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Python tuple

The tuple data structure is used to store a group of data.  The elements in this group are separated by a comma. Once created, the values of a tuple cannot change.  

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Python Tuple


An empty tuple in Python would be defined as:

tuple = ()

A comma is required for a tuple with one item:

tuple = (3,)

The comma for one item may be counter intuitive,  but without the comma for a single item, you cannot access the element.  For multiple items, you do not have to put a comma at the end.  This set is an example:

personInfo = ("Diana", 32, "New York")

The data inside a tuple can be of one or more data types such as text and numbers.

Data access


To access the data we can simply use an index. As usual, an index is a number between brackets:

#!/usr/bin/env python

personInfo = ("Diana", 32, "New York")
print(personInfo[0])
print(personInfo[1])

If you want to assign multiple variables at once, you can use tuples:

#!/usr/bin/env python

name,age,country,career = ('Diana',32,'Canada','CompSci')
print(country)

On the right side the tuple is written. Left of the operator  equality operator are the corresponding output variables.

Append to a tuple in Python


If you have an existing tuple, you can append to it with the + operator.  You can only append a tuple to an existing tuple.

#!/usr/bin/env python

x = (3,4,5,6)
x = x + (1,2,3)
print(x)

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Leave a Reply:




Lee Sun, 07 Jun 2015

Why would you use a Tuple over a List? What's the difference?

Frank Sun, 07 Jun 2015

Tuple is another datastructure, it has different properties. A tuple has no methods and cannot be changed once created. Tuples may be faster than lists to iterate.

Leasinop Sun, 07 Jun 2015

I also read that tuples are heterogeneous (could be used for various data types) while lists are homogeneous (should be used for one data type)

Pradeep Kaja Fri, 19 Jun 2015

I do not use this wording of Heterogeneous/Homogeneous. Its very confusion, because we can insert values of different data types in both list and tuple. I believe the only difference is that List is mutable Tuple is not. Tuple is fast accessed on memory when compared to List in some cases.

Reddy Fri, 26 Jun 2015

list are homogeneous.. ??? l= ["a","b","c"]; l.append("d"); l.append(123); I added a string type and an integer type. Both worked fine.

Frank Fri, 26 Jun 2015

Hi Reddy, a python list can hold multiple datatypes:

#!/usr/bin/env python

l= ["a","b","c"];
l.append("d");
l.append(123);

print(l)

# print datatype
for item in l:
print(type(item))

Output:

['a', 'b', 'c', 'd', 123]
<class 'str'="">
<class 'str'="">
<class 'str'="">
<class 'str'="">
<class 'int'="">
Lim Thu, 20 Aug 2015

why we have to use tuple? it seems all tuple's usage also can be achieved by list.

Frank Thu, 20 Aug 2015

Lists are dynamic in size while tuples are fixed. You can't add or remove elements to a tuple. Tuples are faster than lists. They secure from data being modified.

Lei Wed, 25 Nov 2015

person = ('Diana','Canada','CompSci')
s = ''.join(person)
print(s)

i can,t understand

Frank Thu, 26 Nov 2015

First line is a tuple (pair of variables). Then a string is created and printed.

Vaishnavi Tue, 08 Dec 2015

How does Join work ?
When I give -

   person = ('Diana','Canada','CompSci' )
s = '-trial '.join(person)
print(s)

, the output is " Diana-trial Canada-trial CompSci" . The join does not happen for the last value.

Frank Tue, 08 Dec 2015

Hi vaishnavi, I'll look at this asap.

Frank Thu, 10 Dec 2015

str.join(iterable)
Join returns a string which is the concatenation of the strings in the iterable iterable. The separator between elements is the string providing this method.
In this case we have concatenations (Diana, Canada) and(Canada, CompSci). They are connected with the separator.

To add the text '-trial' to each element, simply use a loop on the list with a concatenation.

Vaishnavi Thu, 07 Jan 2016

Hi Frank, thanks a lot for your reply..!
[ Sorry for the late reply ..]
I understood why it is not added at the end. But how do we achieve this using a loop.
Is the below code correct ?

person = ('Diana', 'Canada', 'CompSci' )
for i in range (len(person)):
s = '-trial'.join(person)
print (s)


Output: Diana-trialCanada-trialCompSci
Even here the concatenation does not happen for the last one .

Frank Fri, 08 Jan 2016

You could do this:

s = ""
person = ('Diana', 'Canada', 'CompSci' )
for i in range (len(person)):
s = s + person[i] + "-trial "
print (s)


which outputs:
Diana-trial Canada-trial CompSci-trial

Vaishnavi Sat, 09 Jan 2016

Thanks Frank, it works.
Also thanks for such a wonderful tutorial !!

Reeba Thu, 28 Jan 2016

but we can Append to a tuple in Python,which will change its size.so how can we say that its size is fixed

Frank Thu, 28 Jan 2016

Hi Reeba, technically we are not appending but creating a new tuple that replaces the old one. In the example above we say "x = " which recreates a new tuple. In practice this is of course appending, but technically on the computational level we are replacing the memory.

Reeba Tue, 02 Feb 2016

Thanks Frank !!!