如何从txt文件中提取单独的第n行并将其分配给python 3中的key：value对？

Question

I'm learning how to code and I've run into a problem I don't have an answer to. I have a text file from which I have to make three dictionaries:

Georgie Porgie
87%
$$$
Canadian, Pub Food

Queen St. Cafe
82%
$
Malaysian, Thai

For the purpose of this thread I just want to ask how to extract the first line of each text block and store it as a key and the second line of each block as a value? I am supposed to write a code using nothing more but the very basic functions and loops.

Here is my code(once the file is opened):

d = {}
a = 0
for i in file:
    d[i] = i + 1
    a = i + 5
return(d)

Thank you.

Answer 1

First you have to read the file:

with open("data.txt") as file:
    lines = file.readlines()

The with clause ensures it is closed after it is read. Next, according to your description, a line contains a key if the index % 5 is 0. Then, the next line contains the value. With only "basic" elements of the language, you could construct your dictionary like this:

dic = {lines[idx].strip(): lines[idx + 1].strip() 
       for idx in range(0, len(lines), 5)}

This is a dictionary comprehension, which can also be written unfolded.

Now you can also zip the keys and values first, so you can iterate them quite easily. This makes the dictionary comprehension more readable. The strip method is necessary though, since we want to get rid of the line breaks.

entries = zip(lines[::5], lines[1::5])
dic = {key.strip(): value.strip() for key, value in entries}