How to format a float with a maximum number of decimal places and without extra zero padding?

Question

I need to do some decimal place formatting in python. Preferably, the floating point value should always show at least a starting 0 and one decimal place. Example:

Input: 0 Output: 0.0 

Values with more decimal places should continue to show them, until it gets 4 out. So:

Input: 65.53 Output: 65.53  Input: 40.355435 Output: 40.3554 

I know that I can use {0.4f} to get it to print out to four decimal places, but it will pad with unwanted 0s. Is there a formatting code to tell it to print out up to a certain number of decimals, but to leave them blank if there is no data? I believe C# accomplishes this with something like:

floatValue.ToString("0.0###") 

Where the # symbols represent a place that can be left blank.

Answer 1

What you're asking for should be addressed by rounding methods like the built-in round function. Then let the float number be naturally displayed with its string representation.

>>> round(65.53, 4)  # num decimal <= precision, do nothing '65.53' >>> round(40.355435, 4)  # num decimal > precision, round '40.3554' >>> round(0, 4)  # note: converts int to float '0.0' 

Answer 2

Sorry, the best I can do:

' {:0.4f}'.format(1./2.).rstrip('0') 

Corrected:

ff=1./2. ' {:0.4f}'.format(ff).rstrip('0')+'0'[0:(ff%1==0)]