Re: faster "stringification"
On Sunday, 11 December 2016 at 10:01:21 UTC, Orut wrote: On Sunday, 11 December 2016 at 02:46:58 UTC, Nicholas Wilson wrote: 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. Thanks, Stefan and Nicholas. I think joiner did the trick (for 50M iterations, ~2s for D, ~17s for Python). Excellent. that seem more like the numbers i would expect.
Re: faster "stringification"
On Sunday, 11 December 2016 at 02:46:58 UTC, Nicholas Wilson wrote: 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. Thanks, Stefan and Nicholas. I think joiner did the trick (for 50M iterations, ~2s for D, ~17s for Python).
Re: faster "stringification"
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(1000): # 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.
Re: faster "stringification"
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(1000): # 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?
Preallocate a static array for your result.
