Fast Python loops
python.org
Fast Python loops
1–10 of 54 posts
Re: Fast Python loops
#2doesn't 'b' in array.array('b'... and 'B' denote unsigned and signed conversion, thus the 0-256 as desired? or am i missing something?
Re: Fast Python loops
#3Interesting read! I'm still missing what "B" in the Python code referring to as well.
Re: Fast Python loops
#4I wonder if bytearray([97,98,99]).decode('latin-1') is faster still.
Edit: Yup, it is. 3x faster. https://gist.github.com/anonymous/18e372e8d0173e77b5c405920d...
Re: Fast Python loops
#5[deleted]
Re: Fast Python loops
#6The author states:
"There's a general technique to avoid quadratic behavior in algorithms like this. I coded it as follows for strings of exactly 256 items:"
def f5(list):
string = ""
for i in range(0, 256, 16): # 0, 16, 32, 48, 64, ...
s = ""
for character in map(chr, list[i:i+16]):
s = s + character
string = string + s
return string
Re: Fast Python loops
#7According to archive.org this essay is from at most June 2006, which would put it at Python 2.4 or earlier. The specific performance characteristics of Python will have changed greatly in the intervening period.
Re: Fast Python loops
#8Interesting read! I'm still missing what "B" in the Python code referring to as well.
array.array isn't a normal python array. It's an optimized type/object where all the elements of the array are of the same type. The 'B' is a format string that indicates what type you want the elements to be. B == unsigned char
He's using it because it converts the int 65 to the string 'A', then toString() to join all the array elements together.
https://docs.python.org/2/library/array.html
See my other post though, it's not the fastest way to do this in python.
Re: Fast Python loops
#9No list comprehension?
I thought list comprehension were faster than loops?
Re: Fast Python loops
#10Interesting read! I'm still missing what "B" in the Python code referring to as well.
array.array isn't a normal python array. It's an optimized type/object where all the elements of the array are of the same type. The 'B' is a format string that indicates what type you want the elements to be. B == unsigned char He's using it because it converts the int 65 to the string 'A', then toString() to join all the array elements together. https://docs.python.org/2/library/array.html See my other post though,…
Great thanks! I have assume array.array is similar to 2-dimensional array.