CODEWITHSUNDEEP
pythonstringlistdictionary
oakca
oakca

Reputation: 1568

add string to every element of a python list

I have a list made of a python dictionary keys via; list(dict.keys()).

dict.keys()
dict_keys(['South', 'North'])

I would like to add a string to the every element in the list = ['South', 'North'] like:

my_string = 'to_'

In the end I want to have list = ['to_South', 'to_North']

Is there a method I could use for this?

something like:

list.add_beginning_of_each_element('to_')

Upvotes: 9

Views: 17474

Answers (4)

Manualmsdos
Manualmsdos

Reputation: 1545

You can use lambda function:

lst = ['South', 'North']
result = list(map(lambda x: 'to_' + x, lst))

Upvotes: 5

U13-Forward
U13-Forward

Reputation: 71560

Or map:

>>> l = ['South', 'North']
>>> list(map('to_'.__add__,l))
['to_South', 'to_North']
>>>

There a add_prefix in pandas, so if you have a pandas dataframe, you can just use add_prefix to add to the columns, an example of making a dataframe out of a list and having them as columns:

>>> import pandas as pd
>>> pd.DataFrame(columns=['South', 'North']).add_prefix('to_').columns.tolist()
['to_South', 'to_North']

Upvotes: 11

Dani Mesejo
Dani Mesejo

Reputation: 61910

Use a list comprehension:

lst = ['South', 'North']
result = ['to_' + direction for direction in lst]

As an alternative you could use map:

def add_to_beginning(s, start='to_'):
    return start + s

lst = ['South', 'North']

result = list(map(add_to_beginning, lst))
print(result)

Upvotes: 14

DeepSpace
DeepSpace

Reputation: 81594

dict.keys() does not return the actual keys, it merely returns a view (=copy) of the keys.

If you want to print a modified version of the keys:

print(['to_' + key for key in d.keys()])

If you want to change the actual keys:

d = {'to_' + key: value for key, value in d.items()}

Upvotes: 1

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