List Manipulation In Python
Operation On LISTS
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1. Concatenation (+)
2. Repetition(*)
3. Membership Testing(in/not in)
4. Indexing -[]
5. Slicing - [start:stop:step]
1.Concatenation : (addition)
For example:
l1=[‘Red’,’Green’]
l2=[10,20,30]
>>> l1=['red','blue']
>>> l2=[10,20,30]
>>> l3=l1+['yellow']
>>> l3
['red', 'blue', 'yellow']
>>> l1
['red', 'blue']
>>> l3
['red', 'blue', 'yellow']
>>> l4=l1+l2
>>> l4
['red', 'blue', 10, 20, 30]
>>> l5=['Green','white']+['Black']
>>> l5
['Green', 'white', 'Black']
>>> l1=l2+40
Traceback (most recent call last):
File "<pyshell#19>", line 1, in <module
l1=l2+40
TypeError: can only concatenate list (not "int") to list
>>> l1=l2+'python'
Traceback (most recent call last)
File "<pyshell#20>", line 1, in <module>
l1=l2+'python'
TypeError: can only concatenate list (not "str") to list
>>>
2.Repetition/Replication(*)
Multiply (* asterisk) operators replicates the list for a specifies number of times and creates a new list.
For example
>>> list1=[10,20,30]
>>> list1*2
[10, 20, 30, 10, 20, 30]
>>> list1*3
[10, 20, 30, 10, 20, 30, 10, 20, 30]
>>> list1*4
[10, 20, 30, 10, 20, 30, 10, 20, 30, 10, 20, 30]
>>> x='python'*3
>>> x
'pythonpythonpython'
>>>
3.Membership Operators:
Membership testing is an operation carried out to check or test whether a particular elements /items is a member of that sequence or not.
For Example:
>>> x=[10,20,30,40,50,100]
>>> print(100 in x)
True
>>> print(100 not in x)
False
>>> print(12 not in x)
True
>>>
4.Indexing:
Index is nothing but there is an index values for each item present in the sequence.
>>> x=[10,20,30,40,50,100]
>>> x[0]
10
>>> x[-1]
100
>>> x[4]
50
>>>
5.Slicing:
>>> x=[1,2,3,4,5,6]
>>> x[0:3]
[1, 2, 3]
>>> x[0:5]
[1, 2, 3, 4, 5]
>>> x[1:5]
[2, 3, 4, 5]
>>> x[1:5:-1]
[]
>>> x[0:5:-1]
[]
>>> x[1:3:2]
[2]
>>> x[0:5:2]
[1, 3, 5]
>>> x[0:5:-1]
[]
>>>
Nested List:
For example:
>>> x=[1,2,3,[10,20,30,40],'a','b']
>>> x[4]
'a'
>>> x[3]
[10, 20, 30, 40]
>>> x[3][1]
20
>>>
Coping List:
Method 1:
L1=L2
Method 2:
L3=L1[:]
Method 3:
L4=list(L3)
Method 4:
L5=L4.copy()
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