如何从 Python 中的文件中删除“\n”行？

Question

我需要检查我正在使用的 .csv 文件是否以超过 1 "\n" 行结尾。如果它发现不止一个空行，它会删除除一个以外的所有空行。

我的代码是：

import os
from pathlib import Path


def remove_blanks():
    dirname = os.path.dirname(os.path.abspath(__file__))
    path: Path = Path(os.path.join(dirname, "data.csv"))
    with open(path, "r+") as op:
        lines = op.readlines()
        for line in lines:
            if line == "\n":
                op.write(line.rstrip("\n"))

.csv 文件类似于 ['01-01-2019,0,0,0\n', '18-05-2019,33,31,48\n', '\n', '\n', '\n']，我想要的输出是 ['01-01-2019,0,0,0\n', '18-05-2019,33,31,48\n', '\n']，但它似乎无法删除任何行。

Answer 1

最简单的方法是，如果您看到一个空行，那么在写一个 non[=24= 之前写一个]-空行。

pre = "" for line in lines: if line == "\n": pre = line else: op.write(pre) op.write(line) pre = "\n" op.write(pre)

这会将任何空行序列减少为单个空行，并在写入 non-empty 行或文件末尾之前写入该行。当pre为空串时，写成no-op.

如果要在文件中间保留多个空行，在pre中找到空行的顺序，在文件末尾只写一个如果 pre 不为空，则空行（而不是 pre 本身）。

pre = "" for line in lines: if line == "\n": pre += line else: op.write(pre) op.write(line) pre = "" if pre: op.write("\n")

Answer 2

您可以尝试使用 Counter()。

import os
from pathlib import Path
from collections import Counter

def remove_blanks():
    dirname = os.path.dirname(os.path.abspath(__file__))
    path: Path = Path(os.path.join(dirname, "data.csv"))
    with open(path, "r+") as op:
        lines = op.readlines()
        for line in lines:
            count = Counter()
            # Add 1 for every time word appears in line
            for word in line:
                count[word] += 1
            # Change the number of newlines to 1
            if count['\n'] > 1:
                count['\n'] = 1
            # Returns list with the number of elements
            line = list(count.elements())

Answer 3

哎呀，永远不要重写您正在阅读的文件：它可能无法工作，或者充其量只会导致维护噩梦。

如果文件足够小，可以放入主内存，那么对您的代码稍作改动就足够了：

import os.path
from pathlib import Path


def remove_blanks():
    dirname = os.path.dirname(os.path.abspath(__file__))
    path: Path = Path(os.path.join(dirname, "data.csv"))
    with open(path, "r") as op:
        lines = op.readlines()  # read lines in memory
    with open(path("w") as op:  # re-write everything from the beginning
        flag = False     
        for line in lines:
            if line == "\n":
                if not flag:
                    op.write(line)
                flag = True
            else:
                op.write(line)
                # flag = False  # uncomment if you want to keep one blank line 
                                # per group of consecutive lines

Answer 4

我用这段代码设法解决了这个问题：

import os
from pathlib import Path


def remove_blanks():
    dirname = os.path.dirname(os.path.abspath(__file__))
    path: Path = Path(os.path.join(dirname, "data.csv"))
    with open(path, "r") as op:
        lines = op.readlines()  # read lines in memory
    with open(path, "w") as op: # re-write everything from the beginning
        for line in lines:
            if line != "\n":
                op.write(line)
            else:
                continue

它可以删除每一个多余的新行，无论它在文件中的什么位置。

感谢所有帮助过我的人！

如何从 Python 中的文件中删除“\n”行？

How can I delete "\n" lines from a file in Python?

python

csv

readlines