List consist of a sequnece of different types delimited by square barckets [ and ]
Unlike strings which only contain characters, list elements can be anything, including other lists
In [1]: alist=['The','principal','author','of','Python','is',['Guido','van','Rossum']]
In [2]: alist[6]
Out[2]: ['Guido', 'van', 'Rossum']
In [3]: alist[6][0]
Out[3]: 'Guido'
lists are mutable and strings are immutable
In [4]: alist[1]='first'
In [5]: alist
Out[5]: ['The', 'first', 'author', 'of', 'Python', 'is', ['Guido', 'van', 'Rossum']]
In [6]: astring="Van Rossum is a big fan of Monty Python's Flying Circus"
In [7]: astring[1]='x'
---------------------------------------------------------------------------
TypeError Traceback (most recent call last)
/net/rowley/ifs/data/bcc/duan/test_python/<ipython-input-7-7abb36ddd2dd> in <module>()
----> 1 astring[1]='x'
TypeError: 'str' object does not support item assignment
We can grow lists in several ways - using insert, append and list concatenation
In [8]: blist=['Python','was','conceived','in','1989']
In [9]: blist
Out[9]: ['Python', 'was', 'conceived', 'in', '1989']
In [10]: blist.append('around Christmas')
In [11]: blist
Out[11]: ['Python', 'was', 'conceived', 'in', '1989', 'around Christmas']
In [12]: blist=blist+["as","a","hobby","project"]
In [13]: blist
Out[13]:
['Python',
'was',
'conceived',
'in',
'1989',
'around Christmas',
'as',
'a',
'hobby',
'project']
In [14]: blist[4:4]=["December",]
In [15]: blist
Out[15]:
['Python',
'was',
'conceived',
'in',
'December',
'1989',
'around Christmas',
'as',
'a',
'hobby',
'project']
We can remove items from a list by using pop, del or assigning a slice to the empty list
In [16]: blist.pop()
Out[16]: 'project'
In [17]: blist
Out[17]:
['Python',
'was',
'conceived',
'in',
'December',
'1989',
'around Christmas',
'as',
'a',
'hobby']
In [18]: del blist[4]
In [19]: blist
Out[19]:
['Python',
'was',
'conceived',
'in',
'1989',
'around Christmas',
'as',
'a',
'hobby']
In [20]: del blist[6:9]
In [21]: blist
Out[21]: ['Python', 'was', 'conceived', 'in', '1989', 'around Christmas']
In [22]: blist[3:5]=[]
In [22]: blist
Out[22]: ['Python', 'was', 'conceived', 'around Christmas']
