Coverting a list of strings into tuples using a function in python

Question

I'm relatively new to Python and just got introduced to functions. I'm working on an example and don't quite understand how to write the needed function.

The input to the function is a list of strings in the following format:

lines = ['1: 362.5815 162.5823\n', 
'2: 154.1328 354.1330\n', 
'3: 168.9325 368.9331\n',.. ]

I have to create a function that converts each item in the list into a tuple and stores the output in a new list.

To convert a single item of the list into a tuple, I am using the following code:

f1 = lines[0].split(" ")
f1tuple1 = tuple(f1)
f1tuple2 = (f1tuple[0], [float(f1tuple[1]), float(f1tuple[2])])

How do I perform the same action for all of the items in the list? I would really appreciate help in this matter.

Perhaps you can reduce your question to a single question, and post follow-up questions in a separate post. — Paul
– Paul, Commented Nov 23, 2021 at 12:35
And it will be greatly benefitting if you add what is your input and expected output, rather being verbose! — Kris
– Kris, Commented Nov 23, 2021 at 12:40
To perform a similar action on multiple values, you need to used iterators (for loop, while loop, etc.). You will perform that action for each item of the list, and store the result in another list. — Mobi Zaman
– Mobi Zaman, Commented Nov 23, 2021 at 12:40
Thanks everybody for the great help, and thanks for letting me know how to formulate my questions in a more useful way for next time :) — LucasTU
– LucasTU, Commented Nov 23, 2021 at 12:48

Tranbi · Accepted Answer · 2021-11-23 13:00:51Z

3

Edit: as rightfully pointed out in the comments, no need to use map.

I updated with use of a function and correct types (first tuple element as int):

lines = ['1: 362.5815 162.5823\n', '2: 154.1328 354.1330\n', '3: 168.9325 368.9331\n']

def create_tuples(lines):
    return [(int((y := x.split(" "))[0].strip(':')),
             [float(y[1]), float(y[2].strip('\n'))]
            ) for x in lines]

print(create_tuples(lines))

Output:

[(1, [362.5815, 162.5823]), (2, [154.1328, 354.133]), (3, [168.9325, 368.9331])]

Note: the assignment in the list comprehension only works for python >= 3.8

Old answer:

You can use map:

fituples = list(map(lambda x: tuple(x.strip("\n").split(" ")), lines))

Output:

[('1:', '362.5815', '162.5823'), ('2:', '154.1328', '354.1330'), ('3:', '168.9325', '368.9331')]

edited Nov 23, 2021 at 13:00

answered Nov 23, 2021 at 12:40

Tranbi

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2 Comments

LeopardShark Over a year ago

Don't use map with a lambda, particularly if you have to call list on it. Use a list comprehension.

Tranbi Over a year ago

oh you're right... thanks for pointing this out! completely over-complicated this one xD

Paul · Accepted Answer · 2021-11-23 12:43:11Z

1

With a 'for' loop you can run over all items in a list:

all_tuples = [] #<-- create a list to put all you tuples into
for value in lines: #<-- for loop, running through all values in you lines list
    f1 = value.split(" ") #<-- your code1
    f1tuple = tuple(f1) #<-- your code2
    f1tuple2 = (f1tuple[0], [float(f1tuple[1]), float(f1tuple[2])]) #<-- your code3
    all_tuples.append(f1tuple2) #<-- Adding the tuple to the list

all_tuples
[('1:', [362.5815, 162.5823]),
 ('2:', [154.1328, 354.133]),
 ('3:', [168.9325, 368.9331])]

As a function:

def get_all_tuples(lines): #<-- create a function
    all_tuples = []
    for value in lines:
        f1 = value.split(" ")
        f1tuple = tuple(f1)
        f1tuple2 = (f1tuple[0], [float(f1tuple[1]), float(f1tuple[2])])
        all_tuples.append(f1tuple2)
    return all_tuples #<-- return your all_tuples list

edited Nov 23, 2021 at 12:43

answered Nov 23, 2021 at 12:38

Paul

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1 Comment

LucasTU Over a year ago

I have to solve the problem using a function, is it possible to add the loop to a function, for eg: def function(lines): and then the loop

navyad · Accepted Answer · 2021-11-23 12:45:02Z

0

def items(lines):
   vals = [x.split(" ") for x in lines]
   return [(i[0], i[1], i[2]) for i in vals]

answered Nov 23, 2021 at 12:45

navyad

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Comments

Håkon Hægland · Accepted Answer · 2021-11-23 13:34:39Z

0

Using re :

tuples = []
for item in lines:
    if m := re.match(r"(\d+):\s+(\S+)\s+(\S+)", item):
        tuples.append([m.group(1), (m.group(2), m.group(3))])

answered Nov 23, 2021 at 13:34

Håkon Hægland

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