On May 6, 5:40 pm, Akshay Srinivasan <[email protected]>
wrote:
> Vinzent Steinberg wrote:
> > On May 4, 3:31 pm, Akshay Srinivasan <[email protected]>
> > wrote:
>
> >> Vinzent , I wanted to know how you planned to change the terms after
> >> they were returned by find. This isn't entirely obvious to me. Shouldn't
> >> the replacement part be inside find itself ?
>
> > This is a good question. :) Sympy expressions are immutable, so it's
> > necessary to rebuild the whole expression with the replacements
> > applied. I did not want to cope with this, so I just intended to write
> > a function that finds all occurrences of a certain pattern (for
> > example sin(x)/cos(x)) in an expression. Using this, I could just pass
> > over the job to subs. Of course this is quite inefficient, but it
> > should work. :)
>
> > Vinzent
>
> >>> expr=tan(x**2)+x**2
> >>> find(expr,a**2)
> [x**2,x**2]
>
> but,
> >>> expr=tan(x) + x
> >>> find(expr,a)
> [tan(x), x, x]
>
> This returns everything in the expression instead of giving [x,x] . I
> guess this has something to do with expr.match ?
If you used
>>> a = Wild('a')
this is the expected behavior, because Wild('a') matches anything.
Vinzent
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