Performance Issues please help

[Michael Spencer]

Michael Spencer wrote:
  > def search1(m):
>      box = {}
>      for r,row in enumerate(m):
>          for c,e in enumerate(row):
>              try:
>                  minc, minr, maxc, maxr = box[e]
>                  box[e] = ( c < minc and c or minc,
>                             r < minr and r or minr,
>                             c > maxc and c or maxc,
>                             r > maxr and r or maxr)
>              except KeyError:
>                  box[e] = (c, r, c, r)
>      return box
> 
> Michael
> 

Sorry, my earlier solution was incorrect since:
     c < minc and c or minc # evaluates to minc if c == 0
Two of the tests are unnecessary, as pointed out by Peter
The remaining test:
     c > maxc and c or maxc
does not suffer from the same problem, since c cannot both be 0 and greater than 
maxc

The following version, still untested ;-) has the correction:

def search2(m):
     box = {}
     for r,row in enumerate(m):
         for c,e in enumerate(row):
             try: # use this form if e will be found 90%+ of the time
		 # otherwise, use: if e in box:
                 minc, minr, maxc, maxr = box[e]
                 # note correction for c == 0
                 # also Peter's simplification
                 box[e] = ( c and (c < minc and c or minc),
                            minr,
                            c > maxc and c or maxc,
                            r)

             except KeyError:
                 box[e] = (c, r, c, r)
     return box

Michael