csv: Read and Write a Comma Separated File

In fritools: Utilities for the Forest Research Institute of the State Baden-Wuerttemberg

Read and Write a Comma Separated File

Description

Functions to read and write CSV files. The objects returned by these functions are data.frames with the following attributes:

path

The path to the file on disk.

csv

The type of CSV: either standard or german.

hash

The hash value computed with digest's digest function, if digest is installed.

read_csv is a wrapper to determine whether to use utils:read.csv2 or utils:read.csv. It sets the above three arguments.

write_csv compares the hash value stored in the object's attribute with the objects current hash value. If they differ, it writes the object to the file argument or, if not given, to the path stored in the object's attribute. If no csv_type is given, it uses the csv type stored in object's attribute. If digest is not installed, the object will (unconditionally) be written to disk.

Usage

read_csv(file, ...)

write_csv(x, file = NULL, csv_type = c(NA, "standard", "german"))

Arguments

file	The path to the file to be read or written.
...	Arguments passed to utils::read.csv or utils::read.csv2.
x	The object to write to disk.
csv_type	Which csv type is to be used. If NA, the csv attribute is read from the object.

Value

For read_csv: An object read from the file.

For write_csv: The object with updated hash (and possibly path and csv) attribute.

See Also

Other CSV functions: bulk_read_csv(), bulk_write_csv(), check_ascii_file(), csv2csv()

Examples

# read from standard CSV
f <- tempfile()
write.csv(mtcars, file = f)
str(read_csv(f))
f <- tempfile()
write.csv2(mtcars, file = f)
str(read_csv(f))
# write to standard CSV
f <- tempfile()
d <- mtcars
str(d <- write_csv(d, file = f))
file.mtime(f)
Sys.sleep(2) # make sure the mtime would have changed
write_csv(d, file = f)
file.mtime(f)

fritools documentation built on Nov. 19, 2023, 1:06 a.m.