Help with dictionary, please

[Frank Niessink]

rbl at hal.cwru.edu wrote:
> 	if prev1 != '' and prev2 != '':
> 	 	   key = (prev2,prev1)
> 	           dict[key] = dict[key] + 1
>    and got this error:
> 	  File "Metro:Python 1.5.1:learn2.py", line 34
>           dict[key] = dict[key] + 1
>                          ^
> 	SyntaxError: invalid token

You need to initialize the value at dict[key], it is not automatically
set to 0 or something like that. For example:

	if dict.has_key(key):
		dict[key] = dict[key] + 1
	else:
		dict[key] = 1

However, you should've got a KeyError, I don't understand why you're
getting the SyntaxError...  

HTH, Frank

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