[Python] Manipulation of elements in list (array) [Add / Delete]

Introduction

We have summarized the ** add / remove ** methods that are important for working with lists. Basically, write the code and output result with the following code.

ex.py

code = 'code'
print(code)
# code(Output result)

Add elements to a list (array) append, extend, insert

To add an element to a list (array) of type list or combine another list in Python, use the list methods ʻappend (), ʻextend (), ʻinsert ()`. In addition, there is also a method of assigning by specifying the position with the + operator or slice.

-Append element at the end: append () -Combine another list or tuple at the end (concatenate): extend (), + operator -Add (insert) element at specified position: insert () -Add another list or tuple to the specified position (insert): Use slice

-Append (): An element can be added at the end (last).

append().py

l = [0, 1, 2]
print(l)
# [0, 1, 2]

l.append(100)
print(l)
# [0, 1, 2, 100]

l.append('new')
print(l)
# [0, 1, 2, 100, 'new']

l.append([3, 4, 5])
print(l)
# [0, 1, 2, 100, 'new', [3, 4, 5]]

・ Extend () ・ ・ ・ You can combine another list or tuple at the end (last).

extend().py

l = [0, 1, 2]

l.extend([100, 101, 102])
print(l)
# [0, 1, 2, 100, 101, 102]

l.extend((-1, -2, -3))
print(l)
# [0, 1, 2, 100, 101, 102, -1, -2, -3]

#append()Unlike, it is stored character by character
l.extend('new')
print(l)
# [0, 1, 2, 100, 101, 102, -1, -2, -3, 'n', 'e', 'w']

#extend()Not a method+=But yes.
l += [5, 6, 7]
print(l)
# [0, 1, 2, 100, 101, 102, -1, -2, -3, 'n', 'e', 'w', 5, 6, 7]

-Insert (): An element can be added (inserted) at a specified position. Specify the position in the first argument and the element to be inserted in the second argument. The beginning (first) is 0. If the value is negative, -1 is one before the end (last).

insert().py

l = [0, 1, 2]

l.insert(0, 100)
print(l)
# [100, 0, 1, 2]

l.insert(-1, 200)
print(l)
# [100, 0, 1, 200, 2]

l.insert(0, [-1, -2, -3])
print(l)
# [[-1, -2, -3], 100, 0, 1, 200, 2]

-If you specify a range in a slice and substitute another list or tuple, all elements will be added (inserted).

insert().py

l = [0, 1, 2]

l[1:1] = [100, 200, 300]
print(l)
# [0, 100, 200, 300, 1, 2]

l[1:2] = [100, 200, 300]
print(l)
# [0, 100, 200, 300, 2]

Clear, pop, remove, del to remove elements in a list (array)

To remove a list (array) element of type list in Python, use the list methods claer (), pop (), remove (). In addition, there is also a method of specifying the position / range with an index or slice and deleting it with the del statement.

-Delete all elements: clear () -Delete the element at the specified position and get the value: pop () -Search for the same element as the specified value and remove the first element: remove () -Delete by specifying the position / range in the index slice: del

・ Clear () ・ ・ ・ Delete all elements

clear().py

l = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]

l.clear()
print(l)
# []

-Pop (): You can delete the element at the specified position with the list method pop () and get the value of that element.

pop().py

l = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]

print(l.pop(3))
# 4

print(l.pop(-2))
# 8

#If you omit the argument and do not specify the position, delete the last element
print(l.pop())
# 9

-Remove (): The list method remove () can search for the same element as the specified value and remove the first element.

remove().py

l = ['Alice', 'Bob', 'Charlie', 'Bob', 'Dave']

l.remove('Alice')
print(l)
# ['Bob', 'Charlie', 'Bob', 'Dave']

・ Del ・ ・ ・ Specify the element you want to delete by index. The beginning (first) is 0 and the end (last) is -1.

del.py

l = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]

del l[6]
print(l)
# [1, 2, 3, 4, 5, 6, 8]

del l[-1]
print(l)
# [1, 2, 3, 4, 5, 6, 7, 8]

#You can delete multiple elements at once by specifying a range with a slice.
del l[2:5]
print(l)
# [0, 1, 5, 6, 7, 8, 9]

Finally

I would be grateful if you could tell me if there is any other solution.