Aggregate one column, but show all columns in select - apache-spark

I try to show maximum value from column while I group rows by date column.
So i tried this code
maxVal = dfSelect.select('*')\
.groupBy('DATE')\
.agg(max('CLOSE'))
But output looks like that:
+----------+----------+
| DATE|max(CLOSE)|
+----------+----------+
|1987-05-08| 43.51|
|1987-05-29| 39.061|
+----------+----------+
I wanna have output like below
+------+---+----------+------+------+------+------+------+---+----------+
|TICKER|PER| DATE| TIME| OPEN| HIGH| LOW| CLOSE|VOL|max(CLOSE)|
+------+---+----------+------+------+------+------+------+---+----------+
| CDG| D|1987-01-02|000000|50.666|51.441|49.896|50.666| 0| 50.666|
| ABC| D|1987-01-05|000000|51.441| 52.02|51.441|51.441| 0| 51.441|
+------+---+----------+------+------+------+------+------+---+----------+
So my question is how to change the code to have output with all columns and aggregated 'CLOSE' column?
Scheme of my data looks like below:
root
|-- TICKER: string (nullable = true)
|-- PER: string (nullable = true)
|-- DATE: date (nullable = true)
|-- TIME: string (nullable = true)
|-- OPEN: float (nullable = true)
|-- HIGH: float (nullable = true)
|-- LOW: float (nullable = true)
|-- CLOSE: float (nullable = true)
|-- VOL: integer (nullable = true)
|-- OPENINT: string (nullable = true)

If you want the same aggregation all your columns in the original dataframe, then you can do something like,
import pyspark.sql.functions as F
expr = [F.max(coln).alias(coln) for coln in df.columns if 'date' not in coln] # df is your datafram
df_res = df.groupby('date').agg(*expr)
If you want multiple aggregations, then you can do like,
sub_col1 = # define
sub_col2=# define
expr1 = [F.max(coln).alias(coln) for coln in sub_col1 if 'date' not in coln]
expr2 = [F.first(coln).alias(coln) for coln in sub_col2 if 'date' not in coln]
expr=expr1+expr2
df_res = df.groupby('date').agg(*expr)
If you want only one of the columns aggregated and added to your original dataframe, then you can do a selfjoin after aggregating
df_agg = df.groupby('date').agg(F.max('close').alias('close_agg')).withColumn("dummy",F.lit("dummmy")) # dummy column is needed as a workaround in spark issues of self join
df_join = df.join(df_agg,on='date',how='left')
or you can use a windowing function
from pyspark.sql import Window
w= Window.partitionBy('date')
df_res = df.withColumn("max_close",F.max('close').over(w))

Related

How to convert a list with structure like (key1, list(key2, value)) into a dataframe in pyspark?

I have a list as shown below:
It is of the type as shown below:
[(key1, [(key11, value11), (key12, value12)]), (key2, [(key21, value21), (key22, value22)...])...]
A sample structure is shown below:
[('1052762305',
[('1007819788', 0.9206884810054885),
('1005886801', 0.913818268123084),
('1003863766', 0.9131746152849486),
('1007811435', 0.9128666156173751),
('1005879599', 0.9126368405937075),
('1003705572', 0.9122051062936369),
('1007804896', 0.9083424459788203),
('1005890270', 0.8982097535650703),
('1007806781', 0.8708761186829758),
('1003670458', 0.8452789033694487)]),
('1064808607',
[('1007804896', 0.9984397647563017),
('1003705572', 0.9970498347406341),
('1005879599', 0.9951581013190172),
('1007811435', 0.9934813787902085),
('1005886801', 0.9930572794622374),
('1003863766', 0.9928815742735568),
('1007819788', 0.9869723713790797),
('1005890270', 0.9642640856016443),
('1007806781', 0.9211558765137313),
('1003670458', 0.8519872445941068)])]
I want to convert this into a dataframe of the form
key1 key2 score
1052762305 1007819788 0.9206884810054885
1052762305 1005886801 0.913818268123084
1052762305 1003863766 0.9131746152849486
... ... ...
1064808607 1007804896 0.9984397647563017
1064808607 1003705572 0.9970498347406341
1064808607 1005879599 0.9951581013190172
... ... ...
How can we implement this in pyspark?
You can create a schema upfront with the input. Use explode and access the elements with in the value struct.
from pyspark.sql import SparkSession
from pyspark.sql import functions as F
from pyspark.sql.types import StructType, StructField,StringType,ArrayType, DoubleType
spark = SparkSession.builder \
.appName('SO')\
.getOrCreate()
schema = StructType([StructField("key1",StringType()), StructField("value",ArrayType(
StructType([ StructField("key2", StringType()),
StructField("score", DoubleType())])
)) ])
df = spark.createDataFrame(
[('1052762305',
[('1007819788', 0.9206884810054885),
('1005886801', 0.913818268123084),
('1003863766', 0.9131746152849486),
('1007811435', 0.9128666156173751),
('1005879599', 0.9126368405937075),
('1003705572', 0.9122051062936369),
('1007804896', 0.9083424459788203),
('1005890270', 0.8982097535650703),
('1007806781', 0.8708761186829758),
('1003670458', 0.8452789033694487)]),
('1064808607',
[('1007804896', 0.9984397647563017),
('1003705572', 0.9970498347406341),
('1005879599', 0.9951581013190172),
('1007811435', 0.9934813787902085),
('1005886801', 0.9930572794622374),
('1003863766', 0.9928815742735568),
('1007819788', 0.9869723713790797),
('1005890270', 0.9642640856016443),
('1007806781', 0.9211558765137313),
('1003670458', 0.8519872445941068)])
],schema
)
df.show()
+----------+--------------------+
| key1| value |
+----------+--------------------+
|1052762305|[[1007819788, 0.9...|
|1064808607|[[1007804896, 0.9...|
+----------+--------------------+
df.printSchema()
root
|-- key1: string (nullable = true)
|-- value: array (nullable = true)
| |-- element: struct (containsNull = true)
| | |-- key2: string (nullable = true)
| | |-- score: double (nullable = true)
df1=df.select('key1',F.explode('value').alias('value'))
df1.show()
+----------+--------------------+
| key1| value |
+----------+--------------------+
|1052762305|[1007819788, 0.92...|
|1052762305|[1005886801, 0.91...|
|1052762305|[1003863766, 0.91...|
|1052762305|[1007811435, 0.91...|
|1052762305|[1005879599, 0.91...|
|1052762305|[1003705572, 0.91...|
|1052762305|[1007804896, 0.90...|
|1052762305|[1005890270, 0.89...|
|1052762305|[1007806781, 0.87...|
|1052762305|[1003670458, 0.84...|
|1064808607|[1007804896, 0.99...|
|1064808607|[1003705572, 0.99...|
|1064808607|[1005879599, 0.99...|
|1064808607|[1007811435, 0.99...|
|1064808607|[1005886801, 0.99...|
|1064808607|[1003863766, 0.99...|
|1064808607|[1007819788, 0.98...|
|1064808607|[1005890270, 0.96...|
|1064808607|[1007806781, 0.92...|
|1064808607|[1003670458, 0.85...|
+----------+--------------------+
df1.printSchema()
root
|-- key1: string (nullable = true)
|-- value: struct (nullable = true)
| |-- key2: string (nullable = true)
| |-- score: double (nullable = true)
df1.select("key1", "value.key2","value.score").show()
+----------+----------+------------------+
| key1| key2| score|
+----------+----------+------------------+
|1052762305|1007819788|0.9206884810054885|
|1052762305|1005886801| 0.913818268123084|
|1052762305|1003863766|0.9131746152849486|
|1052762305|1007811435|0.9128666156173751|
|1052762305|1005879599|0.9126368405937075|
|1052762305|1003705572|0.9122051062936369|
|1052762305|1007804896|0.9083424459788203|
|1052762305|1005890270|0.8982097535650703|
|1052762305|1007806781|0.8708761186829758|
|1052762305|1003670458|0.8452789033694487|
|1064808607|1007804896|0.9984397647563017|
|1064808607|1003705572|0.9970498347406341|
|1064808607|1005879599|0.9951581013190172|
|1064808607|1007811435|0.9934813787902085|
|1064808607|1005886801|0.9930572794622374|
|1064808607|1003863766|0.9928815742735568|
|1064808607|1007819788|0.9869723713790797|
|1064808607|1005890270|0.9642640856016443|
|1064808607|1007806781|0.9211558765137313|
|1064808607|1003670458|0.8519872445941068|
You basically need to do following:
create a dataframe from your list
promote the pairs from elements of array into a separate row by using explode
extract key & value from pair via select
This could be done by something like this (source data is in the variable called a):
from pyspark.sql.functions import explode, col
df = spark.createDataFrame(a, ['key1', 'val'])
df2 = df.select(col('key1'), explode(col('val')).alias('val'))
df3 = df2.select('key1', col('val')._1.alias('key2'), col('val')._2.alias('value'))
we can check that schema & data is matching:
>>> df3.printSchema()
root
|-- key1: string (nullable = true)
|-- key2: string (nullable = true)
|-- value: double (nullable = true)
>>> df3.show(2)
+----------+----------+------------------+
| key1| key2| value|
+----------+----------+------------------+
|1052762305|1007819788|0.9206884810054885|
|1052762305|1005886801| 0.913818268123084|
+----------+----------+------------------+
only showing top 2 rows
we can also check the schema for intermediate results:
>>> df.printSchema()
root
|-- key1: string (nullable = true)
|-- val: array (nullable = true)
| |-- element: struct (containsNull = true)
| | |-- _1: string (nullable = true)
| | |-- _2: double (nullable = true)
>>> df2.printSchema()
root
|-- key1: string (nullable = true)
|-- val: struct (nullable = true)
| |-- _1: string (nullable = true)
| |-- _2: double (nullable = true)

How to remove array element in PySpark dataframe?

I want to remove barcode from this array.
My dataframe looks like the sample given below,
|-- variants: array (nullable = true)
| |-- element: struct (containsNull = true)
| | |-- admin_graphql_api_id: string (nullable = true)
| | |-- barcode: string (nullable = true)
| | |-- compare_at_price: string (nullable = true)
Can you help me to remove the element from the dataframe using PySpark.
You can use arrays_zip:
from pyspark.sql.types import ArrayType, StringType, StructType, StructField
df = df.withColumn("variants", F.arrays_zip("variants.admin_graphql_api_id", "variants.compare_at_price"))
df = df.withColumn("variants", F.col("variants").cast(schema))
df.printSchema()
prints
root
|-- variants: array (nullable = true)
| |-- element: struct (containsNull = true)
| | |-- admin_graphql_api_id: string (nullable = true)
| | |-- compare_at_price: string (nullable = true)
The second withColumn is necessary to set the field names of the new struct.
arrays_zip is only available for Spark version >= 2.4.0. If you are using an older Spark version, you could use an UDF:
def func(array):
return [[x.admin_graphql_api_id, x.compare_at_price] for x in array]
func_udf = F.udf(func, schema)
df = df.withColumn("variants", func_udf("variants"))

How to JSON-escape a String field in Spark dataFrame with new column

How to write a new column with JSON format through DataFrame. I tried several approaches but it's writing the data as JSON-escaped String field.
Currently its writing as
{"test":{"id":1,"name":"name","problem_field": "{\"x\":100,\"y\":200}"}}
Instead I want it to be as
{"test":{"id":1,"name":"name","problem_field": {"x":100,"y":200}}}
problem_field is a new column that is being created based on the values read from other fields as:
val dataFrame = oldDF.withColumn("problem_field", s)
I have tried the following approaches
dataFrame.write.json(<<outputPath>>)
dataFrame.toJSON.map(value => value.replace("\\", "").replace("{\"value\":\"", "").replace("}\"}", "}")).write.json(<<outputPath>>)
Tried converting to DataSet as well but no luck. Any pointers are greatly appreciated.
I have already tried the logic mentioned here: How to let Spark parse a JSON-escaped String field as a JSON Object to infer the proper structure in DataFrames?
For starters, your example data has an extraneous comma after "y\":200 which will prevent it from being parsed as it is not valid JSON.
From there, you can use from_json to parse the field, assuming you know the schema. In this example, I'm parsing the field separately to first get the schema:
scala> val json = spark.read.json(Seq("""{"test":{"id":1,"name":"name","problem_field": "{\"x\":100,\"y\":200}"}}""").toDS)
json: org.apache.spark.sql.DataFrame = [test: struct<id: bigint, name: string ... 1 more field>]
scala> json.printSchema
root
|-- test: struct (nullable = true)
| |-- id: long (nullable = true)
| |-- name: string (nullable = true)
| |-- problem_field: string (nullable = true)
scala> val problem_field = spark.read.json(json.select($"test.problem_field").map{
case org.apache.spark.sql.Row(x : String) => x
})
problem_field: org.apache.spark.sql.DataFrame = [x: bigint, y: bigint]
scala> problem_field.printSchema
root
|-- x: long (nullable = true)
|-- y: long (nullable = true)
scala> val fixed = json.withColumn("test", struct($"test.id", $"test.name", from_json($"test.problem_field", problem_field.schema).as("problem_field")))
fixed: org.apache.spark.sql.DataFrame = [test: struct<id: bigint, name: string ... 1 more field>]
scala> fixed.printSchema
root
|-- test: struct (nullable = false)
| |-- id: long (nullable = true)
| |-- name: string (nullable = true)
| |-- problem_field: struct (nullable = true)
| | |-- x: long (nullable = true)
| | |-- y: long (nullable = true)
If the schema of problem_fields contents is inconsistent between rows, this solution will still work but may not be an optimal way of handling things, as it will produce a sparse Dataframe where each row contains every field encountered in problem_field. For example:
scala> val json = spark.read.json(Seq("""{"test":{"id":1,"name":"name","problem_field": "{\"x\":100,\"y\":200}"}}""", """{"test":{"id":1,"name":"name","problem_field": "{\"a\":10,\"b\":20}"}}""").toDS)
json: org.apache.spark.sql.DataFrame = [test: struct<id: bigint, name: string ... 1 more field>]
scala> val problem_field = spark.read.json(json.select($"test.problem_field").map{case org.apache.spark.sql.Row(x : String) => x})
problem_field: org.apache.spark.sql.DataFrame = [a: bigint, b: bigint ... 2 more fields]
scala> problem_field.printSchema
root
|-- a: long (nullable = true)
|-- b: long (nullable = true)
|-- x: long (nullable = true)
|-- y: long (nullable = true)
scala> val fixed = json.withColumn("test", struct($"test.id", $"test.name", from_json($"test.problem_field", problem_field.schema).as("problem_field")))
fixed: org.apache.spark.sql.DataFrame = [test: struct<id: bigint, name: string ... 1 more field>]
scala> fixed.printSchema
root
|-- test: struct (nullable = false)
| |-- id: long (nullable = true)
| |-- name: string (nullable = true)
| |-- problem_field: struct (nullable = true)
| | |-- a: long (nullable = true)
| | |-- b: long (nullable = true)
| | |-- x: long (nullable = true)
| | |-- y: long (nullable = true)
scala> fixed.select($"test.problem_field.*").show
+----+----+----+----+
| a| b| x| y|
+----+----+----+----+
|null|null| 100| 200|
| 10| 20|null|null|
+----+----+----+----+
Over the course of hundreds, thousands, or millions of rows, you can see how this would present a problem.

Slice array of structs using column values

I want to use Spark slice function with start and length defined as Column(s).
def slice(x: Column, start: Int, length: Int): Column
x looks like this:
`|-- x: array (nullable = true)
| |-- element: struct (containsNull = true)
| | |-- a: double (nullable = true)
| | |-- b : double (nullable = true)
| | |-- c: double (nullable = true)
| | |-- d: string (nullable = true)
| | |-- e: double (nullable = true)
| | |-- f: double (nullable = true)
| | |-- g: long (nullable = true)
| | |-- h: double (nullable = true)
| | |-- i: double (nullable = true)
...
`
any idea on how to achieve this ?
Thanks !
You cannot use the built-in DataFrame DSL function slice for this (as it needs constant slice bounds), you can use an UDF for that. If df is your dataframe and you have a from und until column, then you can do:
val mySlice = udf(
(data:Seq[Row], from:Int, until:Int) => data.slice(from,until),
df.schema.fields.find(_.name=="x").get.dataType
)
df
.select(mySlice($"x",$"from",$"until"))
.show()
Alternatively, you can use the SQL-Expression in Spark SQL:
df
.select(expr("slice(x,from,until)"))
.show()

Handle string to array conversion in pyspark dataframe

I have a file(csv) which when read in spark dataframe has the below values for print schema
-- list_values: string (nullable = true)
the values in the column list_values are something like:
[[[167, 109, 80, ...]]]
Is it possible to convert this to array type instead of string?
I tried splitting it and using code available online for similar problems:
df_1 = df.select('list_values', split(col("list_values"), ",\s*").alias("list_values"))
but if I run the above code the array which I get skips a lot of values in the original array i.e.
output of the above code is:
[, 109, 80, 69, 5...
which is different from original array i.e. (-- 167 is missing)
[[[167, 109, 80, ...]]]
Since I am new to spark I don't have much knowledge how it is done (For python I could have done ast.literal_eval but spark has no provision for this.
So I'll repeat the question again :
How can I convert/cast an array stored as string to array i.e.
'[]' to [] conversion
Suppose your DataFrame was the following:
df.show()
#+----+------------------+
#|col1| col2|
#+----+------------------+
#| a|[[[167, 109, 80]]]|
#+----+------------------+
df.printSchema()
#root
# |-- col1: string (nullable = true)
# |-- col2: string (nullable = true)
You could use pyspark.sql.functions.regexp_replace to remove the leading and trailing square brackets. Once that's done, you can split the resulting string on ", ":
from pyspark.sql.functions import split, regexp_replace
df2 = df.withColumn(
"col3",
split(regexp_replace("col2", r"(^\[\[\[)|(\]\]\]$)", ""), ", ")
)
df2.show()
#+----+------------------+--------------+
#|col1| col2| col3|
#+----+------------------+--------------+
#| a|[[[167, 109, 80]]]|[167, 109, 80]|
#+----+------------------+--------------+
df2.printSchema()
#root
# |-- col1: string (nullable = true)
# |-- col2: string (nullable = true)
# |-- col3: array (nullable = true)
# | |-- element: string (containsNull = true)
If you wanted the column as an array of integers, you could use cast:
from pyspark.sql.functions import col
df2 = df2.withColumn("col3", col("col3").cast("array<int>"))
df2.printSchema()
#root
# |-- col1: string (nullable = true)
# |-- col2: string (nullable = true)
# |-- col3: array (nullable = true)
# | |-- element: integer (containsNull = true)

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