importDT: Import a file to data.table

In CALIBERdatamanage: Data Management Tools for CALIBER Datasets

Description

Imports a text or Stata file to data.table, automatically converting dates

Usage

importDT(filename, datecolnames = NULL,
    verbose = TRUE, sep = NULL, zipname = NULL,
    key = NULL, convertLogical = TRUE, fread = TRUE,
    nrows = NULL, ...)

Arguments

filename	a single filename or path to a text file, Stata file, gz compressed text file or a zip file containing one file.
datecolnames	an argument passed to convertDates to convert relevant columns to IDate. It can be either a vector of date column names, or an empty string (for no dates to be converted) or NULL if an attempt should be made to convert all columns. Columns which cannot be coerced to date are left unchanged.
verbose	whether to print information about the file loaded
sep	a single delimiter character. If NULL, the function will try to detect it (, ; or TAB) from the first line.
zipname	path to a zip file. This is only required if the zip file contains more than one file, otherwise the path to the zip file can be supplied as the filename argument.
key	a character vector of key column names, to set the data.table key
convertLogical	whether to convert 1 / 0 columns to logical
fread	whether to use the new fread fast file loader in data.table. It is not used if nrows is supplied, because fread loads the entire file. This function cannot currently handle escaped quotes, so if the input file contains escaped quotes, set fread to FALSE.
nrows	number of rows to import, default (NULL) is to import all rows.
...	other arguments to pass to read.dta, fread or read.delim.

Details

A convenience function for importing a text file, including handling zip compressed files, automatically detecting the delimiter and converting dates.

Value

A data.table containing the imported data.

Note

In the future this function may be updated to take advantage of the new fread function in the data.table package.

Author(s)

Anoop Shah

See Also

importFFDF

Examples

# Import a test dataset
data(test_data)
tempfile <- paste(tempdir(), '/tmp.csv', sep = '')
write.csv(test_data, tempfile, row.names = FALSE)

# Default (fread = TRUE)
importDT(tempfile)
# Using the older read.delim function
importDT(tempfile, fread = FALSE)
# Limiting the number of rows
importDT(tempfile, nrows = 3)

# Convert to FFDF
as.ffdf(importDT(tempfile))

# Importing another test dataset
data(test_import)
write.csv(test_import, tempfile, row.names = FALSE)
importDT(tempfile)
# datenotok is not converted because of an error
str(importDT(tempfile))

# Importing only one row (nrows is an argument to read.delim)
importDT(tempfile, nrows = 1)
unlink(tempfile)

# Importing Stata file
tempstata <- paste(tempdir(), '/tmp.dta', sep = '')
write.dta(test_data, tempstata)
importDT(tempstata)
unlink(tempstata)

CALIBERdatamanage documentation built on Nov. 23, 2021, 3 p.m.