String Slicing in python

String Slicing Python 

Slicing refers to extracting some words from a string. As in many other languages there are many different concepts for extracting a letters or words from a string ,in python we are having the concept of slicing. We can also the same things using looping, we will learn about it in our next tutorials.

Indexing in Strings

Before starting slicing, we need to understand the indexing in python. We have the concept of positive indexing  and  negative indexing. 

Positive indexing starts from 0 to (length of string).It goes from forward to backward.

Negative indexing starts from -1 to -(length of string + 1).

It is illustrated in below example

Below are some examples of how to use string slicing to extract characters from string.

Accessing the characters in a string using positive index

eg.

string="We are studying string slicing"
s=string[0] # A single character will be printed present at index 0
w=string[4] # A single character will be printed present at index 4
q=string[6]# A space is being stored in q as space is stored at index 6
print(s)
print(q) # A single space will be printedprint(w)

Output:

W

r

Accessing the characters in a string using negative index

eg.

string="We are studying string slicing"
s=string[-1] # Last character from the string will be printed
w=string[-5] #  -5 index is equivalent to 25
t=string[25] 
print(s)
print(w)
print(t)

Output:

g

i

i

Slicing

We can extract the range of characters from string by providing indices in square brackets as [x:y:z]

where,

x= Starting Index (from where you want to extract)

y= Ending  Index(upto where you want to extract)

z= Jump(Number of characters you want to jump)

Note: Always keep one thing in mind that characters are printed from index x to y-1 

We will understand the following with the help of examples:

eg.

string="We do great things here"
s=string[0:5]

w=string[-4:-1] 

t=string[6:-5]
print(s)
print(w)
print(t)

Output:

We do

her

great things

eg.

string="We do great things here"
s=string[0:5:2]

t=string[6:-5:3]
print(s)
print(t)

Output:

W o

gatn

Here we are seeing that string skips number of positions that is given in z position i.e 

s will print characters at 0,2 and 4 index

t will print characters at  6,9,12 and 15 index

Slicing without some parameters

eg.

string="We do great things here"
s=string[0::2]

m=string[::]

p=string[1:]

q=string[:7]

t=string[:-5:3]

print(s)
print(m)
print(p)
print(q)
print(t)

Output:

W ogettig ee

We do great things here

e do great things here

We do g

Wdgatn

Here we see that string slicing also work when no arguments are given.It automatically takes whole string if no arguments are given.