[Tutor] Bigrams and nested dictionaries

[Kent Johnson]

Michael Broe wrote:

> dict = {}

dict is the name of the builtin dictionary class, so you shouldn't use 
it as the name of your dict - you shadow the built-in name. file is also 
a built-in name.
> 
> L = file[0]
> for R in file[1:]:	# move right edge of window across the file
> 	if not L in dict:
> 		dict[L] = {}
> 		
> 	if not R in dict[L]:
> 		dict[L][R] = 1
> 	else:
> 		dict[L][R] += 1

I might write it this way:
   dictL = dict.setdefault(L, {})
   dictL[R] = dictL.setdefault(R, 0) + 1
though I'm not sure which way will be faster.

Kent