On Sunday, 11 December 2016 at 02:09:41 UTC, Orut wrote:
D nub here. I have a Python script that I'd like to implement in D. For certain parts, the D equivalent was slower than Python's. For example,

Python code:

#dummy code
s = ["abc", "fjkd", "L", "qwa", "r", "uw", "tiro", "bc", "sg", "k", "jds", "yd"];

for i in range(10000000): # a lot of array to string conversions '-'.join(s) # not assigning this to a variable to simplify comparison

D code:

import std.stdio;
import std.array;

void main(string[] args){
string[] s = ["abc", "fjkd", "L", "qwa", "r", "uw", "tiro", "bc", "sg", "k", "jds", "yd"]; for(int i; i<10_000_000; i++) s.join("-"); //see Python comments


Python was 2x faster.

How should I implement this in D?

join performs allocations which is probably the reason for its slowness. There is joiner (in std.algorithm.iterations) that lazily performs the join, (though in the case of this "benchmark" will be cheating because you don't do anything with the result, print it to get a more fair comparison) avoiding allocation.

see also appender (in std.array) for fast concatenation.

Reply via email to