Data Types in Python

When discussing data types in Python, we must start with the standard data types. The standard data types in Python are as follows:

Numeric Types:

Numeric data types are used to store numerical values.

They are immutable data types, meaning that changing a numeric data type will allocate a new object.

In Python 2.X, there are more data types, including int (signed integer), long (long integer [which can also represent octal and hexadecimal]), float (floating-point), and complex (complex numbers).

In Python 3.X, the long type has been removed and replaced with int, with the most commonly used types being int or float.

Strings:

Strings are represented by the string type and consist of a sequence of characters that can include numbers, letters, and underscores.

In Python, strings are enclosed in quotes, which can be: single quotes (‘ ‘), double quotes (” “), or triple quotes (”’ ”’), and there are two indexing methods:

Left to right indexing starts at 0, with the maximum value being the length of the string minus 1.

Right to left indexing starts at -1, with the maximum value at the beginning of the string.

Indexing is represented with [ ], for example, if we define str=RUNOOB, to get the N value, the expression would be: str[2] or str[-4].

For string operations, there are the following methods:

str = ‘Hello World!‘

print(str ) # Outputs the complete string

print(str[0]) # Outputs the first character in the string

print(str[2:5]) # Outputs the substring from the third to the sixth character

print(str[2:]) # Outputs the substring starting from the third character

print(str*2) # Outputs the string twice

print(str+“TEST“) # Outputs the concatenated string

Lists:

Lists are represented by [ ], and are one of the most frequently used data types in Python, as well as the most general collection data type.

In addition to indexing, slicing operations can also be performed:

For example:

list = [ ‘runoob‘, 786 , 2.23, ‘john‘, 70.2 ]

tinylist = [123, ‘john‘]

print(list) # Outputs the complete list

print(list[0]) # Outputs the first element of the list

print(list[1:3]) # Outputs the second to third elements

print(list[2:]) # Outputs all elements from the third to the end of the list

print(tinylist*2) # Outputs the list twice

print(list+tinylist) # Prints the combined list

Tuples:

Tuples are similar to lists, but unlike lists, tuples are represented by ( ) and their elements are separated by commas. Tuples cannot be modified, only read. To delete, the entire tuple must be deleted, and operations are not as flexible as lists.

For example:

tuple = ( ‘runoob‘, 786 , 2.23, ‘john‘, 70.2 )

tinytuple = (123, ‘john‘)

print(tuple) # Outputs the complete tuple

print(tuple[0]) # Outputs the first element of the tuple

print(tuple[1:3]) # Outputs the second to fourth (not including) elements

print(tuple[2:]) # Outputs all elements from the third to the end of the tuple

print(tinytuple*2) # Outputs the tuple twice

print(tuple+tinytuple) # Prints the combined tuple

Dictionaries:

Dictionaries are the most flexible data type in Python, aside from lists. The difference between dictionaries and lists is that elements in a dictionary are accessed by keys, not by offsets. Dictionaries are represented by { }, with each element consisting of a key and a value. Keys cannot be duplicated, while values can be duplicated.

For example:

dict = {}

dict[‘one‘] = “This is one“

dict[2] = “This is two“