#### Let’s learn about the python range function in detail.

### Range:

The

rangetype represents an immutable sequence of numbers and is commonly used for looping a specific number of times inforloops.

range(stop) range(start,stop,step)

The value of the **start
**

*start*parameter (or

`0`

if the parameter was not supplied)

The value of the **stop
**

*stop*parameter

The value of the **step
**

*step*parameter (or

`1`

if the parameter was not supplied).If the step is 0, it will raise

**ValueError.**

The arguments to the range function should be integers. (either built-in `int`

or any object that implements the `__index__`

special method)

**Example 1:Only the stop parameter is given.**

`range(10)`

**start**by default will be**0**and**step**by default will be**1**`stop`

is given as**10**.- stop value is excluded. It generates value until 9 only.
- It will return a range object containing numbers starting from
**0 to 9**. - We can convert the range object to list using
**list()**constructor. - We can also iterate using
**for loop**

r=range(10) print (r)#Output:range(0, 10)print (type(r))#Output:<class 'range'>print (list(r))#Output:[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]

**Example 2:Only the start and stop parameter is given.**

**range(1,10)**

**step**by default will be**1**- It will generate a sequence of numbers starting from
**1 to 9**.

r=range(1,10) print (r)#Output:range(1, 10) #Converting range object to listprint (list(r))#Output:[1, 2, 3, 4, 5, 6, 7, 8, 9]

**Example 3:start, stop and step parameter is given**

`range(1,10,2)`

- It will generate a sequence from
**1**, increment by**2**, and will stop at**9**.

r=range(1,10,2) print (r)#Output:range(1, 10, 2) #Converting range object to listprint (list(r))#Output:[1, 3, 5, 7, 9]

**Example 4:We can also decrement step by mentioning a negative number.**

`range(10,1,-2)`

- It will generate a sequence of numbers from
**10**, decrement by**2**, and stop at**1**. - Iterating through range object using
**for loop**.

r=range(10,1,-2) print (r)#Output:range(10, 1, -2)foriinr: print (i)'''Output 10 8 6 4 2 '''

**Example 5:**

r=range(0) print (r)#Output:range(0,0)print (list(r))#Output:[]r1=range(2,2) print (list(r1))#Output:[]

**Example 6: step is given as 0. It will raise ValueError.**

r=range(1,10,0) print (r)#Output:ValueError: range() arg 3 must not be zero

**Example 7: start, stop, and step can be negative numbers also.**

r=range(-10,-20,-2) print (list(r))#Output:[-10, -12, -14, -16, -18]

**Example 8: start, stop, and step is given as variables a,b,c.**

a=1 b=5 c=2 r=range(a,b,c) print (list(r))#Output:[1, 3]

**Example 9: range() function doesn’t support float numbers.It will raise TypeError.**

r=range(2.0,10.0,2)#Output:TypeError: 'float' object cannot be interpreted as an integer

#### Common Sequence Operations on range object:

- Membership test
- Indexing
- Slicing
- len()
- min()
- max()
- index()

#### 1. Membership Test

Membership test can be done by using` in`

and `not in`

operator.

x in s-`True`

if an item of *s* is equal to *x*, else `False`

x not in s-`False`

if an item of *s* is equal to *x*, else `True`

**Example:**

a1=range(5) print (3ina1)#Output:Trueprint (5not ina1)#Output:True

**2.Indexing**

Indexing also supported in **range** objects.

Indexing starts from `0`

. Index` 0`

represents the first element in the sequence.

Negative indexing starts from -1. Index `-1`

represents the last element in the sequence.

r=range(2,10,2) print (r[0])#Output:2print (r[3])#Output:8print (r[-1])#Output:8

### IndexError

Attempting to use an index that is too large will result in an IndexError.

r=range(2,10,2) print (r[4])#Output:IndexError: range object index out of range

### 3. Slicing:

Slicing is supported by the range object.

Refer to my story of Indexing and Slicing.

In slicing, we can specify a range of indexes.

s[i:j:k] — slice ofsfromitojwith stepk

Example: `s[1:3] `

— Returns element from the first index to the third index(excluded).

r=range(2,10,2) print (list(r[1:3]))#Output:[4, 6]

**4.len()**

Returns the number of elements in the range object.

**Example:**

r=range(2,10,2) print (len(r))#Output:4

**5.min()**

Returns the smallest element in the range object.

r=range(2,10,2) print (min(r))#Output:2r1=range(-10,-20,-2) print(min(r1))#Output:-18

**6.max()**

Returns the largest element in the range object.

r=range(2,10,2) print (max(r))#Output:8r1=range(-10,-20,-2) print(max(r1))#Output:-10

**7.index()**

Returns the index of the specified element in the range object. If the element is not in the range object means, it will raise a ValueError.

r=range(2,10,2) print (r.index(4))#Output:1print (r.index(10))#Output:ValueError: 10 is not in range

#### Concatenation and repetition operator:

The concatenation and repetition operator is not supported in the range object.

Range object only supports item sequences that follow specific patterns, and hence don’t support sequence **concatenation or repetition**.

**Concatenation**is not supported in range objects.

r1=range(5) r2=range(10) print (r1+r2)#Output:TypeError: unsupported operand type(s) for +: 'range' and 'range'

- The
**repetition**operator is not supported in the range object.

r1=range(5) print (r1*2)#Output:TypeError: unsupported operand type(s) for *: 'range' and 'int'

**Concatenation by using itertools.chain()**

Python doesn’t have a built-in function to concatenate two or more range objects. We can achieve this by using **itertools.chain().**

**chain():**Makes an iterator that returns an element from the first iterable until its exhausted, then proceeds to the next iterable. It will treat consecutive sequences as a single sequence.

`itertools.chain(*iterables)`

**Example:**

importitertools r=range(2,10,2) r1=range(-10,-20,-2) r2=itertools.chain(r,r1) print (list(r2))#Output:[2, 4, 6, 8, -10, -12, -14, -16, -18]

**Advantage of range function:**

The advantage of the

rangetype over a regularlistortupleis that a range object will always take the same (small) amount of memory, no matter the size of the range it represents (as it only stores the`,`

start`and`

stop`values).`

step

#### Conclusion:

- The
**range**function supports only**integers.**(either built-in`int`

or any object that implements the`__index__`

special method) - If the step is 0, it will raise
**ValueError.** - The
**range**function doesn’t support**concatenation**and**repetition**. - Python doesn’t have a built-in function to concatenate two or more range objects. We can achieve this by using
**itertools.chain().**

#### Resources(Python Documentation):

**Common Sequence Operations**

https://docs.python.org/3/library/stdtypes.html#sequence-types-list-tuple-range

**range**

https://docs.python.org/3/library/stdtypes.html#sequence-types-list-tuple-range

**range function**

https://docs.python.org/3/library/stdtypes.html#sequence-types-list-tuple-range

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