Re: [gentoo-user] Re: Python precision

[Helmut Jarausch]

On 09/21/2012 08:31:45 AM, Philip Webb wrote:
> 120920 Willie WY Wong wrote:
> > Unless you want to load the math module every time you start Python,
> > it is perhaps better to create an alias in Bash
> > using the `-i' option of Python:
> >   alias python-calc='python -i loadmath.py'
> > or if you only need one single command
> >   alias python-calc='python -i -c "from math import *"'
> > which will give you an interactive session with math functions
> preloaded.
>
> Yes thanks: the 2nd is the simplest way to do what I want.
>
> > 120919 Marc Joliet described how to set a level of precision:
>
> Thanks too, but that's not what I wanted: it's not for printing,
> but simply to limit the display to eg  4  decimal places, not  16 ;
> the calculations still wb as accurate, but the output easier to read.
> Is that possible with Python ? -- ie a setting in  ascript.py
> to tell Python to display only the 1st  4  places in all output
> without any further input from the user when doing the calculations;
> presumably it wb a command s/he could enter when in interactive mode
> too.
>

You could subclass the builtin float class like

#!/usr/bin/python3
class myfloat(float) :
   def __init__(self,value):
     super().__init__(self,value)
   def __str__(self):
     S= super().__str__()
     return S[:5]

X=3.1415926
print(myfloat(X))


Helmut.