I'm trying to sort an array into multiple arrays by their starting letter
this is an example
list1 = ["apple", "banana", "carrot", "avocado"]
into this
a = ["apple", "avocado"]
b = ["banana"]
c = ["carrot"]
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4 Answers
As all the answers suggest, it is better to use a dictionary for this instead of making a lot of variables (and easier!). You can make this dictionary by looping over all fruits and add them to the right key (first letter).
list1 = ["apple", "banana", "carrot", "avocado"]
d = {}
for item in list1:
key = item[0]
if key in d.keys(): # if key already exists: append to list
d[key].append(item)
else: # if key does not exist: make new list
d[key] = [item]
Output:
{'a': ['apple', 'avocado'], 'b': ['banana'], 'c': ['carrot']}
Now you can get all fruits with letter a by doing d['a'].
Comments
Use itertools.groupby
from itertools import groupby
list1 = ["apple", "banana", "carrot", "avocado"]
print([list(val) for _, val in groupby(sorted(list1), key=lambda x: x[0])])
# [['apple', 'avocado'], ['banana'], ['carrot']]
# IF want dictionary
print({k : list(val) for k, val in groupby(sorted(list1), key=lambda x: x[0])})
# {'a': ['apple', 'avocado'], 'b': ['banana'], 'c': ['carrot']}
4 Comments
matszwecja
With this approach it might be hard to later get a list for specific letter.
Deepak Tripathi
This is what OP wants
a,b,c = [list(val) for _, val in groupby(sorted(list1), key=lambda x: x[0])] which will work for OPmatszwecja
And will not work should you add a single item starting with a different letter. Assigning each of them to a separate variable makes the code very inflexible.
Deepak Tripathi
Obviously, but I don't know exactly whats the end goal of OP.
It is propably better to save the seperate lists in a dictionary since you don't have to define variables by hand. Like this you can scale the number of elements in the list up.
dic = {}
for elem in list1:
dic.setdefault(elem[0], []).append(elem)
print(dic)
{'a': ['apple', 'avocado'], 'b': ['banana'], 'c': ['carrot']}
Comments
It's techincally not sorting, but categorising.
You can use a dictionary keyed by the first letter:
from collections import defaultdict
list1 = ["apple", "banana", "carrot", "avocado"]
d = defaultdict(list)
for el in list1:
d[el[0]].append(el)
print(dict(d)) # {'a': ['apple', 'avocado'], 'b': ['banana'], 'c': ['carrot']}
Resulting dict will contain lists for each letter, e.g d["a"] = ["apple", "avocado"]
