how to duplicate a list in python code example

Example 1: copy a list python

new_list = old_list.copy()
# or
new_list = old_list[:]

Example 2: duplicate in list python

a = [1,2,3,2,1,5,6,5,5,5]

import collections
print([item for item, count in collections.Counter(a).items() if count > 1])

## [1, 2, 5]

Example 3: python copy list

# Performance analysis by River on Stack Overflow
METHOD                  TIME TAKEN
b = [*a]                2.75180600000021
b = a * 1               3.50215399999990
b = a[:]                3.78278899999986  # Python2 winner
b = a.copy()            4.20556500000020
b = []; b.extend(a)     4.68069800000012
b = a[0:len(a)]         6.84498999999959
*b, = a                 7.54031799999984
b = list(a)             7.75815899999997
b = [i for i in a]      18.4886440000000
b = copy.copy(a)        18.8254879999999  # With `import copy`
b = []
for item in a:
    b.append(item)      35.4729199999997
  
# NOTE: Only for shallow copies, use copy.deepcopy for nested lists

Example 4: create copy of an array python

new_list = list.copy()

Example 5: copy one list to another python

thislist = ["apple", "banana", "cherry"]
mylist = thislist.copy()
print(mylist)

Example 6: python duplicate list elements

def duplicate_list_elements(_list : list):
    duplicated_list = []

    for element in _list:
        duplicated_list.append(element)
        duplicated_list.append(element)

    return duplicated_list