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<h3>
Data Structures</h3>
<p>Python implements a variety of data structures, such as lists, tuples, ranges, and dictionaries (also known as <tT CLAss="monofont">hash tables</tt>).</P>
<H4>
Lists</H4>
<P>Lists are mutable sequences of objects indexed by natural numbers that can be changed after they are created.</p>
<p>Lists are very flexible and easy to create. They are always enclosed in brackets:</p>
<pRE>
>>> lst = [1,2,3,4] # this is simple list
</PRe>
<p>A list can have elements of different data types:</p>
<pre>
>>> lst = [1, "ni!", 2]
</pre>
<p>Lists can also include other lists:</p>
<pre>
>>> lst = [1, "ni!", [1,2,"Albatross!!"]]
</pre>
<p>A list uses the same <a nAme="idx1073742414"></A>operators that <tt cLass="monofont">strings</tT> use. For example, you need to use slice notation to grab a range of elements from a list.</p>
<prE>
>>> lst = [1, "ni!", [1, 2, 3, 4, "Albatross!!", 3]]
>>> lst[1]
"ni!"
</PRE>
<p>To grab elements from lists that are located inside other lists, you need to use a pair of brackets to represent each list. Check out the next couple of examples.</p>
<prE>
>>> lst = [1, "ni!", [1, 2, 3, 4, "Albatross!!", 3]]
>>> lst[2][4]
"Albatross!!"
>>> lst[2][4][5]
"r"
</PRE>
<p>Let's see some examples of operations that can be applied to a list.<a naME="idx1073742415"></A>
<A name="idx1073742416"></A>
<A NAme="idx1073742417"></a>
</p>
<h5>Identifying an Entry</h5>
<pre>
>>> lst = ["p", "a", "r", "r", "o", "t"]
>>> lst.index("o")
4
</pre>
<h5>Assigning Values to a List</h5>
<pre>
>>> lst = ["p", "a", "r", "r", "o", "t"]
>>> lst[1] = "aaaaaaaaaaaaa"
>>> lst
["p", "aaaaaaaaaaaaa", "r", "r", "o", "t"]
</pre>
<H5>Assigning Values to a Slice</h5>
<pRe>
>>> lst = ["p", "a", "r", "r", "o", "t"]
>>> lst[1:4] = ["aaaaaaaaaaaaa", "rrr", "rrrr"]
>>> lst
["p", "aaaaaaaaaaaaa", "rrr", "rrrr", "o", "t"]
</prE>
<h5>Inserting Values</h5>
<p>The following example starts inserting values at index number <tT claSS="monofont">6.</TT>
</p>
<pre>
>>> lst = ["p", "a", "r", "r", "o", "t"]
>>> lst[6:] = [" ", "s", "k", "e", "t", "c", "h"]
['p', 'a', 'r', 'r', 'o', 't', '', 's', 'k', 'e', 't', 'c', 'h']
</PRE>
<P>If the list was longer than 6 elements, the statement would overwrite a portion of the list. Note that you can also insert a value in this list with</p>
<pre>
>>> lst.insert(6, val)
</PRE>
<H5>Deleting a Value</h5>
<pre>
>>> lst = ["p", "a", "r", "r", "o", "t"]
>>> del lst[-1]
>>> lst
["p", "a", "r", "r", "o"]
>>> del lst[0:2]
["r", "r", "o"]
</PRE>
<P>The following example converts objects to their string representation:<a name="idx1073742418"></a>
<a name="idx1073742419"></a>
<a name="idx1073742420"></a>
</p>
<pRe>
>>> lst = [10,20,30,"inquisition","lumberjack"]
>>> text = ""
>>> for element in lst:
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