Question

我试图在找到“ X”时提取数据，并获取从该行到末尾的所有内容。我的代码仅给我下面的行。有没有办法在行中包含“ X”？

a = []
with open(file_path,'rU') as fp:
        for i,line in enumerate(fp):
            if "X" in line:
                #print (i, line)
                for line in fp:
                    a.append(line.split(' '))
                    print(a)

Answer 1

给出：

$ cat file.csv
line 1
line 2
line 3
line X
line 5
line 6
line 7

您可以使用itertools dropwhile：

import itertools as it

with open(file_path,'rU') as fp:
    a=[line.strip() for line in it.dropwhile(lambda l: 'X' not in l, fp)]

结果：

>>> a
['line X', 'line 5', 'line 6', 'line 7']

如果要在整个文件上使用enumerate，则可以拥有一个对象，该对象在测试后将保持True或False状态。通常称为FlipFlop，它在仅逐行读取文件的同时用于在文件中查找标记非常有用：

class FlipFlop: 
    def __init__(self, start_state, func):
        self.call=func
        self.state = start_state
    def __call__(self, st):
        if self.call(st): self.state=not self.state
        return self.state

with open(fn) as f_in:
    ff=FlipFlop(False, lambda s: 'X' in s)
    x_and_after=[(i, line.strip()) for i, line in enumerate(f_in) if ff(line)]

结果：

>>> x_and_after
[(3, 'line X'), (4, 'line 5'), (5, 'line 6'), (6, 'line 7')]

Answer 2

a = []
with open(file_path,'rU') as fp:
    for i, line in enumerate(fp):
        if 'X' in line:
            print('FOUND X [{}]: {}'.format(i, line))
            a.append(line.split(' '))
            for j, line in enumerate(fp, start=i+1):
                print('FOUND after X [{}]: {}'.format(j, line))
                a.append(line.split(' '))

print(a)

Answer 3

找到“ X”后，打开文件的第二个循环在行上开始。您可以添加“标志”并删除内部循环：

a = []
after_x = False

with open(file_path,'rU') as fp:
    for i,line in enumerate(fp):
        after_x = after_x or "X" in line
        if after_x:
            a.append(line.split(' '))
            print(a)

从特定行读取csv文件

3 个答案: