On 10/04/2014 10:36 AM, Shiva wrote:
What I don't understand is:
for w in eachword:
textstorage[w]=textstorage.get(w, 0) + 1
How does textstorage.get(w,0)+1 give the count of the word??
Very long-winded explanation: (But to shorten it a bit, I'm going to use ts in place of
textstorage. Also lhs = left-hand-side and rhs = right-hand-side.)
What we're trying to do here is to update the word count. We could
(erroneously) write it as:
ts[w] = ts[w] + 1
If w already exists in the ts dictionary, this works fine. But if it does not it will abort
with a KeyError when it comes to the ts[w] on the rhs of the assignment.
The get() method is an alternate way of accessing the value of a key in a dictionary, but with a
default value given as well. Now let's break down the statement
ts[w] = ts.get(w, 0) + 1
Case 1: w already exists in the ts dictionary:
ts.get(w, 0) gets the value of ts[w] (the current word count), adds 1, which is then used to
update the word-count value of ts[w] (on the lhs of the assignment).
case2: w does not exist in the ts dictionary:
ts.get(w, 0) gives the default value of 0, and 1 is added to that. ts[w] on the lhs of the
assignment does not exist, so a new entry is created in the ts dictionary with the given w as
the key, and the value is initialized with the 1 from the get()+1.
Make sense?
-=- Larry -=-
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