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CS 3723
Programming Languages |
Containers
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Reference links given below will be to the online book:
Building skills in Python
3. Containers: Strings, Lists, Tuples,
Dictionaries, Sets:
The items in each of these structures except for Sets can be accessed using an
index in square brackets: [ ]. For the first three this can
be an integer from 0 to the length (the function
len)
of the container minus 1.
Especially the first three: Strings, Lists, and Tuples have a
great deal in common. This commonality is explained very well in:
Sequences: Strings, Tuples and Lists.
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Containers |
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| Name |
Item |
Enclosed In |
Access |
Concat |
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String | char | Quote marks
a='abc', or
a="abc", | a[0],
a[1], ... | Yes, + |
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List | any | Brackets
b=[ a, 'b', 2,
[x, y], 4.5] | b[0],
b[1], ... |
Yes, + |
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Tuple | any | Parentheses
c=( a, 'b', 2,
[x, y], 4.5) | c[0],
c[1], ... |
Not
allowed |
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Dictionary | Keyed
Pair |
Braces
d={ 'a':14, 'b':23
'c':56 } | if 'a' in d
p=d['a'] | d.update(m) |
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Set | any | e=set([3,5,7,11,
13,17,19]) | in | Ops: | &
- ^ |
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3.1. Strings:
Strings are very similar to those in other languages.
Of course lots of string methods.
String can be enclosed in single, double or triple quotes.
See
Strings.
3.2. Lists:
These are very similar to arrays in a normal language, except that
the items in these lists can be anything, including other lists
or functions.
See
Lists.
3.3. Tuples:
Similar to lists, except that they are immutable: once created
they can't be changed. The main reason to use these appears to
be saving storage. One book says that Python programmers
often just use a list where a tuple would do. See
Tuples.
3.4. Dictionaries:
These are a familiar feature in Perl and other scripting languages,
called "hashes" or "associative arrays" in Perl. See
Dictionaries.
3.5. Sets :
I see how these sets work, and how one can manipulate them.
Sets are an unusual
feature in a programming language. Not sure how useful they might be.
See
Sets.
(Revision date: 2014-05-24.
Please use ISO 8601,
the International Standard.)
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