How to transform values below from multiple XML files to spark data frame :
Id0
from Level_0
Date
/Value
from Level_4
Required output:
+----------------+-------------+---------+
|Id0 |Date |Value |
+----------------+-------------+---------+
|Id0_value_file_1| 2021-01-01 | 4_1 |
|Id0_value_file_1| 2021-01-02 | 4_2 |
|Id0_value_file_2| 2021-01-01 | 4_1 |
|Id0_value_file_2| 2021-01-02 | 4_2 |
+----------------+-------+---------------+
file_1.xml:
<Level_0 Id0="Id0_value_file1">
<Level_1 Id1_1 ="Id3_value" Id_2="Id2_value">
<Level_2_A>A</Level_2_A>
<Level_2>
<Level_3>
<Level_4>
<Date>2021-01-01</Date>
<Value>4_1</Value>
</Level_4>
<Level_4>
<Date>2021-01-02</Date>
<Value>4_2</Value>
</Level_4>
</Level_3>
</Level_2>
</Level_1>
</Level_0>
file_2.xml:
<Level_0 Id0="Id0_value_file2">
<Level_1 Id1_1 ="Id3_value" Id_2="Id2_value">
<Level_2_A>A</Level_2_A>
<Level_2>
<Level_3>
<Level_4>
<Date>2021-01-01</Date>
<Value>4_1</Value>
</Level_4>
<Level_4>
<Date>2021-01-02</Date>
<Value>4_2</Value>
</Level_4>
</Level_3>
</Level_2>
</Level_1>
</Level_0>
Current Code Example:
files_list = ["file_1.xml", "file_2.xml"]
df = (spark.read.format('xml')
.options(rowTag="Level_4")
.load(','.join(files_list))
Current Output:(Id0
column with attributes missing)
+-------------+---------+
|Date |Value |
+-------------+---------+
| 2021-01-01 | 4_1 |
| 2021-01-02 | 4_2 |
| 2021-01-01 | 4_1 |
| 2021-01-02 | 4_2 |
+-------+---------------+
There are some examples, but non of them solve the problem: -I'm using databricks spark_xml - https://github.com/databricks/spark-xml -There is an examample but not with attribute reading, Read XML in spark, Extracting tag attributes from xml using sparkxml .
EDIT:
As @mck pointed out correctly <Level_2>A</Level_2>
is not correct XML format. I had a mistake in my example(now xml file is corrected), it should be <Level_2_A>A</Level_2_A>
. After that , proposed solution works even on multiple files.
NOTE: To speedup loading of large number of xmls define schema, if no schema is defined spark is reading each file when creating dataframe to interfere schema... for more info: https://szczeles.github.io/Reading-JSON-CSV-and-XML-files-efficiently-in-Apache-Spark/
STEP 1):
files_list = ["file_1.xml", "file_2.xml"]
# for schema seem NOTE above
df = (spark.read.format('xml')
.options(rowTag="Level_0")
.load(','.join(files_list),schema=schema))
df.printSchema()
root
|-- Level_1: struct (nullable = true)
| |-- Level_2: struct (nullable = true)
| | |-- Level_3: struct (nullable = true)
| | | |-- Level_4: array (nullable = true)
| | | | |-- element: struct (containsNull = true)
| | | | | |-- Date: string (nullable = true)
| | | | | |-- Value: string (nullable = true)
| |-- Level_2_A: string (nullable = true)
| |-- _Id1_1: string (nullable = true)
| |-- _Id_2: string (nullable = true)
|-- _Id0: string (nullable = true
STEP 2) see below @mck solution:
You can use Level_0
as the rowTag, and explode the relevant arrays/structs:
import pyspark.sql.functions as F
df = spark.read.format('xml').options(rowTag="Level_0").load('line_removed.xml')
df2 = df.select(
'_Id0',
F.explode_outer('Level_1.Level_2.Level_3.Level_4').alias('Level_4')
).select(
'_Id0',
'Level_4.*'
)
df2.show()
+---------------+----------+-----+
| _Id0| Date|Value|
+---------------+----------+-----+
|Id0_value_file1|2021-01-01| 4_1|
|Id0_value_file1|2021-01-02| 4_2|
+---------------+----------+-----+