Python Learning-Sequence Basics

The sequence is the most basic data structure in Python. Each element in the sequence is assigned a number-its position, or index, the first index is 0, the second index is 1, and so on.

The main sequences used are tuples and lists.

Define a list first

names=["QCG", "Dajiangjun", "Nana", "Jiantao", "Pangpang"]

First, select the elements in the list

1, through the index, the index at a time starting from 0, the first is 0, the second is 1, one analogy; from the back number, the last one is-1, the second to the bottom is-2

Names[0]=qcg

names[2]= Jiantao

NAME[-1] =pangpang

2. Selecting elements through slices

names[0:2]==["QCG", "Dajiangjun"]

names[0:3:2]==["QCG", "Nana"] from 0 to 3, step 2, that is, take one element at a intervals.

Names[-1:-2]=[] #因为是从前往后数,-no element after 1, so the return is empty.

Names[-2:-1] =["Jiantao"]

List operations: Adding and deleting changes

1, increase

Append method:

>>> LST = ["A", "B", "C"] append element
>>> lst.append ("D")
>>> Print (LST)
[' A ', ' B ', ' C ', ' d ']

Insert inserts elements by index

>>> Lst.insert (3, "QCG")
>>> Print (LST)
[' A ', ' B ', ' C ', ' QCG ', ' d ']
>>>

Extend appends multiple values of another list to one list at a time:

>>> LST
[' A ', ' B ', ' C ', ' QCG ', ' d ']
>>> lst2=[2,3,4]
>>> Lst.extend (LST2)
>>> Print (LST)
[' A ', ' B ', ' C ', ' QCG ', ' d ', 2, 3, 4]

>>> LST
[' A ', ' B ', ' C ', ' QCG ', ' d ', ' t ']

>>> lst.extend (Lst2[0:2])
>>> LST
[' A ', ' B ', ' C ', ' QCG ', ' d ', ' t ', 2, 3]

Second, delete

Not to be continued

Python Learning-Sequence Basics