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Add similarity comparison to String

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Uses the Sorensen-Dice coefficient to calculate similarity. This also adds
String.bigrams() as a convenience function needed by the comparison.
This commit is contained in:
George Marques 2016-06-13 14:06:03 -03:00
parent f47d7b27cb
commit 1b8d0a16b7
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GPG key ID: 046BD46A3201E43D
3 changed files with 50 additions and 0 deletions
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44
core/ustring.cpp
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@ -2810,6 +2810,50 @@ bool String::_base_is_subsequence_of(const String& p_string, bool case_insensiti
return false;
}
Vector<String> String::bigrams() const {
int n_pairs = length() - 1;
Vector<String> b;
if(n_pairs <= 0) {
return b;
}
b.resize(n_pairs);
for(int i = 0; i < n_pairs; i++) {
b[i] = substr(i,2);
}
return b;
}
// Similarity according to Sorensen-Dice coefficient
float String::similarity(const String& p_string) const {
if(operator==(p_string)) {
// Equal strings are totally similar
return 1.0f;
}
if (length() < 2 || p_string.length() < 2) {
// No way to calculate similarity without a single bigram
return 0.0f;
}
Vector<String> src_bigrams = bigrams();
Vector<String> tgt_bigrams = p_string.bigrams();
int src_size = src_bigrams.size();
int tgt_size = tgt_bigrams.size();
float sum = src_size + tgt_size;
float inter = 0;
for (int i = 0; i < src_size; i++) {
for (int j = 0; j < tgt_size; j++) {
if (src_bigrams[i] == tgt_bigrams[j]) {
inter++;
break;
}
}
}
return (2.0f * inter)/sum;
}
static bool _wildcard_match(const CharType* p_pattern, const CharType* p_string,bool p_case_sensitive) {
switch (*p_pattern) {
case '\0':

2
core/ustring.h
View file

@ -123,6 +123,8 @@ public:
bool ends_with(const String& p_string) const;
bool is_subsequence_of(const String& p_string) const;
bool is_subsequence_ofi(const String& p_string) const;
Vector<String> bigrams() const;
float similarity(const String& p_string) const;
String replace_first(String p_key,String p_with) const;
String replace(String p_key,String p_with) const;
String replacen(String p_key,String p_with) const;

4
core/variant_call.cpp
View file

@ -249,6 +249,8 @@ static void _call_##m_type##_##m_method(Variant& r_ret,Variant& p_self,const Var
VCALL_LOCALMEM1R(String,ends_with);
VCALL_LOCALMEM1R(String,is_subsequence_of);
VCALL_LOCALMEM1R(String,is_subsequence_ofi);
VCALL_LOCALMEM0R(String,bigrams);
VCALL_LOCALMEM1R(String,similarity);
VCALL_LOCALMEM2R(String,replace);
VCALL_LOCALMEM2R(String,replacen);
VCALL_LOCALMEM2R(String,insert);
@ -1274,6 +1276,8 @@ _VariantCall::addfunc(Variant::m_vtype,Variant::m_ret,_SCS(#m_method),VCALL(m_cl
ADDFUNC1(STRING,BOOL,String,ends_with,STRING,"text",varray());
ADDFUNC1(STRING,BOOL,String,is_subsequence_of,STRING,"text",varray());
ADDFUNC1(STRING,BOOL,String,is_subsequence_ofi,STRING,"text",varray());
ADDFUNC0(STRING,STRING_ARRAY,String,bigrams,varray());
ADDFUNC1(STRING,REAL,String,similarity,STRING,"text",varray());
ADDFUNC2(STRING,STRING,String,replace,STRING,"what",STRING,"forwhat",varray());
ADDFUNC2(STRING,STRING,String,replacen,STRING,"what",STRING,"forwhat",varray());