[Spark][Python]DataFrame的左右连接例子
$ hdfs dfs -cat people.json
{"name":"Alice","pcode":"94304"}
{"name":"Brayden","age":30,"pcode":"94304"}
{"name":"Carla","age":19,"pcoe":"10036"}
{"name":"Diana","age":46}
{"name":"Etienne","pcode":"94104"}
$ hdfs dfs -cat pcodes.json
{"pcode":"10036","city":"New York","state":"NY"}
{"pcode":"87501","city":"Santa Fe","state":"NM"}
{"pcode":"94304","city":"Palo Alto","state":"CA"}
{"pcode":"94104","city":"San Francisco","state":"CA"}
$pyspark
sqlContext = HiveContext(sc)
peopleDF = sqlContext.read.json("people.json")
peopleDF.limit(5).show()
+----+-------+-----+-----+
| age| name|pcode| pcoe|
+----+-------+-----+-----+
|null| Alice|94304| null|
| 30|Brayden|94304| null|
| 19| Carla| null|10036|
| 46| Diana| null| null|
|null|Etienne|94104| null|
+----+-------+-----+-----+
sqlContext = HiveContext(sc)
pcodesDF = sqlContext.read.json("pcodes.json")
pcodesDF.limit(5).show()
+-------------+-----+-----+
| city|pcode|state|
+-------------+-----+-----+
| New York|10036| NY|
| Santa Fe|87501| NM|
| Palo Alto|94304| CA|
|San Francisco|94104| CA|
+-------------+-----+-----+
mydf000 = peopleDF.join(pcodesDF,"pcode")
mydf000.limit(5).show()
+-----+----+-------+----+-------------+-----+
|pcode| age| name|pcoe| city|state|
+-----+----+-------+----+-------------+-----+
|94304|null| Alice|null| Palo Alto| CA|
|94304| 30|Brayden|null| Palo Alto| CA|
|94104|null|Etienne|null|San Francisco| CA|
+-----+----+-------+----+-------------+-----+
mydf001=peopleDF.join(pcodesDF,"pcode","leftsemi")
mydf001.limit(5).show()
+-----+----+-------+----+
|pcode| age| name|pcoe|
+-----+----+-------+----+
|94304|null| Alice|null|
|94304| 30|Brayden|null|
|94104|null|Etienne|null|
+-----+----+-------+----+
mydf002=peopleDF.join(pcodesDF,"pcode","left_outer")
mydf002.limit(5).show()
+-----+----+-------+-----+-------------+-----+
|pcode| age| name| pcoe| city|state|
+-----+----+-------+-----+-------------+-----+
|94304|null| Alice| null| Palo Alto| CA|
|94304| 30|Brayden| null| Palo Alto| CA|
| null| 19| Carla|10036| null| null|
| null| 46| Diana| null| null| null|
|94104|null|Etienne| null|San Francisco| CA|
+-----+----+-------+-----+-------------+-----+
mydf003=peopleDF.join(pcodesDF,"pcode","right_outer")
mydf003.limit(5).show()
+-----+----+-------+----+-------------+-----+
|pcode| age| name|pcoe| city|state|
+-----+----+-------+----+-------------+-----+
|10036|null| null|null| New York| NY|
|87501|null| null|null| Santa Fe| NM|
|94304|null| Alice|null| Palo Alto| CA|
|94304| 30|Brayden|null| Palo Alto| CA|
|94104|null|Etienne|null|San Francisco| CA|
+-----+----+-------+----+-------------+-----+
