*Memos:
- My post explains the list with slicing and copy.
- My post explains the useful functions for a list (1).
- My post explains the useful functions for a list (2).
- My post explains a tuple.
- My post explains a set and shallow copy.
- My post explains a dictionary, the dictionary with keying and copy.
- My post explains variable assignment.
- My post explains shallow copy and deep copy.
A list:
- is an ordered collection to use non-huge data not to get
MemoryError. - allows duplicated elements (even with different types).
- is mutable so it can be changed.
- can have any mixed types of elements.
- can be enlarged with
*and a number. - can be created by list() with or without a list, tuple, set, dictionary, iterator, string or range() or by a list comprehension.
- can be used with len() to get the length.
- can be accessed by indexing or slicing.
- can be copied to refer to a different list.
A list is for non-huge data otherwise it gets MemoryError.
You can create a list as shown below:
v = [] # Empty 1D list
v = list() # Empty 1D list
v = ['a', 'b', 'c', 'd', 'e', 'f', 'g', 'h'] # 1D list
v = ['a', 'b', 'c', 'a', 'b', 'c'] # 1D list
v = ['a', 'b', 'c'] * 3 # 1D list
v = ['a', 'b', 'c', 'd', ['e', 'f', 'g', 'h']] # 2D list
v = [['a', 'b', 'c', 'd'], ['e', 'f', 'g', 'h']]# 2D list
v = [['a', 'b', 'c']] * 3 # 2D list
v = [['a', 'b', 'c', 'd'], [['e', 'f'], ['g', 'h']]] # 3D list
v = [[['a', 'b'], ['c', 'd']], [['e', 'f'], ['g', 'h']]] # 3D list
v = [[['a', 'b', 'c']]] * 3 # 3D list
v = [1, 1.0, 1.0+0.0j, True]
v = ['a', 2, 2.3, 2.3+4.5j, True, [2, 3], (2, 3), {2, 3}, {'a':'A'}]
# No error
A list is an ordered collection as shown below:
v = ['a', 'b', 'c', 'd', 'e']
print(v) # ['a', 'b', 'c', 'd', 'e']
A list allows duplicated elements (even with different types) as shown below:
v = ['a', 'b', 'c', 'a', 'b', 'c']
print(v) # ['a', 'b', 'c', 'a', 'b', 'c']
v = [1, 1.0, 1.0+0.0j, True]
print(v) # [1, 1.0, (1+0j), True]
A list can have any mixed types of elements as shown below:
v = ['a', 2, 2.3, 2.3+4.5j, True, [2, 3], (2, 3), {2, 3}, {'a':'A'}]
print(v)
# ['a', 2, 2.3, (2.3+4.5j), True, [2, 3], (2, 3), {2, 3}, {'a': 'A'}]
A list can be enlarged with * and a number as shown below:
1D list:
v1 = ['a', 'b', 'c'] * 3
v2 = [0] * 3
print(v1) # ['a', 'b', 'c', 'a', 'b', 'c', 'a', 'b', 'c']
print(v2) # [0, 0, 0]
2D list:
v1 = [['a', 'b', 'c']] * 3
v2 = [[0]] * 3
print(v1) # [['a', 'b', 'c'], ['a', 'b', 'c'], ['a', 'b', 'c']]
print(v2) # [[0], [0], [0]]
3D list:
v1 = [[['a', 'b', 'c']]] * 3
v2 = [[[0]]] * 3
print(v1) # [[['a', 'b', 'c']], [['a', 'b', 'c']], [['a', 'b', 'c']]]
print(v2) # [[[0]], [[0]], [[0]]]
list() can create a list with or without a list, tuple, set, dictionary, iterator, string or range() as shown below:
*Memos:
- The 1st argument is
iterable(Optional-Type:iterable). - Don't use
iterable=.
v = list() # Empty list
print() # []
v = ['a', 'b', 'c', 'd', 'e'] # List
print(list(v)) # ['a', 'b', 'c', 'd', 'e']
v = ('a', 'b', 'c', 'd', 'e') # Tuple
print(list(v)) # ['a', 'b', 'c', 'd', 'e']
v = {'a', 'b', 'c', 'd', 'e'} # Set
print(list(v)) # ['c', 'a', 'd', 'b', 'e']
v = {'name': 'John', 'age': 36, 'gender': 'Male'} # Dictionary
print(list(v))
print(list(v.keys()))
# ['name', 'age', 'gender']
print(list(v.values()))
# ['John', 36, 'Male']
print(list(v.items()))
# [('name', 'John'), ('age', 36), ('gender', 'Male')]
v = iter(['a', 'b', 'c', 'd', 'e']) # Iterator
print(list(v)) # ['a', 'b', 'c', 'd', 'e']
v = 'Hello' # String
print(list(v)) # ['H', 'e', 'l', 'l', 'o']
v = range(5)
print(list(v)) # [0, 1, 2, 3, 4]
A list comprehension can create a list as shown below:
v = [x**2 for x in range(6)]
print(v) # [0, 1, 4, 9, 16, 25]
Be careful, a huge list gets MemoryError as shown below:
v = ['a', 'b', 'c'] * 1000000000
# MemoryError
v = range(100000000)
print(list(v)) # MemoryError
A list can be used with len() to get the length as shown below:
v = ['a', 'b', 'c', 'd', 'e']
print(len(v)) # 5
You can access and change a list by indexing as shown below. *Indexing can be done with one or more [index]:
v = ['a', 'b', 'c', 'd', 'e', 'f', 'g', 'h'] # 1D list
print(v[0], v[1], v[2], v[3], v[4], v[5], v[6], v[7])
print(v[-8], v[-7], v[-6], v[-5], v[-4], v[-3], v[-2], v[-1])
# a b c d e f g h
v[1] = 'B'
v[-7] = 'B'
print(v) # ['a', 'B', 'c', 'd', 'e', 'f', 'g', 'h']
v = [['a', 'b', 'c', 'd'], ['e', 'f', 'g', 'h']] # 2D list
print(v[0], v[1])
print(v[-2], v[-1])
# ['a', 'b', 'c', 'd'] ['e', 'f', 'g', 'h']
print(v[0][0], v[0][1], v[0][2], v[0][3], v[1][0], v[1][1], v[1][2], v[1][3])
print(v[-2][-4], v[-2][-3], v[-2][-2], v[-2][-1],
v[-1][-4], v[-1][-3], v[-1][-2], v[-1][-1])
# a b c d e f g h
v[0][1] = 'B'
v[-2][-3] = 'B'
v[1] = ['E', 'F', 'G', 'H']
v[-1] = ['E', 'F', 'G', 'H']
print(v) # [['a', 'B', 'c', 'd'], ['E', 'F', 'G', 'H']]
v = [[['a', 'b'], ['c', 'd']], [['e', 'f'], ['g', 'h']]] # 3D list
print(v[0], v[1])
print(v[-2], v[-1])
# [['a', 'b'], ['c', 'd']] [['e', 'f'], ['g', 'h']]
print(v[0][0], v[0][1], v[1][0], v[1][1])
print(v[-2][-2], v[-2][-1], v[-1][-2], v[-1][-1])
# ['a', 'b'] ['c', 'd'] ['e', 'f'] ['g', 'h']
print(v[0][0][0], v[0][0][1], v[0][1][0], v[0][1][1], v[1][0][0],
v[1][0][1], v[1][1][0], v[1][1][1])
print(v[-2][-2][-2], v[-2][-2][-1], v[-2][-1][-2], v[-2][-1][-1],
v[-1][-2][-2], v[-1][-2][-1], v[-1][-1][-2], v[-1][-1][-1])
# a b c d e f g h
v[0][0][1] = 'B'
v[-2][-2][-1] = 'B'
v[0][1] = 'C'
v[-2][-1] = 'C'
v[1] = ['D', ['E', 'F']]
v[-1] = ['D', ['E', 'F']]
print(v) # [[['a', 'B'], 'C'], ['D', ['E', 'F']]]
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