In my previous refreshers, which you can access from the series navigation links at the top of this article, I talked about two important Python concepts you need to grasp in order to move forward in your Python learning journey.
This tutorial is a continuation of the Python refresher series, and today I will be talking about Tuples. That way, you will have three important concepts in your pocket and will be ready to dig deeper in the Python language.
So, let's go ahead and move directly to this interesting topic of Tuples.
What About Tuples?
If you understood Lists, Tuples will be very simple to grasp, because they are similar to Lists except for two main differences:
- Tuples are immutable, so once you create a Tuple, you cannot change its content or even its size, unless you make a copy of that Tuple.
- They are written in parentheses
( )rather than in square brackets
Thus, as you can guess, Tuples consist of a set of ordered objects which can be of any type (i.e. Strings, Lists, Dictionaries, Tuples, etc.), and are accessed by an index (offset), as opposed to Dictionaries where items are accessed by key. It is important to note here that Tuples store references to the objects they contain.
Before moving to some Tuple operations, let's see what a simple Tuple looks like:
tup = (1)
This is a simple Tuple that contains one item, an integer value. The output of this Tuple will be
Another example of a Tuple with three items of different object types is as follows:
tup = (31,'abder',4.0)
The output for the above statement is:
(31, 'abder', 4.0)
You can even write the above Tuple without parentheses as follows:
tup = 31,'abder',4.0
Very flexible, isn't it?
As a final example, let's see how a nested Tuple would look:
nested_tuple = ('ID', ('abder', 1234))
Let's now walk through some Tuple operations.
Concatenation is the combination of Tuples together. Say that we have the following two Tuples:
tuple1 = (1,2,3,4,5)
tuple2 = (6,7,8,9,10)
In order to concatenate
tuple2, we simply type:
tup = tuple1 + tuple2
Notice that we used the
+ operator to perform the concatenation. This will result in the following output:
(1, 2, 3, 4, 5, 6, 7, 8, 9, 10)
Tuple repetition is simply carried out using the
* operator. If we want to repeat
tuple1 three times, we do the following:
tuple1 * 3
The result of this statement is:
(1, 2, 3, 4, 5, 1, 2, 3, 4, 5, 1, 2, 3, 4, 5)
To check the membership of some item in the Tuple, we use
in, as follows:
7 in tuple1
This will return
7 doesn't belong to
In order to indicate where some item is located in the Tuple, we use
index. For instance, if we want to find the location of the item
tuple1, we do the following:
In this case, the return value will be
4, which is the location of the item
A nice operation in Tuples is counting the number of times an element exists in the Tuple. Say we have the following Tuple:
tuple3 = (65,67,5,67,34,76,67,231,98,67)
If we want to see how many times
67 exists in
tuple3, we simply do the following:
The result for this statement should be
Indexing is the process of accessing a Tuple element by index (subscript). If we want to access the fifth index in
tuple3, we do the following:
which will return
An index can also be negative, that is, counting will start from the right of the Tuple. Thus, the result of
tuples3[-6] will be
34, provided that the range of the negative indices in
What if you chose an index out of this range? Like
tuples3[-11] for instance? This is what you would get in this case:
Traceback (most recent call last):
File "tuple.py", line 2, in <module>
IndexError: tuple index out of range
Notice that negative indices start from
-1. So, if you typed the index as
-0, this is the same as the index
tuples3[-0] will return
Unlike indexing, which provides us with one element as a result, slicing provides us with a sequence of elements. An example of slicing is the following statement:
The output of this statement might seem confusing at the beginning:
(5, 67, 34)
76 is not included, although in reality it is in index
5. This is because in slicing the
start index is always included, and the
end index is excluded, that is,
end - 1.
Another example of Tuples is as follows:
The output of the statement would be as follows:
(65, 67, 5, 67)
Now, this is a small quiz for you. What is the output of the following statement?
You can find more information on Tuples from Python's documentation. As you might notice, although Tuples work similarly to Lists, they don't have as many methods as lists, since Tuples, as mentioned above, are immutable—that is, the contents of the Tuple cannot be changed.
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