The Interpolation Operator - Python

When we wish to specify what happens to a value when we insert it into a string, we can do so using the interpolation operator(%). We can use this to insert data inside of a string, determine how many digits are displayed next to a decimal, determine how much space to allow for the data (known as the minimum field width), and more.

Here is a list of possible formatting code you can insert after the interpolation operator(%):

• %c - used for a single character

• %d and %i - used for signed integer decimals

• %f and %F - used for floating point decimals

• %r - represents the data

• %% - used as an escape character for the percentage symbol

To insert a single character into a string, we can do so, as described above, using %c. Here it is in code:

missing='F'

print 'Which character is missing from the following sequence?'

print 'A B C D E %c G H I J K L M N O P Q R S T U V W X Y Z' %missing

When the code prints, it replaces the code %c with the value in our variable, missing, which in this instance is 'F'. Here is the result:

  Which character is missing from the following sequence?

  A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

If we wanted to insert an entire word or sentence, or string, we could do that as well by using %s:

hawtness='James Payne'

print "And the winner of this years Uber Hawtness award goes to....*drumroll*"

print "The magnanimous, heroic, super-strong, giant-brained, whicka whicka %s ! Whoeee!" %hawtness

In this code, the program sees the %s and replaces it with the value stored in the variable hawtness. The result is:

  And the winner of this years Uber Hawtness award goes to....*drumroll*

  The magnanimous, heroic, super-strong, giant-brained, whicka whicka James   Payne ! Whoeee!

We can, of course, also insert multiple words into our string, using the following method:

hawtness='James Payne'

gf='Angelina Jolie'

name='Jamesalina'

print 'Here comes the hot new hollywood couple now.'

print '%s in an Armani suit, looking dashing and %s in a birthday suit as %s demands it!' % (hawtness, gf, hawtness)

print 'As a couple we dub thee...%s' %name

This displays:

  Here comes the hot new hollywood couple now.

  James Payne in an Armani suit, looking dashing and Angelina Jolie in a birthday suit as James Payne demands it!

  As a couple we dub thee...Jamesalina

The technique works for characters as well:

first='a'

second='b'

third='c'

fourth='d'

fifth='e'

sixth='f'

seventh='g'

eighth='h'

print 'Here are the first eight letters of the alphabet...'

print '%c %c %c %c %c %c %c %c' % (first, second, third, fourth, fifth, sixth, seventh, eighth)

And the result:

  Here are the first eight letters of the alphabet...

  a b c d e f g h