Find Semantically Correct Word Splits in UTF-8 Strings
I'm looking for a way to make my algorithm
S[] findWordSplit(S)(S word,
HLang[] langs = [])
{
for (size_t i = 1; i + 1 < word.length; i++)
{
const first = word[0..i];
const second = word[i..$];
if (this.canMeanSomething(first, langs) &&
this.canMeanSomething(second, langs))
{
return [first,
second];
}
}
return typeof(return).init;
}
correctly work if S is a (UTF-8) string without first, in lazy
manner, encode word to a dstring.
Currently this algorithm works as
"carwash" => ["car", "wash"]
and I would like it to work correctly and efficient in my native
language aswell as
"biltvätt" => ["bil", "tvätt"]
:)
Re: Find Semantically Correct Word Splits in UTF-8 Strings
On Wednesday, 1 October 2014 at 11:06:24 UTC, Nordlöw wrote:
I'm looking for a way to make my algorithm
Update:
S[] findMeaningfulWordSplit(S)(S word,
HLang[] langs = []) if
(isSomeString!S)
{
for (size_t i = 1; i + 1 < word.length; i++)
{
const first = word.takeExactly(i).to!string;
const second = word.dropExactly(i).to!string;
if (this.canMeanSomething(first, langs) &&
this.canMeanSomething(second, langs))
{
return [first,
second];
}
}
return typeof(return).init;
}
works but has unfortunately O(word.length^^2) time-complexity.
Do we need a new InputRange algorithm for this?
Re: Find Semantically Correct Word Splits in UTF-8 Strings
On Wednesday, 1 October 2014 at 11:47:41 UTC, Nordlöw wrote: Do we need a new InputRange algorithm for this? If so, how about naming it SlidingSplitter or perhaps SlidingHalver in the binary case? I haven't thought about making this variadic on the number of splits (>= 1) but that could be useful in my application aswell.
Re: Find Semantically Correct Word Splits in UTF-8 Strings
S[] findMeaningfulWordSplit(S)(S word,
HLang[] langs = []) if
(isSomeString!S)
{
S second = word;
for (size_t i = 1; i + 1 < word.length; i++)
{
second = second.dropExactly(i).to!string;
const first = word[0..$-second.length];
if (this.canMeanSomething(first, langs) &&
this.canMeanSomething(second, langs))
{
return [first,
second];
}
}
return typeof(return).init;
}
Re: Find Semantically Correct Word Splits in UTF-8 Strings
On Wednesday, 1 October 2014 at 11:47:41 UTC, Nordlöw wrote:
On Wednesday, 1 October 2014 at 11:06:24 UTC, Nordlöw wrote:
I'm looking for a way to make my algorithm
Update:
S[] findMeaningfulWordSplit(S)(S word,
HLang[] langs = []) if
(isSomeString!S)
{
for (size_t i = 1; i + 1 < word.length; i++)
{
const first = word.takeExactly(i).to!string;
const second = word.dropExactly(i).to!string;
if (this.canMeanSomething(first, langs) &&
this.canMeanSomething(second, langs))
{
return [first,
second];
}
}
return typeof(return).init;
}
works but has unfortunately O(word.length^^2) time-complexity.
Do we need a new InputRange algorithm for this?
This seems like a text-book case for a trie algorithm:
http://en.wikipedia.org/wiki/Trie
Once your "dictionary" is built, it can find *all* the splits in
O(word.length).
...but I don't know how well it adapts to the range interface.
Should still work though.
Also, Aho–Corasick might be relevant depending on what you want
to do, for example, find all substrings that happen to be a word,
regardless of what comes before or after:
http://en.wikipedia.org/wiki/Aho%E2%80%93Corasick_string_matching_algorithm
Re: Find Semantically Correct Word Splits in UTF-8 Strings
On Wednesday, 1 October 2014 at 11:06:24 UTC, Nordlöw wrote:
I'm looking for a way to make my algorithm
S[] findWordSplit(S)(S word,
HLang[] langs = [])
{
for (size_t i = 1; i + 1 < word.length; i++)
{
const first = word[0..i];
const second = word[i..$];
if (this.canMeanSomething(first, langs) &&
this.canMeanSomething(second, langs))
{
return [first,
second];
}
}
return typeof(return).init;
}
correctly work if S is a (UTF-8) string without first, in lazy
manner, encode word to a dstring.
Currently this algorithm works as
"carwash" => ["car", "wash"]
and I would like it to work correctly and efficient in my
native language aswell as
"biltvätt" => ["bil", "tvätt"]
:)
Out of curiosity, why exactly isn't it working in your "native
language"? If you avoid decoding in your "canMeanSomething", you
should encounter no problems.
Re: Find Semantically Correct Word Splits in UTF-8 Strings
On Wednesday, 1 October 2014 at 16:44:24 UTC, monarch_dodra wrote: language"? If you avoid decoding in your "canMeanSomething", you should encounter no problems. You're right. I'll try that.
Re: Find Semantically Correct Word Splits in UTF-8 Strings
On Wednesday, 1 October 2014 at 11:47:41 UTC, Nordlöw wrote:
On Wednesday, 1 October 2014 at 11:06:24 UTC, Nordlöw wrote:
I'm looking for a way to make my algorithm
Update:
S[] findMeaningfulWordSplit(S)(S word,
HLang[] langs = []) if
(isSomeString!S)
{
for (size_t i = 1; i + 1 < word.length; i++)
{
const first = word.takeExactly(i).to!string;
Does that even work? takeExactly would pop up to N *codepoints*,
whereas your string only has N *codeunits*.
Something like:
for (auto second = str ; !second.empty ; second.popFront() )
{
auto first = str[0 .. $ - second.length];
...
}
//special case str + str[$ .. $] here. (or adapt your loop)
Would also be unicode correct, without increasing the original
complexity.
Re: Find Semantically Correct Word Splits in UTF-8 Strings
On Wednesday, 1 October 2014 at 17:09:57 UTC, monarch_dodra wrote: Does that even work? takeExactly would pop up to N *codepoints*, whereas your string only has N *codeunits*. Your're right again :) If forgot that takeExactly auto-decodes.
Re: Find Semantically Correct Word Splits in UTF-8 Strings
On Wednesday, 1 October 2014 at 21:34:40 UTC, Nordlöw wrote: On Wednesday, 1 October 2014 at 17:09:57 UTC, monarch_dodra wrote: Does that even work? takeExactly would pop up to N *codepoints*, whereas your string only has N *codeunits*. Your're right again :) If forgot that takeExactly auto-decodes. Technically, it only pops. It's front/popFront that auto-decode.
Re: Find Semantically Correct Word Splits in UTF-8 Strings
On Thursday, 2 October 2014 at 13:21:24 UTC, monarch_dodra wrote: Technically, it only pops. It's front/popFront that auto-decode. Thanks again. I decided to try to expand D-universe by expressing this through a new range. For details see: http://forum.dlang.org/thread/uzrbmjonrkixojzfl...@forum.dlang.org#post-uzrbmjonrkixojzflbig:40forum.dlang.org
