README.md

In Emaasit/sparkxml: Read xml data files into Spark DataFrames

Read xml data files into Spark DataFrames

What is sparkxml?

sparkxml is an extension for sparklyr to read xml data files into Spark DataFrames. It uses the Spark package spark-xml to load xml data into Spark DataFrames.

Installation

sparkxml requires the sparklyr package to run

Install sparklyr

I recommend the latest stable version of sparklyr available on CRAN

install.packages("sparklyr")

Install sparkxml

Install the development version of sparkxml from this Github repo using devtools

library(devtools)
devtools::install_github("emaasit/sparkxml")

Connecting to Spark

If Spark is not already installed, use the following sparklyr command to install your preferred version of Spark:

library(sparklyr)
spark_install(version = "2.0.0")

The call to library(sparkxml) will make the sparkxml functions available on the R search path and will also ensure that the dependencies required by the package are included when we connect to Spark.

library(sparkxml)

We can create a Spark connection as follows:

sc <- spark_connect(master = "local")

Reading xml files

sparkxml provides the function spark_read_xml to read xml data files in .xml format into Spark DataFrames. It uses a Spark package called spark-xml. Here's an example.

In the example below, we read a xml data file called books.xml into a table called xml_table in Spark. This file is available here.

$ wget https://github.com/databricks/spark-xml/raw/master/src/test/resources/books.xml

books_file <- system.file("extdata", "books.xml", package = "sparkxml")

books_df <- spark_read_xml(sc, path = books_file, table = "xml_table")
books_df

The resulting pointer to a Spark table can be further used in dplyr statements.

library(dplyr)
books_df %>% group_by(genre) %>%
  summarise(count = n(), avg.price = mean(price))

Logs & Disconnect

Look at the Spark log from R:

spark_log(sc, n = 100)

Now we disconnect from Spark:

spark_disconnect(sc)

Acknowledgements

Thanks to RStudio for the sparklyr packages that provides functionality to create Extensions.

Emaasit/sparkxml documentation built on May 6, 2019, 3:47 p.m.