def inverse_dict(obj):
inv_obj = {}
for key, value in obj.items():
inv_obj.setdefault(value, list()).append(key)
return inv_objages = {
hsleonis
/ inverse_dict.md
Created
May 25, 2020 22:41
Inverts a dictionary with non-unique hashable values.
from math import ceil
def batch(lst, size):
return list(
map(lambda x: lst[x * size:x * size + size],
list(range(0, ceil(len(lst) / size)))))
def check_prop(fn, prop):
return lambda obj: fn(obj[prop])check_age = check_prop(lambda x: x >= 18, 'age')
user = {'name': 'Mark', 'age': 18}
check_age(user) # True
def str_capitalize(s, lower_rest=False):
return s[:1].upper() + (s[1:].lower() if lower_rest else s[1:])str_capitalize('fooBar') # 'FooBar'
str_capitalize('fooBar', True) # 'Foobar'
from re import sub
def str_camelcase(s):
s = sub(r"(_|-)+", " ", s).title().replace(" ", "")
return s[0].lower() + s[1:]str_camelcase('some_database_field_name') # 'someDatabaseFieldName'
def byte_size(s):
return len(s.encode('utf-8'))byte_size('😀') # 4
byte_size('Hello World') # 11
hsleonis
/ split_by.md
Last active
May 25, 2020 21:37
Splits values into two groups according to a function.
def split_by(lst, fn):
return [
[x for x in lst if fn(x)],
[x for x in lst if not fn(x)]
]split_by(
def split_list(lst, filter):
return [
[x for i, x in enumerate(lst) if filter[i] == True],
[x for i, x in enumerate(lst) if filter[i] == False]
]split_list(['beep', 'boop', 'foo', 'bar'], [True, True, False, True]) # [ ['beep', 'boop', 'bar'], ['foo'] ]
hsleonis
/ mean_by.md
Last active
May 25, 2020 22:14
Returns the average of a list, after mapping each element to a value using the provided function.
def mean_by(lst, f=lambda el: el):
return sum(map(f, lst), 0.0) / len(lst)mean_by([{ 'n': 4 }, { 'n': 2 }, { 'n': 8 }, { 'n': 6 }], lambda p: p['n']) # 5.0def mean(*args):
return sum(args, 0.0) / len(args)mean(*[1, 2, 3]) # 2.0
mean(1, 2, 3) # 2.0