在不包括所需限制的包含字母范围内的文件中打印行

Question

我在使用该程序时遇到的问题是，即使我使用 >= <= 运算符，它也不包括边界。同样出于某种原因，输出的每个单词都由换行符分隔，而不是一个接一个地打印。

例如，如果所选的 .txt 文件包含：

Aladdin
Batman
Dinosaurs
Edgar
Fruitloop
Mongoose

选择的上限和下限是：

Batman
Fruitloop

程序打印：

Batman

Dinosaurs

Edgar

这是我正在处理的内容。非常感谢任何帮助！

import os

user_file = input() #reads name of user chosen .txt file containing alphabetized one word per line lists
lo_limit = input() #reads a user chosen word as the inclusive lower alphabetical limit
up_limit = input() #reads a user chosen word as the inclusive upper alphabetical limit

file_handle = open(user_file) #opens user chosen file

lines = file_handle.readlines() #creates by-line string of file contents


#if user chosen file contains words equal to or between bounds, prints words
for ln in lines:
    if ln >= lo_limit \
        and ln <= up_limit:
        print(ln)

Answer 1

好的，从打开文件的方式开始，使用这样的上下文管理器更容易打开它，然后它会为您处理 opening/closing。

with open('input.txt') as f:
    lines = f.readlines()

关于为什么您的代码不起作用，您必须考虑 file_handle.readlines() 正在执行和存储的内容。我相信您的印象是 lines 包含：

['Aladdin', 'Batman', 'Dinosaurs', 'Edgar', 'Fruitloop', 'Mongoose']

实际上它包含：

['Aladdin\n', 'Batman\n', 'Dinosaurs\n', 'Edgar\n', 'Fruitloop\n', 'Mongoose']

您可以像这样使用列表理解来剥离换行转义字符：

lines = [l.replace('\n', '') for l in lines]

那么你的逻辑应该没问题。总之，尝试这样的事情：

with open('input.txt') as f:
    lines = f.readlines()

lines = [l.replace('\n', '') for l in lines]

print(lines)

lo_limit = 'Batman'
up_limit = 'Fruitloop'

for ln in lines:
    if ln >= lo_limit and ln <= up_limit:
        print(ln)

给出输出：

['Aladdin', 'Batman', 'Dinosaurs', 'Edgar', 'Fruitloop', 'Mongoose']
Batman
Dinosaurs
Edgar
Fruitloop

Answer 2

这是不是如何select一系列行。这个案例是有效的，因为输入是 ascending 顺序。给它一个随机输入，你不会得到你期望的。

lines = """Aladdin
Batman
Dinosaurs
Edgar
Axe # input to break the ascending order
Fruitloop
Mongoose"""

lines = lines.split("\n")

for i in range(len(lines)):
    if "Batman" == lines[i]:
        for j in range(i, len(lines)):
            print(lines[j])
            if "Fruitloop" == lines[j]:
                break

要获得一定范围的行，您首先需要在行上循环，找到起始行，然后从该行开始循环，直到找到结束行。

另外：始终使用 with 子句打开文件：

with open(file, "r") as file:
    for line in file:
        # read line by line here

Answer 3

发生这种情况是因为当您执行 f.readlines() 这将 return 一个像这样的列表：

f.readlines()
>>>['Aladdin\n', 'Batman\n', 'Dinosaurs\n', 'Edgar\n', 'Fruitloop\n', 'Mongoose']

并且当您输入 up_limit=Edgar 时，您将比较每个列表 f.readlines() 与单词 Edgar，如下所示：

'Aladdin\n'>=lo_limit and 'Aladdin\n'<='Edgar'
>>>True
'Batman\n'>=lo_limit and ''Batman\n''<='Edgar'
>>>True
....
....
....

当成为 'Edgar\n' 的迭代时，您可以检查：

'Edgar'>='Edgar\n'
Out[6]: False

这就是 'Edgar' 未打印的原因。你可以试试：

import os

user_file = input() #reads name of user chosen .txt file containing alphabetized one word per line lists
lo_limit = input() #reads a user chosen word as the inclusive lower alphabetical limit
up_limit = input() #reads a user chosen word as the inclusive upper alphabetical limit

with open(str(user_file)) as file_handle:#opens user chosen file
    lines = file_handle.readlines()
    #if user chosen file contains words equal to or between bounds, prints words
    for ln in lines:
        if (ln > lo_limit) or (ln == lo_limit) or (ln < up_limit):
            print(ln)
            if (ln == up_limit+'\n'):
                break

或者您可以 select 按索引：

user_file = input() #reads name of user chosen .txt file containing alphabetized one word per line lists
lo_limit = str(input()) #reads a user chosen word as the inclusive lower alphabetical limit
up_limit = str(input()) #reads a user chosen word as the inclusive upper alphabetical limit

with open(str(user_file)) as file_handle:#opens user chosen file
    lines = file_handle.readlines() #creates by-line string of file contents    
    linesselected=lines[lines.index(lo_limit+'\n'):(lines.index(up_limit+'\n')+1)]
    for i in linesselected:
        print(i.replace('\n',''))

Answer 4

您需要将“>=”和“<=”替换为“>”和“<”。同时从每一行中删除“\n”。

要将结果留在同一行，您需要使用打印函数的结束属性。

保持这样：

user_file = input() #reads name of user chosen .txt file containing alphabetized one word per line lists
lo_limit = input() #reads a user chosen word as the inclusive lower alphabetical limit
up_limit = input() #reads a user chosen word as the inclusive upper alphabetical limit

file_handle = open(user_file) #opens user chosen file

lines = file_handle.readlines() #creates by-line string of file contents

#if user chosen file contains words equal to or between bounds, prints words
for ln in lines:
    ln = ln.replace('\n', '')
    if ln > lo_limit \
        and ln < up_limit:
        print(ln, end=' ')

输出：

$ python file.py 
arquivo.txt
Aladdin
Mongoose
Batman Dinosaurs Edgar Fruitloop

在不包括所需限制的包含字母范围内的文件中打印行

printing lines from a file within an inclusive alphabetical range not including desired limits

python

for-loop

readlines