geslaR (version 1.0-1)

write_gesla: Write a GESLA dataset

Description

Write a CSV or Parquet file. Given an object x, this function will write a file in the appropriate format to store this object in the hard drive, facilitating it's reading in any other session.

The only accepted classes of x are ArrowObject or data.frame. If x is an ArrowObject, then the resulting file will have the .parquet extension, in the Apache Parquet file format. If x is a data.frame, the file will have a standard .csv extension.

This function is usefull to save objects created by the query_gesla() function, for example. However, it may be used in any case where saving a (possible subset) of the GESLA dataset may be needed.

Usage

write_gesla(x, file_name = "gesla-data", ...)

Value

A file with extension .csv, if x is a data.frame, or a file with extension .parquet, if x is an ArrowObject

Arguments

x

An object of class ArrowObject or data.frame

file_name

The name of the file to be created. Must be provided without extension, as this will be determined by the class of x.

...

Other arguments from arrow::write_csv_arrow(), and arrow::write_parquet(), from the arrow package.

Author

Fernando Mayer

Details

We highly recommend to always use the ArrowObject class, as it will be much more efficient for dealing with it in R. Also, the resulting file (with .parquet extension) from objects of this type will be much smaller than CSV files created from data.frame objects.

Examples

##------------------------------------------------------------------
## Import an internal example Parquet file
## Reading file
tmp <- tempdir()
file.copy(system.file(
    "extdata", "ireland.parquet", package = "geslaR"), tmp)
da <- read_gesla(paste0(tmp, "/ireland.parquet"))
## Generates a subset by filtering
db <- da |>
    filter(day == 1) |>
    collect()
## Save filtered data as file
write_gesla(db, file_name = paste0(tmp, "/gesla-data"))

##------------------------------------------------------------------
## Querying some data
## Make the query
if(interactive()) {
    da <- query_gesla(country = "IRL", year = 2019,
        site_name = "Dublin_Port")
    ## Save the resulting query to file
    write_gesla(da, file_name = paste0(tmp, "/gesla-data"))
}

## Remove files from temporary directory
unlink(paste0(tmp, "/gesla-data.csv"))
unlink(paste0(tmp, "/gesla-data.parquet"))
unlink(paste0(tmp, "/ireland.parquet"))