002-5. Detail of list
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# We can use list for data source in "for" iteration statement
b = [1,2,3,4,5]
for i in b:
print(i, end=' ')
# Task which "range()"" can do but which "b" can't do is
# that when using "b" we should use "entire b"
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# Type of range() and type of list are different
# It's not recommended to use both of them at the same time
b = [1,2]
print(type(range(5)), type(b))
# output:
# <class 'range'> <class 'list'>
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# The common point of range() and list is that they contains multiple values
# So, we call them iterable
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# In Python, we process resersing task by using reversed()
for i in reversed(b):
print(i, end=' ')
print()
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for i in reversed(range(len(b))):
print(b[i], end=' ')
print()
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# We can use enumerate() to print both data and its index
# as tuple data type
for i in enumerate(b):
print(b[i], end=' ')
print()
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# We can remove parenthesis when displaying
for i in enumerate(b):
print(i,i[0],i[1], end=' ')
print()
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# tuple is constant version of list
# The way of using tuple is same with the way of using list
# The only difference with list is that we can't change elements inside of tuple
t = (1,2,3)
# This makes error
t[0]=99
print(t)
# We don't use tuple too much compared to list
# The most used tuple case are 2
# 1. When you pass argument into method's parameter
# 1. When you return return value from method
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t1, t2 = 1, 2
print(t1, t2)
# output:
# 1 2
# t3 takes 1, 2 as tuple data type
t3 = 1, 2
print(t3)
# output:
# (1, 2)
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# I can combine enumerate() and tuple
b = [1,2,3]
for i, v in enumerate(b):
print(i, v)
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a = range(0,10,2)
print(a)
# output:
# range(0,10,2)
a = list(range(0,10,2))
print(a)
# output:
# [0,2,4,6,8]
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a = list(range(0,10,2))
b = a
a[0] = 99
print(a)
# output:
# [99,2,4,6,8]
print(b)
# output:
# [99,2,4,6,8]
# We can determine a and b use same object
# This is shallow copy
# This is default way
# This is called "call by reference"
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a = list(range(0,10,2))
b = a.copy()
a[0] = 99
print(a)
# output:
# [99,2,4,6,8]
print(b)
# output:
# [0,2,4,6,8]
# We can determine a and b use different object
# This is deep copy
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a = [99,2,4,6,8]
print(a[0])
# output:
# 99
print(a[-1], a[len(a)-1])
# output:
# 8
print(a[-2])
# output:
# 6
print(-len(a))
# output:
# 99
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