[Tutor] mapping/filtering a sequence

[Martin A. Brown]

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 : I am doing some data massage, minor mapping and filtering really 
 : and i find that i have a lot of this kind of kludgy code:
 : 
 : # -- -------------------------
 : def filt_seq(inseq):
 : 	out_list = []
 : 	for item in inseq:
 : 		# 38 needs to be mapped on to 34 as we don't have a 38 in our
 : 		grid
 : 		if item == 38:
 : 			item = item - 4
 : 			out_list.append(item)
 : 		# We also don't have a 40, but we do have a 39. Map that
 : 		sucka
 : 		elif item == 40:
 : 			item = item - 1
 : 			out_list.append(item)
 : 		# if we get values that fall in good places, just pass them
 : 		on to the out seq
 : 		else:
 : 			out_list.append(item)
 : 	return out_list
 : 
 : # -- -------------------------
 : 
 : To do some basic jiggering of some out of range off grid data.
 : 
 : There has to be a better, more elegant, more flexible less brute 
 : force more pythonic way to do this kind of mapping no?

Have you discovered the map() builtin yet?

I would imagine that others on this list will have some even more 
elegant and efficient solutions for you, but here's a possibility:

  def filt_seq( thing ):
    if thing == 38:
      thing = thing - 4
    elif thing == 40:
      thing = thing - 1
    return thing
  
  l = [ 1, 17, 12, 38, 4, 40, 17, 19 ]
  l = map( filt_seq, l )

Good luck,

- -Martin

- -- 
Martin A. Brown
http://linux-ip.net/
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