About float/double type number in range.

[Peter J. Holzer]

On 2020-08-26 22:40:36 +1200, dn via Python-list wrote:
> On 26/08/2020 19:58, Joel Goldstick wrote:
> > On Wed, Aug 26, 2020 at 3:43 AM ADITYA <gautam.goari123 at gmail.com> wrote:
> > >     Dear Sir/Ma’am
> > > 
> > >     I am requesting you to satisfy me about float number in Range
> > >     function, because in the argument of range we can take integer
> > >     but not double or float whenever double as well as float are
> > >     integer in nature but when we use double/float in, it gives
> > >     error that- “'float' object cannot be interpreted as an
> > >     integer.” If we want to increment the number by half or
> > >     quarter what can I do.
> > > 
> > >     For ex- Range(1,3,0.5) I want it gives Output as [1 1.5 2 2.5 3)
> > > 
> > 
> > Take a look at this:
> > > > > l = [i/2 for i in range(2,7)]
> > > > > l
> > [1.0, 1.5, 2.0, 2.5, 3.0]
> 
> 
> This is a neat solution! To make it more user-friendly, the above needs to
> be wrapped in a convenience function that the user can call using arguments
> like "(1,3,0.5)" and not have to think about the 'multiplies' and 'divides'.
> 
[...]
> <<< Code NB Python v3.8 >>>
> def fp_range( start:float, stop:float, step:float=1.0 )->float:
>     """Generate a range of floating-point numbers."""
>     if stop <= start:
>         raise OverflowError( "RangeError: start must be less than stop" )
>     x = start
>     while x < stop:
>         yield x
>         x += step

This is almost the same solution as I came up with, but note that this
is not quote the same as what Joel proposed. Repeated addition is not
the same as multiplication with floating point numbers. 

A generator based on Joel's idea would look like this:

def fp_range(start, end, step):
    v = start
    n = int(math.ceil((end - start) / step))
    for i in range(n):
        yield start + i * step

(I omitted the OverflowError: range() doesn't raise one, either)

        hp

-- 
   _  | Peter J. Holzer    | Story must make more sense than reality.
|_|_) |                    |
| |   | hjp at hjp.at         |    -- Charles Stross, "Creative writing
__/   | http://www.hjp.at/ |       challenge!"
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