[1,2,3]
len(arrayName) # size of list

# add value to all elements of list
my_list=[1,3,5,7,8]
new_list = [x+1 for x in my_list] # [2,4,6,8,9]

list.append(obj)
list.extend(list)
list.index(obj)
list.count(obj) # count appearance of obj

# array to string and string to array
sentence = ["there", "is", "no", "spoon"]
' '.join(sentence) #'there is no spoon'

list=[3.1,121.2,34.1]
', '.join(map(str,list)) #'3.1, 121.2, 34.1'

'3.1, 121.2, 34.1'.split(', ') #['3.1','121.2','34.1']
# 2nd number make how many split point
'3.1, 121.2, 34.1'.split(', ',1) #['3.1','121.2, 34.1'] 

# list sort (modify itself)
versionList.sort(reverse=1) # higher to lower
versionList.sort() 

str([-4, -2, 0, 2, 4]) # '[-4,-2,0,2,4]'
bb_str ='_'.join(map(str, bb)) # -4_-2_0_2_4

# list compare
[-4, -2, 0, 2, 4] == [-4, -2, 0, 2, 3] # false

# multiple list operation

wMap_zero_Jnt=[x for x in wMap_All_Jnt if x not in wMap_Jnt_tgt] # remove list from list

a = [1, 2, 3, 4, 5]
b = [9, 8, 7, 6, 5]
common = set(a) & set(b) #[5], no order applied

[i for i, j in zip(a, b) if i == j] # [5] for equal-sized lists, which order matters 

version_list_prefix=["previous","current"]
version_list_postfix=["A","B"]
version_list_color=["rgb(255, 128, 128)","rgb(85, 170, 255)"]
for each,post,color in zip(version_list_prefix,version_list_postfix,version_list_color):
    print(each+" "+post+" is "+color)
    
# list slice operation
# n = len(L)
# item = L[index]
# seq = L[start:stop]
# seq = L[start:stop:step]
seq = L[::2] # get every other item, starting with the first
seq = L[1::2] # get every other item, starting with the second

seq=L[::-1] # reverse reading list
list(reversed(seq)) # generate a list reversed
L.reverse() # reverse list, it changed original list
seq=L[::-2] # reverse reading list, and get every other item

list=[1,2,3,4,5,6]
seq=list[::-2] # [6,4,2]

# list to pair list
info = ['name','John', 'age', '17', 'address', 'abc']
info_pair = zip(info[::2], info[1::2])
# [('name', 'John'), ('age', '17'), ('address', 'abc')] 

# list flatten, and remove duplicates
nestList = [[2,3],[1,2,4],[5,6]]
flatList = set(sum(nestList,[])) # for small list of 2 level nest

# delete a element from list
a = [1,2,3,4]
del(a[2]) # [1,2,4]

# for large list
import itertools
flatList = set( list(itertools.chain.from_iterable(nestList)) ) # for same type element list, no mix of list and element like [[5],6], as it will error

import operator
flatList = set( reduce(operator.add, map(list, nestList)) ) # like itertool, but it will not error for mix of list and element situation

# for any mix list
def flatFn(mainList):
    newList = []
    for each in mainList:
        if isinstance(each, (list, tuple)):
            newList.extend( flatFn(each) )
        else:
            newList.append(each)
    return newList
    
flatList = set( flatFn(nestList) )