Reading data from file with different number of components in each line in Python

Question

In this project I need to read the input file with unknown data and put it in a dictionary. The first column will always be name, while the rest will always be values. However, we don't know have many column for the values can it contain. For example:

name1;1;2;3;4
name2;1;1;1
name3;5;6
name4;9

I was thinking using split(';') but each row might have different columns.

for line in file:
   line = line.rstrip()
   name, value = line.split(';')
ValueError: too many values to unpack

Wanted final result:

d={name1:[1,2,3,4], name2:[1,1,1], name3:[5,6], name4:[9]}

Thank you so much for your help!

Answer 1

You're almost there. Splitting your line and using multiple assignment is the right idea. The missing piece is that you can use * in multiple assignment to make one portion have a variable length. Check out this article for an excellent rundown of various uses and idioms.

result = {}

with open('name_of_your_file') as file:
    for line in file:
        # Set name to the first element, and set value to the rest.
        name, *value = line.rstrip().split(';')
        result[name] = value

Answer 2

Using split(';') is a good idea here, this should work for you:

filename = 'path_to_your_file'
res={}
with open(filename, 'r') as file: #opens your file in reading mode
    for line in file: #reads the file line by line
        temp = line.rstrip('\n') #removes ending newline characters
        temp = temp.split(';') #split string by ';' into a list
        res[temp.pop(0)]=temp #uses the first element of the list as dictionary key, and the rest of the list as value
print(res)

Answer 3

After reading lines into the list you can use dict comprehension to do this -

reading all lines into list -

list1 = ['name1;1;2;3;4',
'name2;1;1;1',
'name3;5;6',
'name4;9']

using dict comprehension -

result_dict  ={item.split(';')[0]: item.split(';')[1:] for item in list1}
print(result_dict) 

output -

{'name1': ['1', '2', '3', '4'],
 'name2': ['1', '1', '1'],
 'name3': ['5', '6'],
 'name4': ['9']}