read.quitte: Read IAMC-style .csv or .xlsx files, or object from rds file.

In pik-piam/quitte: Bits and pieces of code to use with quitte-style data frames

Read IAMC-style .csv or .xlsx files, or object from rds file.

Description

Reads IAMC-style .csv or .xlsx files or object from rds file into a quitte data frame.

Usage

read.quitte(
  file,
  sep = NULL,
  quote = "",
  na.strings = c("UNDF", "NA", "N/A", "n_a"),
  convert.periods = FALSE,
  check.duplicates = TRUE,
  factors = TRUE,
  drop.na = FALSE,
  comment = "#",
  filter.function = identity,
  chunk_size = 200000L
)

Arguments

file	Path of IAMC-style .csv, .xlsx, or rds file or vector of paths to read.
sep	Column separator, defaults to ";" in read_mif_header().
quote	Quote characters, empty by default.
na.strings	Entries to interpret as NA; defaults to c("UNDF", "NA", "N/A", "n_a")
convert.periods	If TRUE, periods are converted to POSIXct. If FALSE (the default), periods are numerical.
check.duplicates	If TRUE a duplicates check will be performed on the data. For time- and memory-critical applications this can be switched off.
factors	Return columns as factors (TRUE, the default) or not.
drop.na	Should NA values be dropped from the quitte?
comment	A character which at line start signifies the optional comment header with metadata at the head of file. The comment header, if present, is returned as a comment_header attribute. If multiple files are read, the comment_header attribute is a list of comment headers with file paths as names.
filter.function	A function used to filter data during read. See Details.
chunk_size	Number of lines to read at a time. Defaults to 200000. (REMIND .mif files have between 55000 and 105000 lines for H12 and EU21 regional settings, respectively.)

Details

In order to process large data sets, like IIASA data base snapshots, read.quitte() reads provided files in chunks of chunk_size lines (not for Excel files), and applies filter.function() to the chunks. This allows for filtering data piece-by-piece, without exceeding available memory. filter.function is a function taking one argument, a quitte data frame of the read chunk, and is expected to return a data frame. Usually it should simply contain all the filters usually applied after all the data is read in. Suppose there is a file big_IIASA_snapshot.csv, from which only data for the REMIND and MESSAGE models between the years 2020 to 2050 is of interest. Normally, this data would be processed as

read.quitte(file = 'big_IIASA_snapshot.csv') %>%
    filter(grepl('^(REMIND|MESSAGE)', .data$model),
           between(.data$period, 2020, 2060))

If however big_IIASA_snapshot.csv is too large to be read in completely, it can be read using

read.quitte(file = 'big_IIASA_snapshot.csv',
            filter.function = function(x) {
                x %>%
                    filter(grepl('^(REMIND|MESSAGE)', .data$model),
                           between(.data$period, 2020, 2060))
            })

Value

A quitte data frame.

Author(s)

Michaja Pehl

Examples

## Not run: 
read.quitte(c("some/data/file.mif", "some/other/data/file.mif"))
read.quitte("some/data/file.csv", sep = ",", quote = '"')

## End(Not run)

pik-piam/quitte documentation built on April 12, 2025, 5:49 p.m.