def writeFile(rdd: RDD):
num = rdd.count()
if num > 0:
result_dic = open_result()
print(result_dic)
rdd_c = rdd.collect()
lst = ast.literal_eval(str(rdd_c))
for item in lst:
key = item[0]
value = item[1]
if str(key).replace("'", '') in result_dic.keys():
result_dic[str(key).replace(
"'", '')] = result_dic[str(key).replace("'", '')] + value
else:
result_dic[str(key).replace("'", '')] = value
result = open(path, 'w', encoding='utf-8')
result.write(
json.dumps(result_dic).encode('gb18030').decode('unicode_escape'))
result.close()
def writeFile(rdd: RDD, f_type):
num = rdd.count()
global save1
global save2
if num > 0:
result_dic = open_result(f_type)
rdd_c = rdd.collect()
lst = ast.literal_eval(str(rdd_c))
for item in lst:
key = item[0]
value = item[1]
if str(key).replace("'", '') in result_dic.keys():
result_dic[str(key).replace("'", '')] = result_dic[str(key).replace("'", '')] + value
else:
result_dic[str(key).replace("'", '')] = value
if f_type == 0:
save1 = result_dic
if f_type == 1:
save2 = result_dic
result = open(path[f_type], 'w', encoding='utf-8')
result.write(json.dumps(result_dic).encode('gb18030').decode('unicode_escape'))
result.close()
def pcy_for_rdd(baskets: RDD, support_threshold_total=support_threshold_total) -> list:
def check_all_subsets_frequent(itemset: list, frequent_itemsets_dict: dict) -> bool:
'''
For example, given a triple ['2', '1', '8'], check if all its subsets ['2', '1'], ['2', '8'], ['1', '8']
are frequent items.
:param itemset:
:return:
'''
itemset_size = len(itemset)
for i in range(itemset_size):
subset = itemset.copy()
subset.pop(i)
try:
_ = frequent_itemsets_dict[tuple(subset)] # 不再需要sorted这个subset，basket已sort
except:
return False
return True
num_baskets = baskets.count()
singleton_counts = baskets.\
flatMap(lambda set: [(item, 1) for item in set]).\
reduceByKey(lambda x,y: x+y).\
filter(lambda pair: pair[1] >= support_threshold_total)
# frequent_singletons_dict = dict(singleton_counts.collect()).keys()
frequent_itemsets_dict = dict(singleton_counts.collect())
# print("frequent_itemsets_dict", frequent_itemsets_dict)
frequent_itemsets_list = [sorted(list(frequent_itemsets_dict.keys()))]
del singleton_counts
gc.collect()
# all_pairs = baskets.flatMap(lambda basket: generate_combination(basket, 2)).persist() # 既然first/second pass都要用，为何不persist
#
# bucket_counts = all_pairs.map(lambda pair:(hash_pair(pair), 1)).reduceByKey(lambda x,y: x+y).collect() # first pass
# bitmap = dict(bucket_counts)
# for key, value in bitmap.items():
# if value >= support_threshold_total:
# bitmap[key] = 1
# else:
# bitmap[key] = 0
current_itemset_size = 2
while True:
# print("current_itemset_size", current_itemset_size)
# if current_itemset_size == 2: # pairs are special
# frequent_itemsets = all_pairs.\
# filter(lambda _: qualified_as_candidate_pair(_, frequent_itemsets_dict, bitmap)).\
# map(lambda pair: (tuple(pair), 1)).\
# reduceByKey(lambda x, y: x + y).\
# filter(lambda pair: pair[1] >= support_threshold_total).persist()
# del all_pairs
# gc.collect()
# else: # 双重filter
frequent_itemsets = baskets.flatMap(lambda basket: generate_combination_with_filter(basket, frequent_itemsets_dict, current_itemset_size)). \
map(lambda itemset: (tuple(itemset), 1)).\
reduceByKey(lambda x,y: x+y).\
filter(lambda pair: pair[1] >= support_threshold_total).persist()
# if frequent_itemsets.count() == 0:
# break
current_size_frequent_itemsets = sorted(frequent_itemsets.keys().collect())
if current_size_frequent_itemsets == []:
break
frequent_itemsets_list.append(current_size_frequent_itemsets)
frequent_itemsets_dict.update(dict.fromkeys(current_size_frequent_itemsets))
# frequent_itemsets_dict.update(dict(frequent_itemsets.collect()))
current_itemset_size += 1
del frequent_itemsets # 也许正确操作应该是释放内存之后再del？我不懂
del current_size_frequent_itemsets
gc.collect()
gc.collect()
return frequent_itemsets_list
def son(baskets: RDD, support_threshold_total=support_threshold_total) -> list:
def pcy_for_list(partition: list, support_threshold_total=support_threshold_total) -> dict:
# partition = baskets
num_baskets_chunk = len(partition)
support_threshold = math.ceil(support_threshold_total * num_baskets_chunk / num_baskets)
# first pass
singleton_counts = {}
bucket_counts = {}
for basket in partition:
for item in basket:
singleton_counts[item] = singleton_counts.get(item, 0) + 1
pairs = generate_combination(basket, size=2)
for pair in pairs:
key = hash_pair(pair)
bucket_counts[key] = bucket_counts.get(key, 0) + 1
for key, value in bucket_counts.items():
if value >= support_threshold:
bucket_counts[key] = 1
else:
bucket_counts[key] = 0
frequent_itemsets = {}
for key, value in singleton_counts.items():
if value >= support_threshold:
frequent_itemsets[key] = None # store all frequent singletons
# print("singleton_counts", singleton_counts)
# print("frequent singletons", frequent_itemsets)
del singleton_counts
gc.collect()
# second pass
itemset_counts = {}
for basket in partition:
pairs = generate_combination(basket, size=2)
for pair in pairs:
if qualified_as_candidate_pair(pair, frequent_itemsets, bitmap=bucket_counts):
key = tuple(pair)
itemset_counts[key] = itemset_counts.get(key, 0) + 1
for key, value in itemset_counts.items():
if value >= support_threshold:
frequent_itemsets[key] = None # store all frequent pairs
# print("pair counts", itemset_counts)
del itemset_counts
gc.collect()
# more passes for larger-size itemsets
size = 3
num_frequent_itemsets = len(frequent_itemsets)
while True:
itemset_counts = {}
for basket in partition:
itemsets = generate_combination_with_filter(basket, frequent_itemsets, size)
for itemset in itemsets:
key = tuple(itemset)
itemset_counts[key] = itemset_counts.get(key, 0) + 1
for key, value in itemset_counts.items():
if value >= support_threshold:
frequent_itemsets[key] = None # store all frequent pairs
del itemset_counts
gc.collect()
current_num_frequent_itemsets = len(frequent_itemsets)
# print("frequent_itemsets", frequent_itemsets)
if current_num_frequent_itemsets == num_frequent_itemsets: # no more new frequent itemsets
# print("break")
break
num_frequent_itemsets = current_num_frequent_itemsets
size += 1
# print("frequent_itemsets", frequent_itemsets)
return frequent_itemsets
# First stage
num_baskets = baskets.count()
candidate_itemsets = dict.fromkeys(baskets.mapPartitions(lambda _: pcy_for_list(list(_), support_threshold_total)).distinct().collect(), 0)
# print("candidate_itemsets", candidate_itemsets)
# Second stage
def qualified_as_candidate_itemset(itemset):
try:
_ = candidate_itemsets[itemset]
return True
except:
return False
singleton_counts = baskets.\
flatMap(lambda basket: basket).\
filter(lambda item: qualified_as_candidate_itemset(item)).\
map(lambda _: (_, 1)).\
reduceByKey(lambda x,y: x+y).\
filter(lambda pair: pair[1] >= support_threshold_total).keys().collect()
frequent_itemsets = [sorted(singleton_counts)]
del singleton_counts
gc.collect()
size = 2
while True:
frequent_itemsets_for_particular_size = baskets.\
flatMap(lambda _: generate_combination_with_filter(_, candidate_itemsets, size)).\
filter(lambda _: qualified_as_candidate_itemset(tuple(_))).\
map(lambda _: (tuple(_), 1)).\
reduceByKey(lambda x,y: x+y).\
filter(lambda pair: pair[1] >= support_threshold_total).keys().collect()
if frequent_itemsets_for_particular_size == []:
break
else:
frequent_itemsets.append(sorted(frequent_itemsets_for_particular_size))
size += 1
del frequent_itemsets_for_particular_size
gc.collect()
return frequent_itemsets
def kmeans(data: RDD,
num_clusters: int,
min_cluster_id=0,
max_iterations=20) -> RDD:
"""
:param data: pair RDD, key is point_id, value is feature vector
:param num_clusters: number of clusters
:param min_cluster_id: The id of each cluster is min_cluster_id, min_cluster_id + 1, min_cluster_id + 2 ...
:param max_iterations: maximum number of iterations
:return: clustering result, pair RDD, key is point_id, value is (cluster id, feature vector)
"""
# ** some helper functions:
def minimum_distance_to_centroids(point: list,
centroids: dict) -> float:
min_distance = min([
sum([(i - j)**2 for i, j in zip(point, centroid)])
for centroid in centroids
])
return min_distance
def assign_point_to_cluster(point: list, centroids_: dict) -> int:
"Given a data point, find the nearest centroid to it"
distances = [(sum([(i - j)**2
for i, j in zip(point, centroid)]), cid)
for cid, centroid in centroids_.items()]
min_distance, cluster_index = min(distances)
return cluster_index
# ** initialize the first k centroids
total_samples = data.count()
print("initializing centroids")
print("total samples:", total_samples)
sample_fraction = 0.3
if total_samples * sample_fraction < num_clusters:
if total_samples < num_clusters:
centroids = data.values().collect()
else:
centroids = data.values().take(num_clusters)
else:
sample_data = data.sample(withReplacement=False,
fraction=sample_fraction,
seed=10)
centroids = [sample_data.first()[1]
] # add first centroid to the collection of centroids
for _ in range(num_clusters - 1): # find the next k-1 centroids
distances = sample_data.\
mapValues(lambda values: minimum_distance_to_centroids(values, centroids)).persist()
furthest_point = sample_data.lookup(
distances.max(lambda pair: pair[1])[0])[0]
centroids.append(
furthest_point) # furthest from already selected points
centroids = [(min_cluster_id + i, centroid)
for i, centroid in enumerate(centroids)] # assign index
centroids = dict(centroids)
# ** perform clustering
num_iterations = 0
previous_cluster_sizes = dict()
while num_iterations < max_iterations:
print("current iteration:", num_iterations)
print("assign points to clusters")
cluster_result: RDD = data.mapValues(lambda values: (
assign_point_to_cluster(values, centroids), values)).persist()
cluster_sizes = cluster_result.map(
lambda pair: (pair[1][0], 1)).reduceByKey(lambda x, y: x + y)
cluster_sizes = dict(cluster_sizes.collect())
if num_iterations > 0: # after first iteration
num_reassigments = [
(cluster_sizes[cid] - previous_cluster_sizes[cid])
for cid in cluster_sizes.keys()
]
print("num_reassigments:", num_reassigments)
if max(num_reassigments) - min(
num_reassigments) < 3: # Now the process converges
break
previous_cluster_sizes = cluster_sizes.copy()
print("update centroids_:")
new_centroids = cluster_result. \
values(). \
flatMapValues(lambda features: [(i, feature) for i, feature in enumerate(features)]). \
map(lambda pair: ((pair[0], pair[1][0]), (pair[1][1], 1))). \
reduceByKey(lambda x, y: (x[0] + y[0], x[1] + y[1])). \
mapValues(lambda values: values[0] / values[1]). \
map(lambda pair: (pair[0][0], (pair[0][1], pair[1]))). \
groupByKey(). \
mapValues(sorted). \
mapValues(lambda values: [value for feature_index, value in values]). \
persist()
new_centroids = dict(new_centroids.collect())
centroids = new_centroids.copy()
num_iterations += 1
print("Converged. Total iterations:", num_iterations)
print(
"cluster size",
cluster_result.values().mapValues(
lambda values: 1).groupByKey().mapValues(len).collect())
return cluster_result
def test_pca(spark_context: SparkContext, mat: RowMatrix, rows: rdd.RDD):
pc: RowMatrix = pca(spark_context, mat, rows.count())
assert pc is not None
