CODEWITHSUNDEEP
python
skytt4
skytt4

Reputation: 65

How to print a float variable using the % formatting?

I'm using Python 3.7.1 on Windows. When I print a float variable using the % formatting. only the natural part is printed. Here is an example:

result_2 = 4.523529411764706
statement_2a = "Your text contains an average length of %d letter(s) per words." % result_2

print(result_2)
print(statement_2a)

This gives the following result:

4.523529411764706
Your text contains an average length of 4 letter(s) per words.

But what I actually want is:

Your text contains an average length of 4.5235 letter(s) per words.
  1. How do I prevent the print() function from practically deleting the decimal numbers?
  2. How to round the number to four decimal digits

Thanks in advance!

Upvotes: 3

Views: 40090

Answers (4)

FChm
FChm

Reputation: 2580

There are several options to evaluate expressions and print them as a string in python.

There are already some good answers, but here are some explicit examples and links to the documentation.

Formatted string literals (f-strings)

f-strings allow you to input expressions which are evaluated at run-time. In the f strings expressions are encased by curly brackets.

As an example:

x = 42.222222222

print(f'My value is: {x}')

prints My value is: 42.222222222.

and with specifying the format:

x = 42.222222222

print(f'My value is: {x:.2f}')

prints My value is: 42.22.

Str formatting method

Strings have a built-in .format() method where you can specify replacement fields with curly brackets.

As an example:

x = 42.222222222

print('My value is: {}'.format(x))

prints My value is: 42.222222222.

and with string formatting:

x = 42.222222222

print('My value is: {:.2f}'.format(x))

prints My value is: 42.22.

String formatting operator

String formatting operator

As an example:

x = 42.222222222

print('My value is: %' % x)

prints My value is: 42.222222222.

and with string formatting:

x = 42.222222222

print('My value is: %.2f' % x)

prints My value is: 42.22.

See @Felk answer for some more qualitive descriptions of the different methods.

Upvotes: 10

Felk
Felk

Reputation: 8224

You are using "old-style" formatting and used %d as the placeholder. This will represent your number as a decimal number without any fractions. If you want to display floating point numbers, the placeholder is simply %f.

If you want to use the variable's string representation, you can also always just use %s. But since you are on python 3.7, there are some more modern approaches as well.

  • "old-style" formatting: "%s" % var
  • "new-style" formatting using format(): "{}".format(var) (Read up on python formatters for details)
  • f-strings, which are basically syntactic sugar for format()-based string interpolation. You prefix with f and put the variables in the string literal itself: f"{var}"

Upvotes: 1

skaul05
skaul05

Reputation: 2334

A better alternative than % formatting would be to use .format.

result_2 = 4.523529411764706
print(result_2)
print("Your text contains an average length of {} letter(s) per words.".format(result_2))

For rounding use round

result_2 = 4.523529411764706
print(result_2)
print("Your text contains an average length of {} letter(s) per words.".format(round(result_2,4)))

But if you feel comfortable with % formatting then to print whole number use %s

result_2 = 4.523529411764706
statement_2a = "Your text contains an average length of %s letter(s) per words." % result_2
print(result_2)
print(statement_2a)

For rounding to 4 digits use %1.4f

result_2 = 4.523529411764706
statement_2a = "Your text contains an average length of %1.4f letter(s) per words." % result_2
print(result_2)
print(statement_2a)

Upvotes: 1

Hiadore
Hiadore

Reputation: 714

As you try print float number, use %f instead of %d. This code will print the number to 4 decimal places:

result_2 = 4.523529411764706
statement_2a = "Your text contains an average length of %.4f letter(s) per words." % result_2

print(result_2)
print(statement_2a)

Upvotes: 3

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