List¶

add two lists¶

l = [1,2] + [3]

duplicat items in list¶

l = [1] * 3

nested list¶

#nested list
a = [[0] * 4 for i in range(3)]

diff between two lists¶

s1 = set(l1).difference(l2)

remove empty items¶

l2 = list(filter(None, l1))

check all None¶

l.count(None)==len(l)
all(v is None for v in l) #10x slower

remove duplicate in list and keep order¶

from collections import OrderedDict
lst = [1,2,4,2,5]
unique_list = list(OrderedDict.fromkeys(lst)) #python < 3.7
unique_list = list(dict.fromkeys(lst))        #python >= 3.7

transpose list of tuples¶

list_of_tuples = [(1,2), (3,4)]
list(zip(*list_of_tuples))

list of lists to csv¶

csv.writer(open('out.csv', 'w', newline='')).writerows(lls)