导入库
from pyspark import SparkConf, SparkContext
sc =SparkContext.getOrCreate()
创建RDD
data = sc.parallelize([('Amber', 22),
('Alfred', 23),
('Skye',4),
('Albert', 12),
('Amber', 9)])
data
--->ParallelCollectionRDD[0] at parallelize at PythonRDD.scala:175
.collect()函数：执行把全部数据集送回驱动的操作
data_heterogenous = sc.parallelize([('Ferrari', 'fast'),
{'Porsche': 100000},
['Spain', 'visited', 4504]
]).collect() #.collect()执行把该数据集送回驱动的操作
data_heterogenous
--->[('Ferrari', 'fast'), {'Porsche': 100000}, ['Spain', 'visited', 4504]]
索引其中某一个数值
data_heterogenous[1]['Porsche']
--->100000
读入压缩包文件
data_from_file = sc.textFile(r'D:\小鸡理财\OneDrive\python\book\PySpark实战指南\VS14MORT.txt.gz',4) #4代表被划分为4个分区
data_from_file
--->D:\小鸡理财\OneDrive\python\book\PySpark实战指南\VS14MORT.txt.gz MapPartitionsRDD[3] at textFile at NativeMethodAccessorImpl.java:0
.take()：读取指定行数
data_from_file.take(1)
--->
[' 1 2101 M1087 432311 4M4 2014U7CN I64 238 070 24 0111I64 01 I64 01 11 100 601']
示例函数
def extractInformation(row):
import re
import numpy as np
selected_indices = [
2,4,5,6,7,9,10,11,12,13,14,15,16,17,18,
19,21,22,23,24,25,27,28,29,30,32,33,34,
36,37,38,39,40,41,42,43,44,45,46,47,48,
49,50,51,52,53,54,55,56,58,60,61,62,63,
64,65,66,67,68,69,70,71,72,73,74,75,76,
77,78,79,81,82,83,84,85,87,89
]
record_split = re.compile(
r'([\s]{19})([0-9]{1})([\s]{40})([0-9\s]{2})([0-9\s]{1})([0-9]{1})([0-9]{2})' +
r'([\s]{2})([FM]{1})([0-9]{1})([0-9]{3})([0-9\s]{1})([0-9]{2})([0-9]{2})' +
r'([0-9]{2})([0-9\s]{2})([0-9]{1})([SMWDU]{1})([0-9]{1})([\s]{16})([0-9]{4})' +
r'([YNU]{1})([0-9\s]{1})([BCOU]{1})([YNU]{1})([\s]{34})([0-9\s]{1})([0-9\s]{1})' +
r'([A-Z0-9\s]{4})([0-9]{3})([\s]{1})([0-9\s]{3})([0-9\s]{3})([0-9\s]{2})([\s]{1})' +
r'([0-9\s]{2})([A-Z0-9\s]{7})([A-Z0-9\s]{7})([A-Z0-9\s]{7})([A-Z0-9\s]{7})' +
r'([A-Z0-9\s]{7})([A-Z0-9\s]{7})([A-Z0-9\s]{7})([A-Z0-9\s]{7})([A-Z0-9\s]{7})' +
r'([A-Z0-9\s]{7})([A-Z0-9\s]{7})([A-Z0-9\s]{7})([A-Z0-9\s]{7})([A-Z0-9\s]{7})' +
r'([A-Z0-9\s]{7})([A-Z0-9\s]{7})([A-Z0-9\s]{7})([A-Z0-9\s]{7})([A-Z0-9\s]{7})' +
r'([A-Z0-9\s]{7})([\s]{36})([A-Z0-9\s]{2})([\s]{1})([A-Z0-9\s]{5})([A-Z0-9\s]{5})' +
r'([A-Z0-9\s]{5})([A-Z0-9\s]{5})([A-Z0-9\s]{5})([A-Z0-9\s]{5})([A-Z0-9\s]{5})' +
r'([A-Z0-9\s]{5})([A-Z0-9\s]{5})([A-Z0-9\s]{5})([A-Z0-9\s]{5})([A-Z0-9\s]{5})' +
r'([A-Z0-9\s]{5})([A-Z0-9\s]{5})([A-Z0-9\s]{5})([A-Z0-9\s]{5})([A-Z0-9\s]{5})' +
r'([A-Z0-9\s]{5})([A-Z0-9\s]{5})([A-Z0-9\s]{5})([\s]{1})([0-9\s]{2})([0-9\s]{1})' +
r'([0-9\s]{1})([0-9\s]{1})([0-9\s]{1})([\s]{33})([0-9\s]{3})([0-9\s]{1})([0-9\s]{1})')
try:
rs = np.array(record_split.split(row))[selected_indices]
except:
rs = np.array(['-99'] * len(selected_indices))
return rs
map()转换：对每一个元素进行转换
data_from_file_conv = data_from_file.map(extractInformation)
# data_from_file_conv.map(lambda row: row).take(1)
data_2014 = data_from_file_conv.map(lambda x:int(x[16]))
data_2014.take(15)
--->
[2014,
2014,
2014,
2014,
2014,
2014,
2014,
2014,
2014,
-99,
2014,
2014,
-99,
2014,
2014]
data_2014_2 = data_from_file_conv.map(lambda row: (row[16], int(row[16])))
data_2014_2.take(10)
--->
[('2014', 2014),
('2014', 2014),
('2014', 2014),
('2014', 2014),
('2014', 2014),
('2014', 2014),
('2014', 2014),
('2014', 2014),
('2014', 2014),
('-99', -99)]
.filter()转换：从数据集中选择符合条件的数据
data_filtered = data_from_file_conv.filter(lambda row: row[16] == '2014' and row[21] == '0')
data_filtered.take(1)
--->
[array(['2', '12', ' ', '0', '07', 'F', '1', '030', ' ', '32', '12', '05',
' ', '1', 'D', '6', '2014', 'N', '1', 'U', 'Y', '0', '9', 'X44 ',
'420', '122', ' ', '39', '05', '11T391 ', '12X44 ', '13T401 ',
'14T424 ', '61F199 ', ' ', ' ', ' ', ' ',
' ', ' ', ' ', ' ', ' ', ' ',
' ', ' ', ' ', ' ', ' ', '05',
'X44 ', 'F199 ', 'T391 ', 'T401 ', 'T424 ', ' ', ' ',
' ', ' ', ' ', ' ', ' ', ' ', ' ',
' ', ' ', ' ', ' ', ' ', ' ', '01', ' ',
' ', '1', '1', '100', '6'],
dtype='<U40')]
.count() ：统计个数
data_filtered.count()
--->22
.flatMap() : 返回扁平的结果，与.fliter()类似
data_2014_flat = data_from_file_conv.flatMap(lambda row: (row[16], int(row[16]) + 1))
data_2014_flat.take(10)
--->['2014', 2015, '2014', 2015, '2014', 2015, '2014', 2015, '2014', 2015]
.distinct()：返回唯一值个数
distinct_gender = data_from_file_conv.map(lambda row:row[5]).distinct()
distinct_gender.collect()
--->['M', 'F', '-99']
.sample()：返回随机样本集
fraction = 0.1
data_sample = data_from_file_conv.sample(False, fraction, 666)
#第一参数指定采用是否替换，第二参数指定样本占全体的比例，第三参数是伪随机数的种子
data_sample.take(1)
--->
[array(['1', ' ', '5', '1', '01', 'F', '1', '082', ' ', '42', '22', '10',
' ', '4', 'W', '5', '2014', 'U', '7', 'C', 'N', ' ', ' ', 'I251',
'215', '063', ' ', '21', '02', '11I350 ', '21I251 ', ' ',
' ', ' ', ' ', ' ', ' ', ' ',
' ', ' ', ' ', ' ', ' ', ' ',
' ', ' ', ' ', ' ', ' ', '02',
'I251 ', 'I350 ', ' ', ' ', ' ', ' ', ' ',
' ', ' ', ' ', ' ', ' ', ' ', ' ',
' ', ' ', ' ', ' ', ' ', ' ', '28', ' ',
' ', '2', '4', '100', '8'],
dtype='<U40')]
.leftOuterJoin()：左连接
rdd1 = sc.parallelize([('a', 1), ('b', 4), ('c',10)])
rdd2 = sc.parallelize([('a', 4), ('a', 1), ('b', '6'), ('d', 15)])
rdd3 = rdd1.leftOuterJoin(rdd2)
rdd3.collect()
--->[('b', (4, '6')), ('c', (10, None)), ('a', (1, 4)), ('a', (1, 1))]
.join()：内连接
rdd4 = rdd1.join(rdd2)
rdd4.collect()
--->[('b', (4, '6')), ('a', (1, 4)), ('a', (1, 1))]
----------------------------------------------------分割线----------------------------------------------------
查找重复值并删除
导入库
from pyspark.sql import SQLContext
spark = SQLContext(sc)
创建DataFrame
df = spark.createDataFrame([
(1, 144.5, 5.9, 33, 'M'),
(2, 167.2, 5.4, 45, 'M'),
(3, 124.1, 5.2, 23, 'F'),
(4, 144.5, 5.9, 33, 'M'),
(5, 133.2, 5.7, 54, 'F'),
(3, 124.1, 5.2, 23, 'F'),
(5, 129.2, 5.3, 42, 'M'),
], ['id', 'weight', 'height', 'age', 'gender'])
.show()：打印
df.show()
--->
+---+------+------+---+------+
| id|weight|height|age|gender|
+---+------+------+---+------+
| 1| 144.5| 5.9| 33| M|
| 2| 167.2| 5.4| 45| M|
| 3| 124.1| 5.2| 23| F|
| 4| 144.5| 5.9| 33| M|
| 5| 133.2| 5.7| 54| F|
| 3| 124.1| 5.2| 23| F|
| 5| 129.2| 5.3| 42| M|
+---+------+------+---+------+
df.count()
--->7
df.distinct().count() #有两行整行数据都是一样的
--->6
.drop_duplicates()：删除重复行
df = df.drop_duplicates()
df.show()
--->
+---+------+------+---+------+
| id|weight|height|age|gender|
+---+------+------+---+------+
| 5| 133.2| 5.7| 54| F|
| 5| 129.2| 5.3| 42| M|
| 1| 144.5| 5.9| 33| M|
| 4| 144.5| 5.9| 33| M|
| 2| 167.2| 5.4| 45| M|
| 3| 124.1| 5.2| 23| F|
+---+------+------+---+------+
df.distinct().count()
--->6
.select()：选择特定条件的列
df.select([
c for c in df.columns if c != 'id'
]).distinct().count()
--->5
df.select(['id']).distinct().count()
--->5
#只查找指定的列
df = df.drop_duplicates(subset = [
c for c in df.columns if c != 'id'
])
df.show()
--->
+---+------+------+---+------+
| id|weight|height|age|gender|
+---+------+------+---+------+
| 5| 133.2| 5.7| 54| F|
| 1| 144.5| 5.9| 33| M|
| 2| 167.2| 5.4| 45| M|
| 3| 124.1| 5.2| 23| F|
| 5| 129.2| 5.3| 42| M|
+---+------+------+---+------+
.agg()
import pyspark.sql.functions as fn
df.agg(fn.count('id').alias('count'),
fn.countDistinct('id').alias('distinct')).show()
--->
+-----+--------+
|count|distinct|
+-----+--------+
| 5| 4|
+-----+--------+
.monotonically_increasing_id()：给每条记录提供唯一且递增的ID
df.withColumn('new_id',fn.monotonically_increasing_id()).show()
--->
+---+------+------+---+------+-------------+
| id|weight|height|age|gender| new_id|
+---+------+------+---+------+-------------+
| 5| 133.2| 5.7| 54| F| 25769803776|
| 1| 144.5| 5.9| 33| M| 171798691840|
| 2| 167.2| 5.4| 45| M| 592705486848|
| 3| 124.1| 5.2| 23| F|1236950581248|
| 5| 129.2| 5.3| 42| M|1365799600128|
+---+------+------+---+------+-------------+
----------------------------------------------------分割线----------------------------------------------------
缺失值处理
导入库
from pyspark import SparkConf, SparkContext
sc =SparkContext.getOrCreate()
from pyspark.sql import SQLContext
spark = SQLContext(sc)
示例数据
df_miss = spark.createDataFrame([
(1, 143.5, 5.6, 28, 'M', 100000),
(2, 167.2, 5.4, 45, 'M', None),
(3, None , 5.2, None, None, None),
(4, 144.5, 5.9, 33, 'M', None),
(5, 133.2, 5.7, 54, 'F', None),
(6, 124.1, 5.2, None, 'F', None),
(7, 129.2, 5.3, 42, 'M', 76000),
], ['id', 'weight', 'height', 'age', 'gender', 'income'])
df_miss.show()
--->
+---+------+------+----+------+------+
| id|weight|height| age|gender|income|
+---+------+------+----+------+------+
| 1| 143.5| 5.6| 28| M|100000|
| 2| 167.2| 5.4| 45| M| null|
| 3| null| 5.2|null| null| null|
| 4| 144.5| 5.9| 33| M| null|
| 5| 133.2| 5.7| 54| F| null|
| 6| 124.1| 5.2|null| F| null|
| 7| 129.2| 5.3| 42| M| 76000|
+---+------+------+----+------+------+
计算每行的空值个数
df_miss.rdd.map(lambda row:(row['id'],sum([c == None for c in row]))).collect()
--->[(1, 0), (2, 1), (3, 4), (4, 1), (5, 1), (6, 2), (7, 0)]
从前面的结果中查看第3行的值
df_miss.where('id == 3').show()
--->
+---+------+------+----+------+------+
| id|weight|height| age|gender|income|
+---+------+------+----+------+------+
| 3| null| 5.2|null| null| null|
+---+------+------+----+------+------+
计算每列的空值比例
import pyspark.sql.functions as fn
df_miss.agg(*[
(1 - (fn.count(c) / fn.count('*'))).alias(c + '_missing')
for c in df_miss.columns
]).show()
--->
+----------+------------------+--------------+------------------+------------------+------------------+
|id_missing| weight_missing|height_missing| age_missing| gender_missing| income_missing|
+----------+------------------+--------------+------------------+------------------+------------------+
| 0.0|0.1428571428571429| 0.0|0.2857142857142857|0.1428571428571429|0.7142857142857143|
+----------+------------------+--------------+------------------+------------------+------------------+
去除'income'列
df_miss_no_income = df_miss.select([c for c in df_miss.columns if c != 'income'])
df_miss_no_income.show()
--->
+---+------+------+----+------+
| id|weight|height| age|gender|
+---+------+------+----+------+
| 1| 143.5| 5.6| 28| M|
| 2| 167.2| 5.4| 45| M|
| 3| null| 5.2|null| null|
| 4| 144.5| 5.9| 33| M|
| 5| 133.2| 5.7| 54| F|
| 6| 124.1| 5.2|null| F|
| 7| 129.2| 5.3| 42| M|
+---+------+------+----+------+
去除空值个数大于3个的行
df_miss_no_income.dropna(thresh=3).show()
--->
+---+------+------+----+------+
| id|weight|height| age|gender|
+---+------+------+----+------+
| 1| 143.5| 5.6| 28| M|
| 2| 167.2| 5.4| 45| M|
| 4| 144.5| 5.9| 33| M|
| 5| 133.2| 5.7| 54| F|
| 6| 124.1| 5.2|null| F|
| 7| 129.2| 5.3| 42| M|
+---+------+------+----+------+
用平均值填充空值（除字符串列）
#计算数值列的平均值并转化为字典
means = df_miss_no_income.agg(
*[fn.mean(c).alias(c) for c in df_miss_no_income.columns if c != 'gender']
).toPandas().to_dict('records')[0]
#补充字符串列的替代值到字典
means['gender'] = 'missing'
#打印字典
print('means:',means)
--->means: {'id': 4.0, 'weight': 140.28333333333333, 'height': 5.4714285714285706, 'age': 40.399999999999999, 'gender': 'missing'}
#填充空值
df_miss_no_income.fillna(means).show()
--->
+---+------------------+------+---+-------+
| id| weight|height|age| gender|
+---+------------------+------+---+-------+
| 1| 143.5| 5.6| 28| M|
| 2| 167.2| 5.4| 45| M|
| 3|140.28333333333333| 5.2| 40|missing|
| 4| 144.5| 5.9| 33| M|
| 5| 133.2| 5.7| 54| F|
| 6| 124.1| 5.2| 40| F|
| 7| 129.2| 5.3| 42| M|
+---+------------------+------+---+-------+
----------------------------------------------------分割线----------------------------------------------------
离群值处理
示例数据
df_outliers = spark.createDataFrame([
(1, 143.5, 5.3, 28),
(2, 154.2, 5.5, 45),
(3, 342.3, 5.1, 99),
(4, 144.5, 5.5, 33),
(5, 133.2, 5.4, 54),
(6, 124.1, 5.1, 21),
(7, 129.2, 5.3, 42),
], ['id', 'weight', 'height', 'age'])
df_outliers.show()
--->
+---+------+------+---+
| id|weight|height|age|
+---+------+------+---+
| 1| 143.5| 5.3| 28|
| 2| 154.2| 5.5| 45|
| 3| 342.3| 5.1| 99|
| 4| 144.5| 5.5| 33|
| 5| 133.2| 5.4| 54|
| 6| 124.1| 5.1| 21|
| 7| 129.2| 5.3| 42|
+---+------+------+---+
计算数据列的离群边界值
cols = ['weight', 'height', 'age']
bounds = {}
for col in cols:
quantiles = df_outliers.approxQuantile(col, [0.25, 0.75], 0.05)
IQR = quantiles[1] - quantiles[0]
bounds[col] = [quantiles[0] - 1.5 * IQR, quantiles[1] + 1.5 * IQR]
print('bounds:',bounds)
--->bounds: {'weight': [91.69999999999999, 191.7], 'height': [4.499999999999999, 6.1000000000000005], 'age': [-11.0, 93.0]}
计算示例数据与其边界值的关系
outliers = df_outliers.select(*['id'] + [
(
(df_outliers[c] < bounds[c][0]) |
(df_outliers[c] > bounds[c][1])
).alias(c + '_o') for c in cols
])
outliers.show()
--->
+---+--------+--------+-----+
| id|weight_o|height_o|age_o|
+---+--------+--------+-----+
| 1| false| false|false|
| 2| false| false|false|
| 3| true| false| true|
| 4| false| false|false|
| 5| false| false|false|
| 6| false| false|false|
| 7| false| false|false|
+---+--------+--------+-----+
离群值提取
#将示例数据和边界值判断数据合并
df_outliers = df_outliers.join(outliers, on='id')
#提取'weight'列的离群值
df_outliers.filter('weight_o').select('id', 'weight').show()
--->
#提取'age'列的离群值
# df_outliers.filter('age_o').select('id', 'age').show()
----------------------------------------------------分割线----------------------------------------------------
查看描述性数据
import pyspark.sql.types as typ
从csv导入数据
fraud = sc.textFile(r'D:\小鸡理财\OneDrive\python\Jupyter\spark\ccFraud.csv')
header = fraud.first()
fraud = fraud.filter(lambda row: row != header).map(lambda row: [int(elem) for elem in row.split(',')])
fraud.take(1)
--->[[1, 1, 35, 1, 3000, 4, 14, 2, 0]]
创建数据帧
fields = [
*[
typ.StructField(h[1:-1], typ.IntegerType(), True)
for h in header.split(',')
]
]
print('fields:',fields)
--->fields: [StructField(custID,IntegerType,true), StructField(gender,IntegerType,true), StructField(state,IntegerType,true), StructField(cardholder,IntegerType,true), StructField(balance,IntegerType,true), StructField(numTrans,IntegerType,true), StructField(numIntlTrans,IntegerType,true), StructField(creditLine,IntegerType,true), StructField(fraudRisk,IntegerType,true)]
schema = typ.StructType(fields)
print('schema:',schema)
--->schema: StructType(List(StructField(custID,IntegerType,true),StructField(gender,IntegerType,true),StructField(state,IntegerType,true),StructField(cardholder,IntegerType,true),StructField(balance,IntegerType,true),StructField(numTrans,IntegerType,true),StructField(numIntlTrans,IntegerType,true),StructField(creditLine,IntegerType,true),StructField(fraudRisk,IntegerType,true)))
fraud_df = spark.createDataFrame(fraud, schema)
fraud_df.printSchema()
--->
root
|-- custID: integer (nullable = true)
|-- gender: integer (nullable = true)
|-- state: integer (nullable = true)
|-- cardholder: integer (nullable = true)
|-- balance: integer (nullable = true)
|-- numTrans: integer (nullable = true)
|-- numIntlTrans: integer (nullable = true)
|-- creditLine: integer (nullable = true)
|-- fraudRisk: integer (nullable = true)
fraud_df.show()
--->
+------+------+-----+----------+-------+--------+------------+----------+---------+
|custID|gender|state|cardholder|balance|numTrans|numIntlTrans|creditLine|fraudRisk|
+------+------+-----+----------+-------+--------+------------+----------+---------+
| 1| 1| 35| 1| 3000| 4| 14| 2| 0|
| 2| 2| 2| 1| 0| 9| 0| 18| 0|
| 3| 2| 2| 1| 0| 27| 9| 16| 0|
| 4| 1| 15| 1| 0| 12| 0| 5| 0|
| 5| 1| 46| 1| 0| 11| 16| 7| 0|
| 6| 2| 44| 2| 5546| 21| 0| 13| 0|
| 7| 1| 3| 1| 2000| 41| 0| 1| 0|
| 8| 1| 10| 1| 6016| 20| 3| 6| 0|
| 9| 2| 32| 1| 2428| 4| 10| 22| 0|
| 10| 1| 23| 1| 0| 18| 56| 5| 0|
| 11| 1| 46| 1| 4601| 54| 0| 4| 0|
| 12| 1| 10| 1| 3000| 20| 0| 2| 0|
| 13| 1| 6| 1| 0| 45| 2| 4| 0|
| 14| 2| 38| 1| 9000| 41| 3| 8| 0|
| 15| 1| 27| 1| 5227| 60| 0| 17| 0|
| 16| 1| 44| 1| 0| 22| 0| 5| 0|
| 17| 2| 18| 1| 13970| 20| 0| 13| 0|
| 18| 1| 35| 1| 3113| 13| 6| 8| 0|
| 19| 1| 5| 1| 9000| 20| 2| 8| 0|
| 20| 2| 31| 1| 1860| 21| 10| 8| 0|
+------+------+-----+----------+-------+--------+------------+----------+---------+
only showing top 20 rows
查看性别的个数
fraud_df.groupby('gender').count().show()
--->
+------+-------+
|gender| count|
+------+-------+
| 1|6178231|
| 2|3821769|
+------+-------+
查看每列的描述性统计
numerical = ['balance', 'numTrans', 'numIntlTrans']
desc = fraud_df.describe(numerical)
desc.show()
--->
+-------+-----------------+------------------+-----------------+
|summary| balance| numTrans| numIntlTrans|
+-------+-----------------+------------------+-----------------+
| count| 10000000| 10000000| 10000000|
| mean| 4109.9199193| 28.9351871| 4.0471899|
| stddev|3996.847309737258|26.553781024523122|8.602970115863904|
| min| 0| 0| 0|
| max| 41485| 100| 60|
+-------+-----------------+------------------+-----------------+
----------------------------------------------------分割线----------------------------------------------------
可视化
%matplotlib inline
import matplotlib.pyplot as plt
plt.style.use('ggplot')
fraud_df.select('balance').show()
--->
+-------+
|balance|
+-------+
| 3000|
| 0|
| 0|
| 0|
| 0|
| 5546|
| 2000|
| 6016|
| 2428|
| 0|
| 4601|
| 3000|
| 0|
| 9000|
| 5227|
| 0|
| 13970|
| 3113|
| 9000|
| 1860|
+-------+
only showing top 20 rows
绘制直方图
hists = fraud_df.select('balance').rdd.flatMap(lambda row: row).histogram(20)
data = {
'bins': hists[0][:-1],
'freq': hists[1]
}
fig = plt.figure(figsize=(12,9))
ax = fig.add_subplot(1, 1, 1)
ax.bar(data['bins'], data['freq'], width=2000)
ax.set_title('Histogram of \'balance\'')
plt.savefig('B05793_05_22.png', dpi=300)
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