Summary for python learning: Positive/Negative Indexes, Slicing:
Lists, strings, and tuples have a positive index system:
["Mon", "Tue", "Wed", "Thu", "Fri", "Sat", "Sun"]
0 1 2 3 4 5 6
And a negative index system:
["Mon", "Tue", "Wed", "Thu", "Fri", "Sat", "Sun"]
-7 -6 -5 -4 -3 -2 -1
In a list, the 2nd, 3rd, and 4th items can be accessed with:
days = ["Mon", "Tue", "Wed", "Thu", "Fri", "Sat", "Sun"]
days[1:4]
Output: ['Tue', 'Wed', 'Thu']
First three items of a list:
days = ["Mon", "Tue", "Wed", "Thu", "Fri", "Sat", "Sun"]
days[:3]
Output:['Mon', 'Tue', 'Wed']
Last three items of a list:
days = ["Mon", "Tue", "Wed", "Thu", "Fri", "Sat", "Sun"]
days[-3:]
Output: ['Fri', 'Sat', 'Sun']
Everything but the last:
days = ["Mon", "Tue", "Wed", "Thu", "Fri", "Sat", "Sun"]
days[:-1]
Output: ['Mon', 'Tue', 'Wed', 'Thu', 'Fri', 'Sat']
Everything but the last two:
days = ["Mon", "Tue", "Wed", "Thu", "Fri", "Sat", "Sun"]
days[:-2]
Output: ['Mon', 'Tue', 'Wed', 'Thu', 'Fri']
A single in a dictionary can be accessed using its key:
phone_numbers = {"John Smith":"+37682929928","Marry Simpons":"+423998200919"}
phone_numbers["Marry Simpsons"]
Output: '+423998200919'
