Jython decimal places for floats only when needed

Question

I am searching for the functionality in Jython, that the ouput of a float only has decimal points when it isn't an integer.

I've found:

>>> x = 23.457413902458498
>>> s = format(x, '.5f')
>>> s
'23.45741'

But

>>> y=10
>>> format(y, '.2f')
'10.00'

In this case I would like to have only

'10'

Can you help me?!

Thank you for your help!!!

Answer 1

Try the 'g' (for "general") format specification for floats (docs):

>>> format(23.4574, '.4g')
'23.46'
>>> format(10, '.4g')
'10'

Notice that the number given isn't digits after the decimal point, it's precision (number of significant digits), which is why the first example keeps 4 digits from the input.

If you want to specify digits after the decimal point but remove trailing zeros, implement this directly:

def format_stripping_zeros(num, precision):
  format_string = '.%df' % precision
  # Strip trailing zeros and then trailing decimal points.
  # Can't strip them at the same time otherwise formatting 10 will return '1'
  return format(num, format_string).rstrip('0').rstrip('.')

>>> format_stripping_zeros(10, precision=2)
'10'
>>> import math
>>> format_stripping_zeros(math.pi, precision=5)
'3.14159'

Answer 2

This will work in Jython 2.7 where x is your float to be formatted and the value after the else will set your number of decimal places:

"{0:.{1}f}".format(x, 0 if x.is_integer() else 2)