Python speed-up

Guyon Morée gumuz at NO_looze_SPAM.net
Wed Sep 22 16:06:04 CEST 2004


Hi all,

I am working on a Huffman encoding exercise, but it is kinda slow. This is
not a big problem, I do this to educate myself :)

So I started profiling the code and the slowdown was actually taking place
at places where I didn't expect it.

after I have created a lookup-table-dictionary with encodings like
{'d':'0110', 'e':'01' etc} to encode the original text like this:

for c in original_text:
    encoded_text += table[c]

I can appreciate the length of the text is big, but this isn't a problem at
character frequency counting for eaxample. Why is this slow?


the second place the slowdown occurs is when I ty to chop the encoded string
of 0's and 1's in pieces of eigth like this:

chr_list = [] # resulting list
while 1:
    chr_list.append(encoded_text[:8]) # take 8 bits from string and put them
in the list
    encoded_text = encoded_text[8:] # truncate the string
    if len(encoded_text) < 8: # end of string reached
        chr_list.append(encoded_text)
        break


I hope someone can tell me why these are slow.


regards,

Guyon





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