def find_frequent_itemsets(transactions, minimum_support, include_support=False):
#This will have items in the sorted order that will help finding Ored FreqItemsets
global itemsAvail
global noOfTransactions
"""
Find frequent itemsets in the given transactions using FP-growth. This
function returns a generator instead of an eagerly-populated list of items.
The `transactions` parameter can be any iterable of iterables of items.
`minimum_support` should be an integer specifying the minimum number of
occurrences of an itemset for it to be accepted.
Each item must be hashable (i.e., it must be valid as a member of a
dictionary or a set).
If `include_support` is true, yield (itemset, support) pairs instead of
just the itemsets.
"""
processed_transactions = []
global itemSupport
# Load the passed-in transactions and count the support that individual
# items have.
for transaction in transactions:
noOfTransactions += 1
processed = []
for item in transaction:
if item not in itemsAvail:
itemsAvail.append(item)
itemSupport[item] += 1
processed.append(item)
processed_transactions.append(processed)
#Sorting the list of items
itemsAvail.sort(key=lambda v: itemSupport[v], reverse=False)
#Updating itemsAvailIndex
for i in range(0,len(itemsAvail)):
itemsAvailIndex[itemsAvail[i]] = i
# Remove infrequent items from the item support dictionary.
#itemSupport = dict((item, support) for item, support in itemSupport.iteritems()
#if support >= minimum_support)
# Build our FP-tree. Before any transactions can be added to the tree, they
# must be stripped of infrequent items and their surviving items must be
# sorted in decreasing order of frequency.
master = FPTree()
#Runs clean_transaction on every processed_transactions and returns as a tuple
for transaction in imap(clean_transaction, processed_transactions):
master.add(transaction)
#Can Further Check for Confidence Values
supportedItemSets = []
for itemset in find_with_suffix(master, [], minimum_support):
supportedItemSets.append(itemset)
return supportedItemSets,master,itemSupport
def conditional_tree_from_paths(paths, minimum_support):
"""Builds a conditional FP-tree from the given prefix paths."""
tree = FPTree()
condition_item = None
items = set()
# Import the nodes in the paths into the new tree. Only the counts of the
# leaf notes matter; the remaining counts will be reconstructed from the
# leaf counts.
for path in paths:
if condition_item is None:
condition_item = path[-1].item
point = tree.root
for node in path:
next_point = point.search(node.item)
if not next_point:
# Add a new node to the tree.
items.add(node.item)
count = node.count if node.item == condition_item else 0
next_point = FPNode(tree, node.item, count)
point.add(next_point)
tree._update_route(next_point)
point = next_point
assert condition_item is not None
# Calculate the counts of the non-leaf nodes.
for path in tree.prefix_paths(condition_item):
count = path[-1].count
for node in reversed(path[:-1]):
node._count += count
# Eliminate the nodes for any items that are no longer frequent.
for item in items:
support = sum(n.count for n in tree.nodes(item))
if support < minimum_support:
# Doesn't make the cut anymore
for node in tree.nodes(item):
if node.parent is not None:
node.parent.remove(node)
# Finally, remove the nodes corresponding to the item for which this
# conditional tree was generated.
for node in tree.nodes(condition_item):
if node.parent is not None: # the node might already be an orphan
node.parent.remove(node)
return tree
