How do i get a list of lowercase letters in python?

Question

Simply use the Python string lower() method to convert every element in a list of strings into lowercase. It will convert given into lowercase letters in Python.

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Example make the elements in a list of strings lowercase in Python
Another example
How do you make a lowercase list in Python?
How do you lowercase all strings in a list?
How do I get a list of letters in Python?
How do you define range of alphabets in Python?

str.lower()

Example make the elements in a list of strings lowercase in Python

Simple python code:

Let’s try, given list ["a", "B", "C"] convert into ["a", "b", "c"].

Iterate through string_list
Convert each string to lowercase

strList = ["a", "B", "C"]

for i in range(len(strList)):
    strList[i] = strList[i].lower()

print(strList)

Output:

How do i get a list of lowercase letters in python?

Another example

Use list comprehension to convert list strings into lowercase words.

strList = ["AA", "BB", "CC"]

strList = [x.lower() for x in strList]

print(strList)

Output:

[‘aa’, ‘bb’, ‘cc’]

Do comment if you have any doubts and suggestions on this Python list code.

Note: IDE: PyCharm 2021.3.3 (Community Edition)

Windows 10
Python 3.10.1
All Python Examples are in Python 3, so Maybe its different from python 2 or upgraded versions.

Degree in Computer Science and Engineer: App Developer and has multiple Programming languages experience. Enthusiasm for technology & like learning technical.

I have a Python list variable that contains strings. Is there a function that can convert all the strings in one pass to lowercase and vice versa, uppercase?

asked Nov 26, 2009 at 5:15

1

It can be done with list comprehensions

>>> [x.lower() for x in ["A", "B", "C"]]
['a', 'b', 'c']
>>> [x.upper() for x in ["a", "b", "c"]]
['A', 'B', 'C']

or with the map function

>>> list(map(lambda x: x.lower(), ["A", "B", "C"]))
['a', 'b', 'c']
>>> list(map(lambda x: x.upper(), ["a", "b", "c"]))
['A', 'B', 'C']

answered Nov 26, 2009 at 5:19

YOUYOU

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5

Besides being easier to read (for many people), list comprehensions win the speed race, too:

$ python2.6 -m timeit '[x.lower() for x in ["A","B","C"]]'
1000000 loops, best of 3: 1.03 usec per loop
$ python2.6 -m timeit '[x.upper() for x in ["a","b","c"]]'
1000000 loops, best of 3: 1.04 usec per loop

$ python2.6 -m timeit 'map(str.lower,["A","B","C"])'
1000000 loops, best of 3: 1.44 usec per loop
$ python2.6 -m timeit 'map(str.upper,["a","b","c"])'
1000000 loops, best of 3: 1.44 usec per loop

$ python2.6 -m timeit 'map(lambda x:x.lower(),["A","B","C"])'
1000000 loops, best of 3: 1.87 usec per loop
$ python2.6 -m timeit 'map(lambda x:x.upper(),["a","b","c"])'
1000000 loops, best of 3: 1.87 usec per loop

answered Nov 26, 2009 at 5:54

Ned DeilyNed Deily

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5

>>> list(map(str.lower,["A","B","C"]))
['a', 'b', 'c']

Amit JS

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answered Nov 26, 2009 at 5:24

ghostdog74ghostdog74

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2

List comprehension is how I'd do it, it's the "Pythonic" way. The following transcript shows how to convert a list to all upper case then back to lower:

pax@paxbox7:~$ python3
Python 3.5.2 (default, Nov 17 2016, 17:05:23) 
[GCC 5.4.0 20160609] on linux
Type "help", "copyright", "credits" or "license" for more information.

>>> x = ["one", "two", "three"] ; x
['one', 'two', 'three']

>>> x = [element.upper() for element in x] ; x
['ONE', 'TWO', 'THREE']

>>> x = [element.lower() for element in x] ; x
['one', 'two', 'three']

answered Nov 26, 2009 at 5:23

paxdiablopaxdiablo

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5

For this sample the comprehension is fastest

$ python -m timeit -s 's=["one","two","three"]*1000' '[x.upper for x in s]'
1000 loops, best of 3: 809 usec per loop

$ python -m timeit -s 's=["one","two","three"]*1000' 'map(str.upper,s)'
1000 loops, best of 3: 1.12 msec per loop

$ python -m timeit -s 's=["one","two","three"]*1000' 'map(lambda x:x.upper(),s)'
1000 loops, best of 3: 1.77 msec per loop

answered Nov 26, 2009 at 5:59

John La RooyJohn La Rooy

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a student asking, another student with the same problem answering :))

fruits=['orange', 'grape', 'kiwi', 'apple', 'mango', 'fig', 'lemon']
newList = []
for fruit in fruits:
    newList.append(fruit.upper())
print(newList)

Anubis

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answered Nov 6, 2015 at 10:08

CristinaCristina

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mylist = ['Mixed Case One', 'Mixed Case Two', 'Mixed Three']
print(list(map(lambda x: x.lower(), mylist)))
print(list(map(lambda x: x.upper(), mylist)))

TechJ

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answered Nov 26, 2009 at 5:24

ChiraelChirael

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A much simpler version of the top answer is given here by @Amorpheuses.

With a list of values in val:

valsLower = [item.lower() for item in vals]

This worked well for me with an f = open() text source.

answered Nov 19, 2019 at 19:02

WhooNoWhooNo

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0

Solution:

>>> s = []
>>> p = ['This', 'That', 'There', 'is', 'apple']
>>> [s.append(i.lower()) if not i.islower() else s.append(i) for i in p]
>>> s
>>> ['this', 'that', 'there', 'is','apple']

This solution will create a separate list containing the lowercase items, regardless of their original case. If the original case is upper then the list s will contain lowercase of the respective item in list p. If the original case of the list item is already lowercase in list p then the list s will retain the item's case and keep it in lowercase. Now you can use list s instead of list p.

ADyson

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answered May 31, 2018 at 8:24

SunilSunil

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If your purpose is to matching with another string by converting in one pass, you can use str.casefold() as well.

This is useful when you have non-ascii characters and matching with ascii versions(eg: maße vs masse).Though str.lower or str.upper fails in such cases, str.casefold() will pass. This is available in Python 3 and the idea is discussed in detail with the answer https://stackoverflow.com/a/31599276/4848659.

>>>str="Hello World";
>>>print(str.lower());
hello world
>>>print(str.upper());
HELLO WOLRD
>>>print(str.casefold());
hello world

answered Oct 16, 2018 at 0:18

GimhaniGimhani

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You could try using:

my_list = ['india', 'america', 'china', 'korea']

def capitalize_list(item):
    return item.upper()

print(list(map(capitalize_list, my_list)))

U12-Forward

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answered Feb 9, 2020 at 15:50

Here's another solution to the problem, but I don't recommend using it. Just putting it here for completion of this topic since this solution wasn't added before.

import timeit

def foo1():
    L = ["A", "B", "C", "&"]
    return [x.lower() for x in L]
def foo2():
    L = ["A", "B", "C", "&"]
    return "%".join(L).lower().split("%")

for i in range(10):
    print("foo1", timeit.timeit(foo1, number=100000))
    print("foo2", timeit.timeit(foo2, number=100000), end="\n\n")

foo1 0.0814619
foo2 0.058695300000000006

foo1 0.08401910000000004
foo2 0.06001100000000004

foo1 0.08252670000000001
foo2 0.0601641

foo1 0.08721100000000004
foo2 0.06254229999999994

foo1 0.08776279999999992
foo2 0.05946070000000003

foo1 0.08383590000000007
foo2 0.05982449999999995

foo1 0.08354679999999992
foo2 0.05930219999999997

foo1 0.08526650000000013
foo2 0.060690699999999875

foo1 0.09940110000000013
foo2 0.08484609999999981

foo1 0.09921800000000003
foo2 0.06182889999999985

answered Apr 25 at 8:21

If you are trying to convert all string to lowercase in the list, You can use pandas :

import pandas as pd

data = ['Study', 'Insights']

pd_d = list(pd.Series(data).str.lower())

output:

['study', 'insights']

answered Oct 30, 2019 at 9:29

Aaditya UraAaditya Ura

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How do you make a lowercase list in Python?

Lowercase. To convert a string to lowercase in Python, use the built-in lower() method of a string. To convert a list of strings to lowercase, use a loop. Alternatively, you can also use a list comprehension.

How do you lowercase all strings in a list?

Use str. lower() to convert every element in a list of strings into lowercase. Use a for loop to iterate through each element in a list of strings by index.

How do I get a list of letters in Python?

The easiest way to load a list of all the letters of the alphabet is to use the string. ascii_letters , string. ascii_lowercase , and string. ascii_uppercase instances.

How do you define range of alphabets in Python?

To produce a range of letters (characters) in Python, you have to write a custom function that:.

Takes start and end characters as input..

Converts start and end to numbers using ord() function..

Generates a range of numbers between start and end..

Converts the numbers back to characters..

Yields the characters..

programming python Alphabet Python Lower Python Number list python

How do i get a list of lowercase letters in python?

Example make the elements in a list of strings lowercase in Python

Another example

How do you make a lowercase list in Python?

How do you lowercase all strings in a list?

How do I get a list of letters in Python?

How do you define range of alphabets in Python?

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