruit banana
block
people george
fruit orange

但是，如果每个block在下一个fruit之前始终跟block，则仅。

它看起来很漂亮，好吧。不要质疑我选择的武器......

如果在PYthon中满足条件，则跳过行直到文本文件中的下一个块

3 个答案: