Reading from text file. Making it to a dictionary

Question

I have a sample.txt file:

1 7 14
3 3 10
1 1 3

What I wrote (it is wrong but at least something)(there were better ones, but I couldn't remake them):

content = []
with open ("sample.txt","r",encoding="utf-8") as file:
    for line in file:
        line = file.readline().strip().split(" ")
        mydict = {"A":int(file.readline().strip().split(" ")[0]),
                  "B":int(file.readline().strip().split(" ")[1]),
                  "C":int(file.readline().strip().split(" ")[2])}
        content.append(mydict)

print (content)

expected output:

[ {"A":1,"B":7,"C":14},{"A":3,"B":3,"C":10},{"A":1,"B":1,"C":3} ]

Neither of them worked sadly. There were 3 problems typically:

When I try to convert the values with int()
First or last line is missing (problem with indexing)
At the values I can't write just simply line[0], because that way it is not working (why?)

I am really newbie, maybe it will be good for someone else who is doing the same as me and noob like me.

Does this answer your question? [convert csv file to list of dictionaries](https://stackoverflow.com/questions/21572175/convert-csv-file-to-list-of-dictionaries) — buran, Jan 10 '21 at 21:00
I hope this is a homework assignment, to teach you how to handle files and dictionaries. Otherwise, I'd suggest not to create such a list of dictionaries at all. — zvone, Jan 10 '21 at 21:04
What you are missing is that `for line in file:` *already* reads the file a line at a time. Every call to `readline()` reads *another* line and so your input gets used up much quicker than you expect. Calling `readline()` is a lower-level (and older) approach that is an *alternative* to `for line in file:`. — BoarGules, Jan 10 '21 at 21:14

score 2 · Accepted Answer · answered Jan 10 '21 at 21:00

You are very close. The line variable is what you need:

content = []
with open ("sample.txt","r",encoding="utf-8") as file:
    for line in file:
        line = line.strip().split(" ")
        mydict = {"A":int(line[0]),
                  "B":int(line[1]),
                  "C":int(line[2])}
        content.append(mydict)

print (content)

Joran Beasley · Answer 2 · 2021-01-10T21:13:56.463

1

there is a builtin csv reader that takes care of this for you very easily

import csv

result = list(csv.DictReader(open("myfile.csv"),["A","B","C"],delimiter=" "))

edited Jan 10 '21 at 21:13

answered Jan 10 '21 at 21:08

Joran Beasley

110,522
12
160
179

Countour-Integral · Answer 3 · 2021-01-10T21:41:33.293

The thing you are doing wrong is at

line = file.readline().strip().split(" ")

Here you are inside of a for that loops through each line. Check the output of the following

with open("sample.txt") as file:
    for line in file:
        print(line)

This will print each of the lines of the file. So on first iteration it will print 1 7 14 on the second 3 3 10 and on the third 1 1 3.

Now you are looping through each of the lines But while you are doing that you are reading the next line. Just check this out.

with open("sample.txt") as file:
    count = 0
    for line in file:
        print(count, "This is current line", line)
        print(count, "This is the next line",file.readline())
        count += 1 # count = count + 1

This simply outputs

0 This is current line 1 7 14
0 This is the next line 3 3 10
1 This is current line 1 1 3
1 This is the next line

So what you are doing is you are going trhough 2 lines at a time and thus you are correctly getting an index error.

Instead what you will have to do is just remove all the readline and read one line at a time. This is almost the same as @quamrana snippet.

content = []
with open ("sample.txt","r",encoding="utf-8") as file:
    for line in file: # Only 1 line at a time
        line = line.strip().split(" ") # .strip() removes all white space in the begging and end and also newlines
        mydict = {"A":int(line[0]),
                  "B":int(line[1]),
                  "C":int(line[2])}
        content.append(mydict)

Thank you, now I understand this. But when you wrote line.split(" ").strip() it wasn't good. But when it is strip().split(" ") it works. Why? (One of methods makes it a list if I remember correctly) — Ilovemilk, Jan 10 '21 at 21:39
You are correct `line.split(" ")` is a list and this is calling `.strip()` on a list. The `strip().split(" ")` is first a string then is split. This is my mistake. — Countour-Integral, Jan 10 '21 at 21:41

score 0 · Answer 4 · answered Jan 10 '21 at 21:33

0

in case you already using pandas:

import pandas as pd

df = pd.read_csv("sample.txt",sep=' ', header=None)
df.columns = ['A','B','C']
print(df.to_dict('records'))

answered Jan 10 '21 at 21:33

adir abargil

5,495
3
19
29

Reading from text file. Making it to a dictionary

4 Answers4