def selection(collumn, field, mustEqual, data):
newRelation = toyRelation.Relation()
for item in data.getRows():
if (field in item[collumn].dic):
if (item[collumn].dic[field] == mustEqual):
newRelation.addRow(item)
return newRelation
def projection(attribute,
data): #attribute retains a trailing whitespace, gotta fix
newRelation = toyRelation.Relation()
attribute = attribute[:-1] #[:-1] for trailing whitespace
if attribute != "*":
for row in data.getRows():
#print(row[attribute])
newRelation.addRow({attribute: row[attribute]})
else:
newRelation = data
return newRelation
def expandIn(target,source,relation,graph):
newRelation = toyRelation.Relation()
for row in relation.getRows():
if target in row:
for edge in toyGraph.findInGoingEdges(row[target],graph[1]):
newRow = copy.deepcopy(row)
yxCollumn = source + target #the middle collumn in : X| YX | Y
newRow[yxCollumn] = edge
newRow[source] = edge.source
newRelation.addRow(newRow)
return newRelation
def expandOut(source,target,relation,graph):
newRelation = toyRelation.Relation()
for row in relation.getRows():
if source in row:
for edge in toyGraph.findOutGoingEdges(row[source],graph[1]):
newRow = copy.deepcopy(row)
xyCollumn = source + target #the middle collumn in : X| XY | Y
newRow[xyCollumn] = edge
newRow[target] = edge.target
newRelation.addRow(newRow)
return newRelation
def hashJoin(table1, table2, index1, index2):
h = defaultdict(list)
# hash phase
for s in table1.getRows():
h[s[index1].iden].append(s)
newRelation = toyRelation.Relation()
for r in table2.getRows():
for s in (h[r[index2].iden]):
r.update(s)
newRelation.addRow(r)
return newRelation
def getNodes(argument,graph):
newRelation = toyRelation.Relation()
for node in graph[0]:
newRelation.addRow({argument : node})
return newRelation