* Created by Pat Schloss on 12/16/08.
* Copyright 2008 Patrick D. Schloss. All rights reserved.
*
+ * This class is a child class of the Database class, which stores the template sequences as a kmer table and provides
+ * a method of searching the kmer table for the sequence with the most kmers in common with a query sequence.
+ * kmerLocations is the primary storage variable that is a two-dimensional vector where each row represents the
+ * different number of kmers and each column contains the index to sequences that use that kmer.
+ *
+ * Construction of an object of this type will first look for an appropriately named database file and if it is found
+ * then will read in the database file (readKmerDB), otherwise it will generate one and store the data in memory
+ * (generateKmerDB)
+ *
+ * The search method used here is roughly the same as that used in the SimRank program that is found at the
+ * greengenes website. The default kmer size is 7. The speed complexity is between O(L) and O(LN). When I use 7mers
+ * on average a kmer is found in ~100 other sequences with a database of ~5000 sequences. If this is the case then the
+ * time would be on the order of O(0.1LN) -> fast.
+ *
+
*/
using namespace std;
string kmerDBName = fastaFileName.substr(0,fastaFileName.find_last_of(".")+1) + char('0'+ kmerSize) + "mer";
ifstream kmerFileTest(kmerDBName.c_str());
- int power4s[9] = { 1, 4, 16, 64, 256, 1024, 4096, 16384, 65536 };
+ int power4s[14] = { 1, 4, 16, 64, 256, 1024, 4096, 16384, 65536, 262144, 1048576, 4194304, 16777216, 67108864 };
maxKmer = power4s[kmerSize];
kmerLocations.resize(maxKmer+1);
- if(!kmerFileTest){
+ if(!kmerFileTest){ // if we can open the kmer db file, then read it in...
cout << "Generating the " << kmerDBName << " database...\t"; cout.flush();
generateKmerDB(kmerDBName);
}
- else{
+ else{ // ...otherwise generate it.
cout << "Reading in the " << kmerDBName << " database...\t"; cout.flush();
readKmerDB(kmerDBName, kmerFileTest);
}
/**************************************************************************************************/
Sequence* KmerDB::findClosestSequence(Sequence* candidateSeq){
+
+ vector<int> matches(numSeqs, 0); // a record of the sequences with shared kmers
+ vector<int> timesKmerFound(kmerLocations.size()+1, 0); // a record of the kmers that we have already found
- vector<int> matches(numSeqs, 0);
- vector<int> timesKmerFound(kmerLocations.size()+1, 0);
-
- int maxMatches = 0;
+ searchScore = 0;
int maxSequence = 0;
- string query = candidateSeq->getUnaligned();
-
- int numKmers = query.length() - kmerSize + 1;
+ string query = candidateSeq->getUnaligned(); // we want to search using an unaligned dna sequence
+
+ int numKmers = query.length() - kmerSize + 1;
Kmer kmer(kmerSize);
for(int i=0;i<numKmers;i++){
-
- int kmerNumber = kmer.getKmerNumber(query, i);
-
- if(timesKmerFound[kmerNumber] == 0){
- for(int j=0;j<kmerLocations[kmerNumber].size();j++){
- matches[kmerLocations[kmerNumber][j]]++;
+ int kmerNumber = kmer.getKmerNumber(query, i); // go through the query sequence and get a kmer number
+ if(timesKmerFound[kmerNumber] == 0){ // if we haven't seen it before...
+ for(int j=0;j<kmerLocations[kmerNumber].size();j++){//increase the count for each sequence that also has
+ matches[kmerLocations[kmerNumber][j]]++; // that kmer
}
}
- timesKmerFound[kmerNumber] = 1;
-
+ timesKmerFound[kmerNumber] = 1; // ok, we've seen the kmer now
}
- for(int i=0;i<numSeqs;i++){
- if(matches[i] > maxMatches){
- maxMatches = matches[i];
+
+ for(int i=0;i<numSeqs;i++){ // find the db sequence that shares the most kmers with
+ if(matches[i] > searchScore){ // the query sequence
+ searchScore = matches[i];
maxSequence = i;
}
}
- return templateSequences[maxSequence];
-
+ searchScore = 100 * searchScore / (float)numKmers;
+ return templateSequences[maxSequence]; // return the Sequence object corresponding to the db
+ // sequence with the most shared kmers.
}
/**************************************************************************************************/
void KmerDB::generateKmerDB(string kmerDBName){
-
Kmer kmer(kmerSize);
- for(int i=0;i<numSeqs;i++){
+ for(int i=0;i<numSeqs;i++){ // for all of the template sequences...
- string seq = templateSequences[i]->getUnaligned();
+ string seq = templateSequences[i]->getUnaligned(); // ...take the unaligned sequence...
int numKmers = seq.length() - kmerSize + 1;
- for(int j=0;j<numKmers;j++){
+ vector<int> seenBefore(maxKmer+1,0);
+ for(int j=0;j<numKmers;j++){ // ...step though the sequence and get each kmer...
int kmerNumber = kmer.getKmerNumber(seq, j);
- kmerLocations[kmerNumber].push_back(i);
- }
+ if(seenBefore[kmerNumber] == 0){
+ kmerLocations[kmerNumber].push_back(i); // ...insert the sequence index into kmerLocations for
+ } // the appropriate kmer number
+ seenBefore[kmerNumber] = 1;
+ }
}
- ofstream kmerFile(kmerDBName.c_str(), ios::trunc);
- if(!kmerFile) {
- cerr << "Error: Could not open " << kmerDBName << endl;
- exit(1);
- }
+ ofstream kmerFile; // once we have the kmerLocations folder print it out
+ openOutputFile(kmerDBName, kmerFile); // to a file
- for(int i=0;i<maxKmer;i++){
- kmerFile << i << ' ' << kmerLocations[i].size();
- for(int j=0;j<kmerLocations[i].size();j++){
- kmerFile << ' ' << kmerLocations[i][j];
+ for(int i=0;i<maxKmer;i++){ // step through all of the possible kmer numbers
+ kmerFile << i << ' ' << kmerLocations[i].size(); // print the kmer number and the number of sequences with
+ for(int j=0;j<kmerLocations[i].size();j++){ // that kmer. then print out the indices of the sequences
+ kmerFile << ' ' << kmerLocations[i][j]; // with that kmer.
}
kmerFile << endl;
}
void KmerDB::readKmerDB(string kmerDBName, ifstream& kmerDBFile){
- kmerDBFile.seekg(0);
+ kmerDBFile.seekg(0); // start at the beginning of the file
string seqName;
int seqNumber;
- for(int i=0;i<numSeqs;i++){
- int numValues;
+ for(int i=0;i<maxKmer;i++){
+ int numValues;
kmerDBFile >> seqName >> numValues;
- for(int j=0;j<numValues;j++){
- kmerDBFile >> seqNumber;
- kmerLocations[i].push_back(seqNumber);
+ for(int j=0;j<numValues;j++){ // for each kmer number get the...
+ kmerDBFile >> seqNumber; // 1. number of sequences with the kmer number
+ kmerLocations[i].push_back(seqNumber); // 2. sequence indices
}
}
kmerDBFile.close();
projects / mothur.git / blobdiff