Kristian Rother: /* Creating lists from other lists */

2013-02-05T20:07:20Z

Creating lists from other lists

New page

{{Cat|Python Commands}}
{{Python Links}}

== Creating tuples ==
A tuple is a sequence of elements that cannot be modified. They are useful to group elements of different type.

<source lang="python">
t = ('bananas','200g',0.55)
</source>

== Creating lists ==
A list is a sequence of elements that can be modified. In many cases, all elements of a list will have the same type.

<source lang="python">
l = ['apples',
'bananas',
'oranges']
</source>

== Accessing elements of lists and tuples ==
Using square brackets, any element of a list and tuple can be accessed. The first character has the index 0.

<source lang="python">
l = [1,2,3,4]
print l[0] # first
print l[3] # last
print l[-1] # last
l[0] = 'kiwi' # assigning an element
</source>

== Creating lists from other lists ==
Lists can be sliced by applying square bracketsin the same way as substrings.

<source lang="python">
l = [0,1,2,3,4,5]
print l[1:3] # [1,2]
print l[0:2] # [0,1]
print l[:3] # [0,1,2]
print l[-2:] # [4,5]
m = l[:] # creates a copy!
</source>

===== List functions =====

<source lang="python">
l[0] = 'kiwi' # assigning an element
</source>

===== Adding elements to a list: =====
<source lang="python">
l.append(5) # adds at the end
</source>

===== Removing elements from a list: =====
<source lang="python">
l.remove(3)

l.pop() # removes last element
</source>

===== Sorting a list =====
<source lang="python">
l.sort()
</source>

===== Count elements: =====
<source lang="python">
l.count(3)
</source>

Tuples and Lists - Revision history

Kristian Rother: /* Creating lists from other lists */