/// <summary>
/// Generates a knowledge structure (KStructure object) from a ranked order (RankOrder object) by applying Rule 1.
/// </summary>
///
/// <param name="rankOrder">RankOrder object that is used to generate a knowledge structure.</param>
///
/// <returns>KStructure object, or null if error occured.</returns>
public KStructure createKStructure(RankOrder rankOrder)
{
// Implements Rule 1: Given a set GR of problems with a rank R and a set G<R of problems of lower ranks,
// a union of any subset of GR with G<R is a knowledge state.
// [SC] make sure the rankOrder object is not null
if (rankOrder == null)
{
Log(Severity.Error, "createKStructure: Null object is passed as RankOrder parameter. Returning null.");
return(null);
}
// [SC] make sure there is at least one rank in the rank order
if (rankOrder.getRankCount() == 0)
{
Log(Severity.Error, "createKStructure: rank order has no ranks. Returning null.");
return(null);
}
// [SC] make sure the ranks are sorted in an ascending order
rankOrder.sortAscending();
// [SC] creating knowledge states
List <KState> allStates = new List <KState>();
List <PCategory> prevCategories = new List <PCategory>();
foreach (Rank rank in rankOrder.getRanks())
{
// [SC] getting all unique subsets of categories in this rank
List <List <PCategory> > subsets = rank.getSubsets();
// [SC] for each subset, create a knowledge state by combining with all categories of lower ranks
foreach (List <PCategory> subset in subsets)
{
KState state = new KState();
foreach (PCategory category in prevCategories)
{
state.addCategory(category);
}
foreach (PCategory category in subset)
{
state.addCategory(category);
}
allStates.Add(state);
}
prevCategories.AddRange(rank.getCategories());
}
// [SC] sort states by their sizes in an ascending order
allStates.Sort((stateOne, stateTwo) => stateOne.getCategoryCount().CompareTo(stateTwo.getCategoryCount()));
// [SC] creating an empty knowledge structure object
KStructure ks = new KStructure(rankOrder);
// [SC] creating 0th rank with an empty root state
int rankIndex = 0;
int stateCounter = 0; // [SC] used to generate an ID for each state
KSRank prevRank = null;
KSRank currRank = new KSRank(rankIndex); // [SC] the root rank will automatically add an empty root state
ks.addRank(currRank);
// [SC] adding all states in respective ranks
foreach (KState state in allStates)
{
if (state.getCategoryCount() > rankIndex)
{
stateCounter = 0;
prevRank = currRank;
currRank = new KSRank(++rankIndex);
ks.addRank(currRank);
}
if (currRank.addState(state))
{
state.Id = KSGenerator.getStateID(rankIndex, ++stateCounter);
foreach (KState prevState in prevRank.getStates())
{
if (prevState.isSubsetOf(state))
{
prevState.addNextState(state);
state.addPrevState(prevState);
}
}
}
}
return(ks);
}
/// <summary>
/// Deserializes XML into KStructure object
/// </summary>
///
/// <param name="doc">XDocument instance</param>
///
/// <returns>KStructure object</returns>
public KStructure createKStructure(XDocument doc)
{
// [TODO] validate against schema
XName[] nodeNames;
// [SC] a hash table of all categories
Dictionary <string, PCategory> categories = new Dictionary <string, PCategory>();
// [SC] a hash table of all states
Dictionary <string, KState> states = new Dictionary <string, KState>();
// [SC] iterate through 'TwoA/PCategories/PCategory' elements
nodeNames = new XName[] { XMLFactory.PCATS_ELEM, XMLFactory.PCAT_ELEM };
foreach (XElement categoryElem in SelectNodes(doc.Root, nodeNames))
{
// [SC] get the value of 'TwoA/PCategories/PCategory@xsd:id' attribute
string id = categoryElem.Attribute(XMLFactory.ID_ATTR).Value;
// [SC] get the value of 'TwoA/PCategories/PCategory/Rating' element
double rating;
if (!Double.TryParse(categoryElem.Element(XMLFactory.RATING_ELEM).Value, out rating))
{
Log(Severity.Error, String.Format("createKStructure: unable to parse rating for category {0}. Returning null.", id));
return(null); // [TODO] no need due to schema check?
}
PCategory category = new PCategory(id, rating);
categories.Add(id, category);
}
RankOrder rankOrder = new RankOrder();
// [SC] parse the value of 'TwoA/RankOrder/Params/Threshold' element
nodeNames = new XName[] { XMLFactory.RANKORDER_ELEM, XMLFactory.PARAMS_ELEM, XMLFactory.THRESHOLD_ELEM };
double threshold;
if (Double.TryParse(SelectSingleNode(doc.Root, nodeNames).Value, out threshold))
{
rankOrder.Threshold = threshold;
}
else
{
Log(Severity.Error, "createKStructure: unable to parse the threshold value. Returning null value. Returning null.");
return(null); // [TODO] no need due to schema check?
}
// [SC] iterate through 'TwoA/RankOrder/Ranks/Rank' elements
nodeNames = new XName[] { XMLFactory.RANKORDER_ELEM, XMLFactory.RANKS_ELEM, XMLFactory.RANK_ELEM };
foreach (XElement rankElem in SelectNodes(doc.Root, nodeNames))
{
Rank rank = new Rank();
// [SC] parse the value of 'TwoA/RankOrder/Ranks/Rank@Index' atttribute
int rankIndex;
if (Int32.TryParse(rankElem.Attribute(XMLFactory.INDEX_ATTR).Value, out rankIndex))
{
rank.RankIndex = rankIndex;
}
else
{
Log(Severity.Error, "createKStructure: unable to parse the index of a rank in the rank order. Returning null.");
return(null); // [TODO] no need due to schema check?
}
// [SC] iterate through 'TwoA/RankOrder/Ranks/Rank/PCategory' elements
foreach (XElement categoryElem in rankElem.Elements(XMLFactory.PCAT_ELEM))
{
// [SC] parse 'TwoA/RankOrder/Ranks/Rank/PCategory@xsd:idref' attribute
if (categoryElem.Attribute(XMLFactory.IDREF_ATTR) == null)
{
Log(Severity.Error, String.Format("createKStructure: unable to parse ID for a category in rank {0} of the rank order. Returning null.", rankIndex));
return(null); // [TODO] no need due to schema check?
}
string id = categoryElem.Attribute(XMLFactory.IDREF_ATTR).Value;
// [SC] retrieve PCategory object by its id and add it to the rank object
PCategory category = categories[id];
if (category == null)
{
Log(Severity.Error
, String.Format("createKStructure: category {0} from rank {1} of rank order is not found in the list of categories. Returning null."
, id, rankIndex));
return(null); // [TODO] no need due to schema check?
}
rank.addCategory(category);
}
rankOrder.addRank(rank);
}
KStructure kStructure = new KStructure(rankOrder);
// [SC] iterate through 'TwoA/KStructure/KSRank' elements
nodeNames = new XName[] { XMLFactory.KSTRUCTURE_ELEM, XMLFactory.KSRANK_ELEM };
foreach (XElement ksrankElem in SelectNodes(doc.Root, nodeNames))
{
KSRank ksrank = new KSRank();
// [SC] parse the value of 'TwoA/KStructure/KSRank@Index' attribute
int rankIndex;
if (Int32.TryParse(ksrankElem.Attribute(XMLFactory.INDEX_ATTR).Value, out rankIndex))
{
ksrank.RankIndex = rankIndex;
}
else
{
Log(Severity.Error, "createKStructure: unable to parse index of a rank in the knowledge structure. Returning null.");
return(null); // [TODO] no need due to schema check?
}
if (rankIndex == 0)
{
XElement rootStateElem = ksrankElem.Element(XMLFactory.KSTATE_ELEM);
// [SC] parse 'TwoA/KStructure/KSRank/KState@xsd:id' attribute
if (rootStateElem.Attribute(XMLFactory.ID_ATTR) == null)
{
Log(Severity.Error, "createKStructure: unable to parse ID of the root state in the knowledge structure. Returning null.");
return(null); // [TODO] no need due to schema check?
}
ksrank.getStateAt(0).Id = rootStateElem.Attribute(XMLFactory.ID_ATTR).Value;
states.Add(ksrank.getStateAt(0).Id, ksrank.getStateAt(0));
kStructure.addRank(ksrank);
continue;
}
// [SC] iterate through 'TwoA/KStructure/KSRank/KState' elements
foreach (XElement stateElem in ksrankElem.Elements(XMLFactory.KSTATE_ELEM))
{
KState kstate = new KState();
// [SC] parse 'TwoA/KStructure/KSRank/KState@xsd:id' attribute
if (stateElem.Attribute(XMLFactory.ID_ATTR) == null)
{
Log(Severity.Error, String.Format("createKStructure: unable to parse ID of a state in the rank {0} of the knowledge structure. Returning null.", rankIndex));
return(null); // [TODO] no need due to schema check?
}
kstate.Id = stateElem.Attribute(XMLFactory.ID_ATTR).Value;
// [SC] parse 'TwoA/KStructure/KSRank/KState@Type' attribute
if (stateElem.Attribute(XMLFactory.TYPE_ATTR) == null)
{
Log(Severity.Error, String.Format("createKStructure: unable to parse state type in the rank {0} of the knowledge structure. Returning null.", rankIndex));
return(null); // [TODO] no need due to schema check?
}
kstate.StateType = stateElem.Attribute(XMLFactory.TYPE_ATTR).Value;
// [SC] iterate through 'TwoA/KStructure/KSRank/KState/PCategories/PCategory' elements
nodeNames = new XName[] { XMLFactory.PCATS_ELEM, XMLFactory.PCAT_ELEM };
foreach (XElement categoryElem in SelectNodes(stateElem, nodeNames))
{
// [SC] parse 'TwoA/KStructure/KSRank/KState/PCategories/PCategory@xsd:idref' attribute
if (categoryElem.Attribute(XMLFactory.IDREF_ATTR) == null)
{
Log(Severity.Error, String.Format("createKStructure: unable to parse ID of a category in the state {0}. Returning null.", kstate.Id));
return(null); // [TODO] no need due to schema check?
}
string id = categoryElem.Attribute(XMLFactory.IDREF_ATTR).Value;
// [SC] retrieve PCategory object by its id and add it to the rank object
PCategory category = categories[id];
if (category == null)
{
Log(Severity.Error
, String.Format("createKStructure: category {0} from the state {1} is not found in the list of categories. Returning null."
, id, kstate.Id));
return(null); // [TODO] no need due to schema check?
}
kstate.addCategory(category);
}
// [SC] iterate through 'TwoA/KStructure/KSRank/KState/PreviousStates/KState' elements
nodeNames = new XName[] { XMLFactory.PREV_STATES_ELEM, XMLFactory.KSTATE_ELEM };
foreach (XElement prevStateElem in SelectNodes(stateElem, nodeNames))
{
// [SC] parse 'TwoA/KStructure/KSRank/KState/PreviousStates/KState@xsd:idref' attribute
if (prevStateElem.Attribute(XMLFactory.IDREF_ATTR) == null)
{
Log(Severity.Error, String.Format("createKStructure: unable to parse ID of a previous state for a state {0}. Returning null.", kstate.Id));
return(null); // [TODO] no need due to schema check?
}
string id = prevStateElem.Attribute(XMLFactory.IDREF_ATTR).Value;
// [SC] retrieve prev state object by its id and add it to the current state object
KState prevState = states[id];
if (prevState == null)
{
Log(Severity.Error, String.Format("createKStructure: unable to find previously created state object with id '{0}'. Returning null.", id));
return(null); // [TODO] no need due to schema check?
}
kstate.addPrevState(prevState);
prevState.addNextState(kstate);
}
states.Add(kstate.Id, kstate);
ksrank.addState(kstate);
}
kStructure.addRank(ksrank);
}
return(kStructure);
}
/// <summary>
/// Expands the specified knowledge structure with new states by applying Rule 2.
/// </summary>
///
/// <param name="ks">Knowledge structure to be expanded with new states.</param>
///
/// <returns>Expanded knowledge structure</returns>
public void createExpandedKStructure(KStructure ks)
{
// Implements Rule 2: Given a set GR of problems with a rank R and a set GR-1 of problems with rank R-1,
// a union of any subset of GR with any knowledge state KR-1 containing at least one problem from GR-1 is a state.
// [SC] make sure the knowledge structure object is not null
if (ks == null)
{
Log(Severity.Error, "createExpandedKStructure: KStructure object is null. Returning from method.");
return;
}
// [SC] make sure the rank order of categories is available
if (!ks.hasRankOrder())
{
Log(Severity.Error, "createExpandedKStructure: KStructure object contains no rank order. Returning from method.");
return;
}
// [SC] make sure the knowledge structure has ranks
if (!ks.hasRanks())
{
Log(Severity.Error, "createExpandedKStructure: KStructure object contains no ranks with states. Returning from method.");
return;
}
Rank prevRank = null;
foreach (Rank rank in ks.rankOrder.getRanks())
{
if (prevRank != null)
{
// [SC] getting all unique subsets of categories in this rank
List <List <PCategory> > subsets = rank.getSubsets();
// [SC] retrieve all KS ranks with minimum required state size
List <KSRank> ksRanks = ks.getRanks().FindAll(rankOne => rankOne.RankIndex >= prevRank.RankIndex);
if (ksRanks == null || ksRanks.Count == 0)
{
continue;
}
// [SC] this list contains all relevant states that contain any category from GR-1
List <KState> states = new List <KState>();
foreach (KSRank ksRank in ksRanks)
{
// [SC] From given KS rank, retrieve all states that contain at least one problem from GR-1 and add them to the common list
states.AddRange(ksRank.getStates().FindAll(stateOne => stateOne.getCategories().Intersect(prevRank.getCategories()).Any()));
}
if (states.Count == 0)
{
continue;
}
// [SC] iterate through subsets of GR
foreach (List <PCategory> subset in subsets)
{
foreach (KState state in states)
{
// [SC] if state already contains the entire subset then skip it
if (state.getCategories().Intersect(subset).Count() == subset.Count)
{
continue;
}
// [SC] creating a new state
KState newState = new KState(KSGenerator.EXPANDED_STATE);
foreach (PCategory category in state.getCategories())
{
newState.addCategory(category);
}
foreach (PCategory category in subset)
{
newState.addCategory(category);
}
// [SC] add the new state to the respective rank
KSRank newStateRank = ks.getRanks().Find(rankOne => rankOne.RankIndex == newState.getCategoryCount());
if (newStateRank.addState(newState))
{
newState.Id = KSGenerator.getStateID(newStateRank.RankIndex, newStateRank.getStateCount());
// [SC] link the new state with previous states of lower rank
KSRank prevStateRank = ks.getRanks().Find(rankOne => rankOne.RankIndex == newState.getCategoryCount() - 1);
if (prevStateRank != null)
{
foreach (KState prevState in prevStateRank.getStates())
{
if (prevState.isSubsetOf(newState))
{
prevState.addNextState(newState);
newState.addPrevState(prevState);
}
}
}
// [SC] link the new state with next states of higher rank
KSRank nextStateRank = ks.getRanks().Find(rankOne => rankOne.RankIndex == newState.getCategoryCount() + 1);
if (nextStateRank != null)
{
foreach (KState nextState in nextStateRank.getStates())
{
if (newState.isSubsetOf(nextState))
{
nextState.addPrevState(newState);
newState.addNextState(nextState);
}
}
}
}
}
}
}
prevRank = rank;
}
}
/// <summary>
/// creates an XML document object from a given KStructure object
/// </summary>
///
/// <param name="kStructure">KStructure object with a rank order and knowledge structure</param>
///
/// <returns>XmlDocument object</returns>
public XDocument createXml(KStructure kStructure)
{
// [SC] verifying that KStructure object is not null
if (kStructure == null)
{
Log(Severity.Error, "Unable to transform knowledge structure into XML format. kStructure parameter is null. Returning null.");
return(null);
}
// [SC] create xml document object
XDocument doc = new XDocument();
// [SC] add xml declaration to the document
doc.Declaration = new XDeclaration("1.0", "UTF-8", "yes");
// [SC] add a root element 'TwoA' and declare namespace attributes
XElement twoAElem = new XElement(XMLFactory.TWOA_ELEM
, new XAttribute(XMLFactory.XMLNS_ATTR, XMLFactory.twoa)
, new XAttribute(XMLFactory.XSD_ATTR, XMLFactory.xsd)
);
doc.Add(twoAElem);
// [SC] create a list of categories and a rank order
if (kStructure.hasRankOrder())
{
RankOrder rankOrder = kStructure.rankOrder;
rankOrder.sortAscending();
// [SC] add 'TwoA/PCategories' list element
XElement pcatsElem = new XElement(XMLFactory.PCATS_ELEM);
twoAElem.Add(pcatsElem);
// [SC] add 'TwoA/RankOrder' element
XElement rankOrderElem = new XElement(XMLFactory.RANKORDER_ELEM);
twoAElem.Add(rankOrderElem);
// [SC] add 'TwoA/RankOrder/Params' list element
XElement rankParamsElem = new XElement(XMLFactory.PARAMS_ELEM);
rankOrderElem.Add(rankParamsElem);
// [SC] add 'TwoA/RankOrder/Params.Threshold' element
XElement thresholdElem = new XElement(XMLFactory.THRESHOLD_ELEM);
rankParamsElem.Add(thresholdElem);
thresholdElem.SetValue("" + rankOrder.Threshold);
// [SC] create 'TwoA/RankOrder/Ranks' list element
XElement ranksElem = new XElement(XMLFactory.RANKS_ELEM);
rankOrderElem.Add(ranksElem);
// [SC] iterate through ranks and create correspoinding XML elements
for (int rankCounter = 0; rankCounter < rankOrder.getRankCount(); rankCounter++)
{
Rank rank = rankOrder.getRankAt(rankCounter);
// [SC] add 'TwoA/RankOrder/Ranks/Rank' element
XElement rankElem = new XElement(XMLFactory.RANK_ELEM);
ranksElem.Add(rankElem);
// [SC] add 'TwoA/RankOrder/Ranks/Rank@Index' attribute to the 'Rank' element
XAttribute indexAttr = new XAttribute(XMLFactory.INDEX_ATTR, "" + rank.RankIndex);
rankElem.Add(indexAttr);
// [SC] interate through categories in the rank and create corresponding XML element and reference to it
for (int catCounter = 0; catCounter < rank.getCategoryCount(); catCounter++)
{
PCategory pcat = rank.getCategoryAt(catCounter);
// [SC] add 'TwoA/PCategories/PCategory' element with 'xsd:id' attribute
XElement pcatElem = new XElement(XMLFactory.PCAT_ELEM);
pcatsElem.Add(pcatElem);
// [SC] add 'TwoA/PCategories/PCategory@xsd:id' attribute
XAttribute idAttr = new XAttribute(XMLFactory.ID_ATTR, "" + pcat.Id);
pcatElem.Add(idAttr);
// [SC] add 'TwoA/PCategories/PCategory/Rating' element
XElement ratingElem = new XElement(XMLFactory.RATING_ELEM);
pcatElem.Add(ratingElem);
ratingElem.SetValue("" + pcat.Rating);
// [SC] add 'TwoA/RankOrder/Ranks/Rank/PCategory' element with 'xsd:idref' attribute
XElement pcatRefElem = new XElement(XMLFactory.PCAT_ELEM);
rankElem.Add(pcatRefElem);
// [SC] add 'TwoA/RankOrder/Ranks/Rank/PCategory@xsd:idref' attribute
XAttribute idrefAttr = new XAttribute(XMLFactory.IDREF_ATTR, "" + pcat.Id);
pcatRefElem.Add(idrefAttr);
}
}
}
else
{
Log(Severity.Warning, "Rank order is missing while transforming KStructure object into XML format.");
}
// [SC] creates elements for 'KStructure'
if (kStructure.hasRanks())
{
kStructure.sortAscending();
// [SC] add 'TwoA/KStructure' element
XElement kStructureElem = new XElement(XMLFactory.KSTRUCTURE_ELEM);
twoAElem.Add(kStructureElem);
// [SC] iterate through KSRanks and create corresponding XML elements
for (int rankCounter = 0; rankCounter < kStructure.getRankCount(); rankCounter++)
{
KSRank rank = kStructure.getRankAt(rankCounter);
// [SC] add 'TwoA/KStructure/KSRank' element
XElement ksRankElem = new XElement(XMLFactory.KSRANK_ELEM);
kStructureElem.Add(ksRankElem);
// [SC] add 'TwoA/KStructure/KSRank@Index' attribute
XAttribute indexAttr = new XAttribute(XMLFactory.INDEX_ATTR, "" + rank.RankIndex);
ksRankElem.Add(indexAttr);
// [SC] iterate through states and add corresponding XML elements
for (int stateCounter = 0; stateCounter < rank.getStateCount(); stateCounter++)
{
KState state = rank.getStateAt(stateCounter);
// [SC] add 'TwoA/KStructure/KSRank/KState' element with 'xsd:id' attribute
XElement stateElem = new XElement(XMLFactory.KSTATE_ELEM);
ksRankElem.Add(stateElem);
// [SC] add 'TwoA/KStructure/KSRank/KState@xsd:id' attribute
XAttribute idAttr = new XAttribute(XMLFactory.ID_ATTR, "" + state.Id);
stateElem.Add(idAttr);
// [SC] add 'TwoA/KStructure/KSRank/KState@Type' attribute
XAttribute typeAttr = new XAttribute(XMLFactory.TYPE_ATTR, "" + state.StateType);
stateElem.Add(typeAttr);
// [SC] add 'TwoA/KStructure/KSRank/KState/PCategories' list element
XElement pcatsElem = new XElement(XMLFactory.PCATS_ELEM);
stateElem.Add(pcatsElem);
// [SC] iterate through categories in the state
for (int catCounter = 0; catCounter < state.getCategoryCount(); catCounter++)
{
PCategory pcat = state.getCategoryAt(catCounter);
// [SC] add 'TwoA/KStructure/KSRank/KState/PCategories/PCategory' element with 'xsd:idref' attribute
XElement pcatElem = new XElement(XMLFactory.PCAT_ELEM);
pcatsElem.Add(pcatElem);
// [SC] add 'TwoA/KStructure/KSRank/KState/PCategories/PCategory@xsd:idref' attribute
XAttribute idrefAttr = new XAttribute(XMLFactory.IDREF_ATTR, "" + pcat.Id);
pcatElem.Add(idrefAttr);
}
// [SC] add 'TwoA/KStructure/KSRank/KState/PreviousStates' list element
XElement prevStatesElem = new XElement(XMLFactory.PREV_STATES_ELEM);
stateElem.Add(prevStatesElem);
// [SC] iterate through immediate prerequisite states in the gradient
for (int prevStateCounter = 0; prevStateCounter < state.getPrevStateCount(); prevStateCounter++)
{
KState prevState = state.getPrevStateAt(prevStateCounter);
// [SC] add 'TwoA/KStructure/KSRank/KState/PreviousStates/KState' element with 'xsd:idref' attribute
XElement prevStateElem = new XElement(XMLFactory.KSTATE_ELEM);
prevStatesElem.Add(prevStateElem);
// [SC] add 'TwoA/KStructure/KSRank/KState/PreviousStates/KState@xsd:idref' attribute
XAttribute idrefAttr = new XAttribute(XMLFactory.IDREF_ATTR, "" + prevState.Id);
prevStateElem.Add(idrefAttr);
}
// [SC] add 'TwoA/KStructure/KSRank/KState/NextStates' list element
XElement nextStatesElem = new XElement(XMLFactory.NEXT_STATES_ELEM);
stateElem.Add(nextStatesElem);
// [SC] iterate through immediate next states in the gradient
for (int nextStateCounter = 0; nextStateCounter < state.getNextStateCount(); nextStateCounter++)
{
KState nextState = state.getNextStateAt(nextStateCounter);
// [SC] add 'TwoA/KStructure/KSRank/KState/NextStates/KState' element with 'xsd:idref' attribute
XElement nextStateElem = new XElement(XMLFactory.KSTATE_ELEM);
nextStatesElem.Add(nextStateElem);
// [SC] add 'TwoA/KStructure/KSRank/KState/NextStates/KState@xsd:idref' attribute
XAttribute idrefAttr = new XAttribute(XMLFactory.IDREF_ATTR, "" + nextState.Id);
nextStateElem.Add(idrefAttr);
}
}
}
}
else
{
Log(Severity.Warning, "Knowledge structure is missing while transforming KStructure object into XML format.");
}
return(doc);
}