Python Data Types

Everything is an object in Python programming. Data types are actually classes, and variables are instance (object) of these classes.

Python has six standard Data Types:

• Numbers
• String
• List
• Tuple
• Set
• Dictionary

Python Data Type – Numeric

Python numeric data type is used to hold numeric values like

• int – Integers can be of any length, it is only limited by the memory available.
• float- holds floating precision numbers and it’s accurate upto 15 decimal places.

Input

var1 = 5
var2 = 5.0
print(var1, "is of type",type(var1))
print(var2, "is of type",type(var2))

Output

5 is of type &lt class 'int' &gt
5.0 is of type &lt class 'float' &gt

Input

varfloat = 0.1234567890123456789
print(varfloat, "is of type", type(varfloat))
print(varfloat)

Output

0.12345678901234568 is of type &lt class 'float'&gt
0.12345678901234568

• complex- holds complex numbers. – An complex number is represented by “x + yi”. Python convert the real number x and y into complex using the funxtion complex(x+y). The real part can be accessed using the function real() and imaginary part can be represented by imag().

Input

var3 = 1+2j
print(var3, "is complex number?", isinstance(1+2j,complex))
print(var3, "is of type",type(var3))

Output

(1+2j) is complex number? True
(1+2j) is of type &lt class 'complex'&gt

These are defined as int, float and complex class in python.

In Python we need not to declare datatype while declaring a variable like C or C++. We can simply just assign values in a variable. But if we want to see what type of numerical value is it holding right now, we can use type(), like this:

Python Data Type – String

The string is a sequence of characters. Python supports Unicode characters. Generally, strings are represented by either single or double quotes. And triple quotes for multi line

Input

String1 = 'This is a String in single quote'
String2 = "This is a String in double quote"
String3 = '''This is a
string in triple quote'''

print('Single quote---', String1)
print('Double quote---', String2)
print('Triple quote/Multi line---', String3)

Output

Single quote--- This is a String in single quote
Double quote--- This is a String in double quote
Triple quote/Multi line--- This is a string in triple quote

Python Data Type – List

List is an ordered sequence of items. It is one of the most used datatypes in Python and is very flexible. All the items in a list do not need to be of the same type.

Declaring a list is pretty straight forward. Items separated by commas are enclosed within brackets [ ].

Input

varlist = [1, 5.3, 'Python']

print(varlist, "is of type", type(varlist))
print(varlist)

Output

[1, 5.3, 'Python'] is of type &lt class 'list' &gt
[1, 5.3, 'Python']

We can use the slicing operator [ ] to extract an item or a range of items from a list. Index starts form 0 in Python.

Input

varlist = [5,10,15,20,25,30,35,40]
# varlist[2] = 15
print("varlist[2] = ", varlist[2])
# varlist[0:3] = [5, 10, 15]
print("varlist[0:3] = ", varlist[0:3])
# varlist[5:] = [30, 35, 40]
print("varlist[5:] = ", varlist[5:])

Output

varlist[2] = 15
varlist[0:3] = [5, 10, 15]
varlist[5:] = [30, 35, 40]

List is mutable. That means data in a List is updateable.

Input

varlist[1] = 100
varlist[5] = 300

print(varlist)

Output

[5, 100, 15, 20, 25, 300, 35, 40]

Python Data Type – Tuple

Tuple is another data type which is a sequence of data similar to list. But it is immutable. That means data in a tuple is write protected. Data in a tuple is written using parenthesis () and commas (,). It is also an ordered sequence of item same as list.

Input

varTuple = (1, 5.3, 'Python')
print(varTuple, "is of type", type(varTuple))
print(varTuple)

Output

(1, 5.3, 'Python') is of type &lt class 'tuple' &gt
(1, 5.3, 'Python')

We can use the slicing operator [] to extract items but we cannot change its value.

Input

varTuple = (5,10,15,20,25,30,35,40)

# varlist[2] = 15
print("varTuple[2] = ", varTuple[2])

# varlist[0:3] = [5, 10, 15]
print("varTuple[0:3] = ", varTuple[0:3])

# varlist[5:] = [30, 35, 40]
print("varTuple[5:] = ", varTuple[5:])

Output

varTuple[2] = 15
varTuple[0:3] = (5, 10, 15)
varTuple[5:] = (30, 35, 40)

Tuple it is immutable. That means data in a tuple is write protected

Input

varTuple[1] = 100
varTuple[5] = 300

print(varTuple)

Output

TypeError Traceback (most recent call last)
in
----> 1 varTuple[1] = 100
2 varTuple[5] = 300
3 print(varTuple)
TypeError: 'tuple' object does not support item assignment

Python Data Type – Set

Set is an unordered collection of unique items.
Set is defined by values separated by comma inside braces { }.
Items in a set are not ordered.
Set objects does not support indexid.

Input

varSet = {5,2,3,1,4}

print(varSet, "is of type", type(varSet))
print(varSet)

Output

{1, 2, 3, 4, 5} is of type &lt class 'set' &gt
{1, 2, 3, 4, 5}

We can perform set operation like union, intersection on two sets. Set have unique values. They eliminate duplicates.

Input

varSet = {5,2,3,1,4,1,2,3,4}
print(varSet)

Output

{1, 2, 3, 4, 5}

Since, set are unordered collection, indexing has no meaning. Hence the slicing operator [] does not work.

Input

varSet[1]

Output

TypeError Traceback (most recent call last)
in
----> 1 varSet[1]

TypeError: 'set' object is not subscriptable

Python Data Type – Dictionary

Python Dictionary is also an unordered sequence of data of key-value pair form.
It is similar to the hash table type.
Dictionaries are written within curly braces { } in the form key:value. Key and Value can be any type.
It is very useful to retrieve data in an optimized way among a large amount of data.

Input

vardict = {
"brand": "Ford",
"model": "Mustang",
"year": 1964
}

print(vardict, "is of type", type(vardict))
print(vardict)

Output

{'brand': 'Ford', 'model': 'Mustang', 'year': 1964} is of type
{'brand': 'Ford', 'model': 'Mustang', 'year': 1964}

You can access the items of a dictionary by referring to its key name, inside square brackets: And also using Get() function.

Input

print(vardict["model"])
print(vardict.get("model"))

Output

Mustang
Mustang