How do I read a Parquet in R and convert it to an R DataFrame?
If you're using Spark then this is now relatively simple with the release of Spark 1.4 see sample code below that uses the SparkR package that is now part of the Apache Spark core framework.
# install the SparkR package
devtools::install_github('apache/spark', ref='master', subdir='R/pkg')
# load the SparkR package
library('SparkR')
# initialize sparkContext which starts a new Spark session
sc <- sparkR.init(master="local")
# initialize sqlContext
sq <- sparkRSQL.init(sc)
# load parquet file into a Spark data frame and coerce into R data frame
df <- collect(parquetFile(sq, "/path/to/filename"))
# terminate Spark session
sparkR.stop()
An expanded example is shown @ https://gist.github.com/andyjudson/6aeff07bbe7e65edc665
I'm not aware of any other package that you could use if you weren't using Spark.
You can use the arrow
package for this. It is the same thing as in Python pyarrow
but this nowadays also comes packaged for R without the need for Python.
git clone https://github.com/apache/arrow.git
cd arrow/cpp && mkdir release && cd release
# It is important to statically link to boost libraries
cmake .. -DARROW_PARQUET=ON -DCMAKE_BUILD_TYPE=Release -DARROW_BOOST_USE_SHARED:BOOL=Off
make install
Then you can install the R arrow
package:
devtools::install_github("apache/arrow/r")
And use it to load a Parquet file
library(arrow)
#>
#> Attaching package: 'arrow'
#> The following object is masked from 'package:utils':
#>
#> timestamp
#> The following objects are masked from 'package:base':
#>
#> array, table
read_parquet("somefile.parquet", as_tibble = TRUE)
#> # A tibble: 10 x 2
#> x y
#> <int> <dbl>
#> …