package ca.pfv.spmf.algorithms.sequentialpatterns.prefixSpan_AGP.items;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
/**
* This class represents a sequence from a projected database (as based in PrefixSpan).
* Since it is a projected sequence, it makes reference to the original sequence.
*
* This class is inspired in SPMF PrefixSpan implementation.
*
* Copyright Antonio Gomariz Peñalver 2013
*
* This file is part of the SPMF DATA MINING SOFTWARE
* (http://www.philippe-fournier-viger.com/spmf).
*
* SPMF is free software: you can redistribute it and/or modify it under the
* terms of the GNU General Public License as published by the Free Software
* Foundation, either version 3 of the License, or (at your option) any later
* version.
*
* SPMF is distributed in the hope that it will be useful, but WITHOUT ANY
* WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
* A PARTICULAR PURPOSE. See the GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License along with
* SPMF. If not, see timeShift = new ArrayList();
/**
* Sequence where the different projections of the pseudosequence refer
*/
private Sequence sequence;
/**
* List with the first itemset where each projection starts
*/
private List firstItemset = new ArrayList();
/**
* List with the first item where each projection starts
*/
private List firstItem = new ArrayList();
/**
* It make a pseudosequence from a previous pseudosequence. Therefore, we
* are making a projection in a previous projection and we have to take into
* account the previous index of that projection to establish the ours.
* @param timeShift The time shift of the new pseudosequence
* @param pseudosequence The pseudosequence where we make another projection
* @param itemsetIndex The itemset index where our new projection is starting
* @param itemIndex The item index where our new projection is starting
* @param firstItemset An index that indicates in which projection of the
* previous pseudoseuqence we are making the new pseudosequence
*/
public PseudoSequence(long timeShift, PseudoSequence pseudosequence, int itemsetIndex, int itemIndex, int firstItemset) {
//We point to the same original sequence
this.sequence = pseudosequence.sequence;
/*We define the new time shift, that is the timeshift given plus the
* value that the given pseudosequence has. Then we add it to the list
* in its corresponding position
*/
long newTimeShift = timeShift+pseudosequence.timeShift.get(firstItemset);
this.timeShift.add(newTimeShift);
/*
* We establish the first itemset of the projection in absolute terms.
* We have to add the given itemset index to the first itemset index
* kept in the given pseudosequence
*/
this.firstItemset.add(itemsetIndex + pseudosequence.firstItemset.get(firstItemset));
//If our itemset index is the same that the given pseudosequence had
if (this.firstItemset.get(0) == pseudosequence.firstItemset.get(firstItemset)) {
//We compute our first item index from the previous one
this.firstItem.add(itemIndex + pseudosequence.firstItem.get(firstItemset));
} else {
//Otherwise, our first item index is just the given parameter
this.firstItem.add(itemIndex);
}
}
/**
* PseudoSequence made from a starndard sequence. Its purpose is make possible
* the later projections
* @param timeShift The original timeshift (Normally, it will be 0)
* @param sequence The original standard sequence
* @param itemsetIndex The itemset index where the projection it starts
* @param itemIndex The item index where the projection it starts
*/
public PseudoSequence(long timeShift, Sequence sequence, int itemsetIndex, int itemIndex) {
this.timeShift.add(timeShift);
this.sequence = sequence;
this.firstItemset.add(itemsetIndex);
this.firstItem.add(itemIndex);
}
/**
* Method to make a projection in a pseudosequence already projected.
* In this way, for a same pseudosequence, we can have several
* projections. For example, let us think in a sequence A = (a) (a b) (a b c).
* If we project by item a, we obtain three different projections:
* 1) (a b) (a b c)
* 2) (*b) (a b c)
* 3) (*b c)
* That we do is to put all the three projections in the same pseudoseuqence,
* and we refers each projection with an index. We call to every projection,
* projection point.
* @param firstItemset The projection point of the given pseudosequence
* where we are making our new projection
* @param timeShift The given timeshift for our projection
* @param pseudosequence The given pseudosequence where we are making our
* projection
* @param itemsetIndex The itemset index where our projection it starts
* @param itemIndex The item index where our projection it starts
*/
public void addProjectionPoint(int firstItemset, long timeShift, PseudoSequence pseudosequence,int itemsetIndex, int itemIndex) {
/*
* We update the timeshift from the given pseudosequence time shift and,
* them we keep it
*/
long newTimeShift = timeShift+pseudosequence.timeShift.get(firstItemset);
this.timeShift.add(newTimeShift);
/*
* We establish the starting itemset index (for our projection), from the
* previous starting itemset index
*/
this.firstItemset.add(itemsetIndex + pseudosequence.firstItemset.get(firstItemset));
//If our itemset index is the same index in the previous pseudosequence
if (this.firstItemset.get(this.firstItemset.size()-1) == pseudosequence.firstItemset.get(firstItemset)) {
//We compose the item index from the previous one
this.firstItem.add(itemIndex + pseudosequence.firstItem.get(firstItemset));
} else {
//Otherwise we simply use the given item index
this.firstItem.add(itemIndex);
}
}
/**
* It returns the first itemset of the projection, in absolute terms
* @param index the ith projection in which we want to know the first itemset
* @return the item at position index in the first itemset
*/
public int getFirstItemset(int index){
return this.firstItemset.get(index);
}
/**
* It returns the size for the current pseudosequence
* @param i the ith projection in which we want to know the size
* @return the size
*/
public int size(int i) {
int size = sequence.size() - firstItemset.get(i);
return size;
}
/**
* It returns the number of projections included in this pseudosequence
* @return the number of projections
*/
public int numberOfProjectionsIncluded() {
return firstItemset.size();
}
/**
* It returns the size of the itemset in a specified projection of the
* sequence
* @param firstItemset the ith projection in which we are interested
* @param index The ith itemset of the current pseudosequence
* @return the size
*/
public int getSizeOfItemsetAt(int firstItemset, int index) {
//we get the itemset size in the original standard sequence
int size = sequence.getItemsets().get(index + this.firstItemset.get(firstItemset)).size();
//And if that itemset if where the projection starts
if (isFirstItemset(index)) {
//We substract the starting index
size -= firstItem.get(firstItemset);
}
return size;
}
/**
* It returns the first item of the first itemset of the specified projection
* @param firstItem the specified projection in which we are interested
* @param itemsetIndex the itemset of the pseudosequence in which we are interested
* @return the item
*/
public int getBeginningOfItemset(int firstItem, int itemsetIndex){
if(isFirstItemset(itemsetIndex)){
return this.firstItem.get(firstItem);
}
return 0;
}
/**
* It informs if a projection it starts in the midle of an itemset
* @param firstItem The projection in which we are interested
* @param itemsetIndex The itemset to study
* @return true if it does. otherwise, false.
*/
public boolean isPostfix(int firstItem, int itemsetIndex) {
return isFirstItemset(itemsetIndex) && this.firstItem.get(firstItem) != 0;
}
/**
* To know if an itemset is the first one
* @param index the position of the itemset
* @return true if it is the first one, otherwise false
*/
public boolean isFirstItemset(int index) {
return index == 0;
}
/**
* Get a given item of an itemset
* @param firstItem The projection in which are interested
* @param itemIndex The item index
* @param itemsetIndex The itemset index
* @return the item
*/
public Item getItemAtInItemsetAt(int firstItem, int itemIndex, int itemsetIndex) {
if (isFirstItemset(itemsetIndex)) {
return getItemset(itemsetIndex, firstItem).get(itemIndex + this.firstItem.get(firstItem));
} else {
return getItemset(itemsetIndex, firstItem).get(itemIndex);
}
}
/**
* It returns the timestamp of an itemset in the current pseudosequence
* @param itemsetIndex the itemset index that we want to know its timestamp
* @param firstItemset The projection of the pseudosequence in which we are
* interested
* @return
*/
private long getTimeStamp(int itemsetIndex, int firstItemset) {
return getItemset(itemsetIndex, firstItemset).getTimestamp() - timeShift.get(firstItemset);
}
/**
* It obtains the original timestamp for that itemset
* @param itemsetIndex the itemset index for the pseudosequence
* @param firstItemset the projection in which we are interested
* @return the timestamp
*/
public long getAbsoluteTimeStamp(int itemsetIndex, int firstItemset) {
return getItemset(itemsetIndex, firstItemset).getTimestamp();
}
/**
* It obtains the relative timestamp
* @param itemsetIndex the itemset index
* @param firstItemset the projection in which we are interested
* @return the timestamp
*/
public long getRelativeTimeStamp(int itemsetIndex, int firstItemset) {
return getTimeStamp(itemsetIndex,firstItemset);
}
/**
* It gets the itemset in the original sequence.
* @param itemsetIndex the itemset index
* @param firstitemset the projection in which we are interested
* @return the itemset
*/
public Itemset getItemset(int itemsetIndex, int firstitemset) {
return sequence.get(itemsetIndex + firstItemset.get(firstitemset));
}
/**
* Get the pseudosequence ID
* @return the ID
*/
public int getId() {
return sequence.getId();
}
/**
* Get the string representation of this pseudosequence
* @return the string representation
*/
@Override
public String toString() {
StringBuilder r = new StringBuilder();
for (int k = 0; k < firstItemset.size(); k++) {
for (int i = 0; i < size(k); i++) {
r.append("{t=");
r.append(getTimeStamp(i, k));
r.append(", ");
for (int j = 0; j < getSizeOfItemsetAt(k, i); j++) {
r.append(getItemAtInItemsetAt(k, j, i).toString());
if (isPostfix(k, i)) {
r.append('*');
}
r.append(' ');
}
r.append("}");
}
r.append("\n");
}
return r.toString();
}
/**
* It returns the index where an item appears in the specified itemset of the
* specified projection of the current pseudosequence. If the item does not
* appear, it returns -1.
* @param firstItemset the index of the firstItemset to search
* @param itemsetIndex the current itemset index
* @param item the item
* @return the index or -1 if the item does not appear
*/
public int indexOf(int firstItemset, int itemsetIndex, Item item) {
//We get the itemset
Itemset itemset = getItemset(itemsetIndex,firstItemset);
//We get its starting point with respect to the original itemset
int beginning = getBeginningOfItemset(firstItemset, itemsetIndex);
//We search for the item
List items=itemset.getItems();
int i= Collections.binarySearch(items,item);
//If the index exist, and it does not appear before the beginning
if(i>=beginning) {
//we return it, substracting the beinning of the itemset
return i-beginning;
}
//Otherwise we return -1
return -1;
}
/**
* It gets the timeShift for a specified projection of the pseudosequence
* @param firstItemset the projection in which we are interested
* @return the timeshift
*/
public long getTimeShift(int firstItemset) {
return timeShift.get(firstItemset);
}
}
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