Question

我的文件是“xml.txt”，内容如下：

books.xml 
news.xml
mix.xml

如果我使用readline（）函数，它会在所有文件的名称后附加“\ n”，这是一个错误，因为我想打开xml.txt中包含的文件。我写了这个：

fo = open("xml.tx","r")
for i in range(count.__len__()): #here count is one of may arrays that i'm using
    file = fo.readline()
    find_root(file) # here find_root is my own created function not displayed here

运行此代码时遇到

错误：

IOError: [Errno 2] No such file or directory: 'books.xml\n'

Answer 1

最后只删除换行符：

line = line.rstrip('\n')

readline保留换行符的原因是，您可以区分空行（具有换行符）和文件末尾（空字符串）。

Answer 2

来自Best method for reading newline delimited files in Python and discarding the newlines?

lines = open(filename).read().splitlines()

Answer 3

您可以使用字符串对象的.rstrip()方法来获取删除了尾随空格（包括换行符）的版本。

E.g：

find_root(file.rstrip())

Answer 4

为文件使用上下文管理器是更好的风格，len()而不是调用.__len__()

with open("xml.tx","r") as fo:
    for i in range(len(count)): #here count is one of may arrays that i'm using
        file = next(fo).rstrip("\n")
        find_root(file) # here find_root is my own created function not displayed here

Answer 5

要从最后删除换行符，您还可以使用以下内容：

for line in file:
   print line[:-1]

Answer 6

我只是为了好奇而定时。以下是各种大文件的结果。

tldr; 文件读取然后拆分似乎是大文件上最快的方法。

with open(FILENAME, "r") as file:
    lines = file.read().split("\n")

但是，如果你需要循环遍历这些行，那么你可能想要：

with open(FILENAME, "r") as file:
    for line in file:
        line = line.rstrip("\n")

Python 3.4.2

import timeit


FILENAME = "mylargefile.csv"
DELIMITER = "\n"


def splitlines_read():
    """Read the file then split the lines from the splitlines builtin method.

    Returns:
        lines (list): List of file lines.
    """
    with open(FILENAME, "r") as file:
        lines = file.read().splitlines()
    return lines
# end splitlines_read

def split_read():
    """Read the file then split the lines.

    This method will return empty strings for blank lines (Same as the other methods).
    This method may also have an extra additional element as an empty string (compared to
    splitlines_read).

    Returns:
        lines (list): List of file lines.
    """
    with open(FILENAME, "r") as file:
        lines = file.read().split(DELIMITER)
    return lines
# end split_read

def strip_read():
    """Loop through the file and create a new list of lines and removes any "\n" by rstrip

    Returns:
        lines (list): List of file lines.
    """
    with open(FILENAME, "r") as file:
        lines = [line.rstrip(DELIMITER) for line in file]
    return lines
# end strip_readline

def strip_readlines():
    """Loop through the file's read lines and create a new list of lines and removes any "\n" by
    rstrip. ... will probably be slower than the strip_read, but might as well test everything.

    Returns:
        lines (list): List of file lines.
    """
    with open(FILENAME, "r") as file:
        lines = [line.rstrip(DELIMITER) for line in file.readlines()]
    return lines
# end strip_readline

def compare_times():
    run = 100
    splitlines_t = timeit.timeit(splitlines_read, number=run)
    print("Splitlines Read:", splitlines_t)

    split_t = timeit.timeit(split_read, number=run)
    print("Split Read:", split_t)

    strip_t = timeit.timeit(strip_read, number=run)
    print("Strip Read:", strip_t)

    striplines_t = timeit.timeit(strip_readlines, number=run)
    print("Strip Readlines:", striplines_t)
# end compare_times

def compare_values():
    """Compare the values of the file.

    Note: split_read fails, because has an extra empty string in the list of lines. That's the only
    reason why it fails.
    """
    splr = splitlines_read()
    sprl = split_read()
    strr = strip_read()
    strl = strip_readlines()

    print("splitlines_read")
    print(repr(splr[:10]))

    print("split_read", splr == sprl)
    print(repr(sprl[:10]))

    print("strip_read", splr == strr)
    print(repr(strr[:10]))

    print("strip_readline", splr == strl)
    print(repr(strl[:10]))
# end compare_values

if __name__ == "__main__":
    compare_values()
    compare_times()

结果：

run = 1000
Splitlines Read: 201.02846901328783
Split Read: 137.51448011841822
Strip Read: 156.18040391519133
Strip Readline: 172.12281272950372

run = 100
Splitlines Read: 19.956802833188124
Split Read: 13.657361738959867
Strip Read: 15.731161020969516
Strip Readlines: 17.434831199281092

run = 100
Splitlines Read: 20.01516321280158
Split Read: 13.786344555543899
Strip Read: 16.02410587620824
Strip Readlines: 17.09326775703279

文件读取然后拆分似乎是大文件上最快的方法。

注意：read then split（“\ n”）在列表末尾会有一个额外的空字符串。

注意：然后读取splitlines（）检查更多，然后“\ n”可能“\ r \ n”。

Answer 7

@Lars Wirzenius回答的用例：

with open("list.txt", "r") as myfile:
    for lines in myfile:
        lines = lines.rstrip('\n')    # the trick
        try:
            with open(lines) as myFile:
                print "ok"
        except IOError as e:
            print "files does not exist"

Answer 8

# mode : 'r', 'w', 'a'
f = open("ur_filename", "mode")
for t in f:
    if(t):
        fn.write(t.rstrip("\n"))

＆＃34;如果＆＃34;条件将检查该行是否有字符串，如果是，则下一行将删除＆＃34; \ n＆＃34;在最后并写入文件。代码测试。 ;）

从文件读取行而不在末尾附加“\ n”

8 个答案: