CODEWITHSUNDEEP
python
Joyal Mathew
Joyal Mathew

Reputation: 624

Assign known values instead of calculating them?

If I am creating a program that does some complex calculations on a data set and I already know what some of the values should be, should I still calculate them? For example if I know that 0 or 1 would always be themselves should I just check if the value is 0 or 1 or actually do the calculations?

Edit:

I don't have code because I was asking as a concept. I was creating a program to return the base 10 log of each number in a data set and I was wondering if it would be more efficient to return values I already knew like 0 for 1, "undefined" for 0, and the number of zeros for numbers divisible by 10. I wasn't sure if it was more efficient and if it would be efficient on a larger scale.

Upvotes: 0

Views: 53

Answers (1)

John La Rooy
John La Rooy

Reputation: 304147

Let's try this simple example

$ python3 -m timeit -s "from math import log; mylog=lambda x: log(x)" "mylog(1)"
10000000 loops, best of 3: 0.152 usec per loop
$ python3 -m timeit -s "from math import log; mylog=lambda x: 0.0 if x==1 else log(x)" "mylog(1)"
10000000 loops, best of 3: 0.0976 usec per loop

So there is some speedup, however. All the non special cases run slower

$ python3 -m timeit -s "from math import log; mylog=lambda x: log(x)" "mylog(2)"
10000000 loops, best of 3: 0.164 usec per loop
$ python3 -m timeit -s "from math import log; mylog=lambda x: 0.0 if x==1 else log(x)" "mylog(2)"
1000000 loops, best of 3: 0.176 usec per loop

And in this case, it's better just to leave the wrapper function out altogether

$ python3 -m timeit -s "from math import log" "log(2)"
10000000 loops, best of 3: 0.0804 usec per loop

Upvotes: 1

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