从文件内的字符串中将列表附加到列表中

Question

所以我有一些数据，我想要做的是创建每行的列表并将其附加到另一个列表中，但我无法想出任何关于如何仅打印第一或第二行的想法线。我尝试拆分整个数据，然后使用索引方法列出每一行，但这就是您手动执行的方式，但我想自动生成。因此，我们将不胜感激。

students = "joe 10 15 20 30 40 \
            bill 23 16 19 22 \
            sue 8 22 17 14 32 17 24 21 2 9 11 17 \
            grace 12 28 21 45 26 10 \
            John 14 32 25 16 89"


file_to_save = open("students.txt", "w")

file_to_save.writelines(students)

file_to_save.close()



file_to_read = open("students.txt", "r")

line = file_to_read.readline()

print(line)

file_to_read.close()

输出可能如下所示：

test = [[joe, 10, 15, 20, 30, 40], [bill, 23, 16, 19, 22], etc...]

Answer 1

您可以使用正则表达式将数据拆分为列表

>>> import re
>>> lines = [x.strip() for x in re.findall(r'\w+[\s\d]+', students)]
>>> lines
['joe 10 15 20 30 40', 'bill 23 16 19 22', 'sue 8 22 17 14 32 17 24 21 2 9 11 17', 'grace 12 28 21 45 26 10', 'John 14 32 25 16 89']

Answer 2

您可以为此使用 python itertools groupby

from itertools import groupby
students = "joe 10 15 20 30 40 \
        bill 23 16 19 22 \
        sue 8 22 17 14 32 17 24 21 2 9 11 17 \
        grace 12 28 21 45 26 10 \
        John 14 32 25 16 89"

Data=students.split(' ')
[list(g) for k,g in groupby(Data,key=lambda x:x == '') if not k]

输出：

[['joe', '10', '15', '20', '30', '40'], ['bill', '23', '16', '19', '22'], ['sue', '8', '22', '17', '14', '32', '17', '24', '21', '2', '9', '11', '17'], ['grace', '12', '28', '21', '45', '26', '10'], ['John', '14', '32', '25', '16', '89']]

Answer 3

问题是由于写入字符串造成的。您正在一行中输入数据，并且能够在一次调用中读取它。

注意：\ 与字符串中的 \n 不同。

为了解决这个问题，我同意在将数据从@abhilb 添加到文件之前预处理数据的解决方案

只需使用他的代码并包装我的代码即可解决您的问题。

import re

students = "joe 10 15 20 30 40 \
            bill 23 16 19 22 \
            sue 8 22 17 14 32 17 24 21 2 9 11 17 \
            grace 12 28 21 45 26 10 \
            John 14 32 25 16 89" ## Still a big chunk of line for your record. 


lines = [x.strip() for x in re.findall(r'\w+[\s\d]+', students)] # Credit to @abhilb

with open("students.txt", "w") as file_to_save: # Use this method to lose the hastle to close a file.. 
    for line in lines: # Lines Formed in the Students record as List of Strings... 
        print(line,file=file_to_save) # Saving them to the file with '\n' at the end..

index_of_lines_to_read = {1,3} # Index of the line you want to print.

with open("students.txt", "r") as file_to_read: # Use this method to lose the hastle to close a file..
    line = file_to_read.readline() # Reading first line...
    line_index = 1 # Keep check about the index we have read so far.. 
    while line: # Checking if we did not reach the EOF 
        if line_index in index_of_lines_to_read: # Checking if the current index needs to be printed else skip to next line.
            print(line,end="") # end="" compensate for the extra \n added using print above
        line = file_to_read.readline() # Read next line.. 
        line_index += 1 # Increment the current line index.

输出：

joe 10 15 20 30 40 sue 8 22 17 14 32 17 24 21 2 9 11 17

Answer 4

如果您想要读取一个文件然后只打印某一行，您可以尝试这样的操作：

def print_file_line(file_path: str, line_number: int):
    with open(file_path) as file:
        lines = file.readlines()
        print(lines[line_number])

print_file_line('students.txt', 1)

>>> '[bill, 23, 16, 19, 22]'

print_file_line('students.txt', 0)

>>> '[joe, 10, 15, 20, 30, 40]'