readfst {hdd} | R Documentation |
Read fst or HDD files as DT
Description
This is the function read_fst
but with automatic conversion
to data.table. It also allows to read hdd
data.
Usage
readfst(path, columns = NULL, from = 1, to = NULL, confirm = FALSE)
Arguments
path |
Path to |
columns |
Column names to read. The default is to read all columns. Ignored
for |
from |
Read data starting from this row number. Ignored for |
to |
Read data up until this row number. The default is to read to the last
row of the stored data set. Ignored for |
confirm |
If the HDD file is larger than ten times the variable |
Details
This function reads one or several .fst
files and place them in a single
data table.
Value
This function returns a data table located in memory. It allows to read in memory
the hdd
data saved on disk.
Author(s)
Laurent Berge
See Also
See hdd
, sub-.hdd
and cash-.hdd
for the extraction and manipulation of out of memory data. For importation of
HDD data sets from text files: see txt2hdd
.
See hdd_slice
to apply functions to chunks of data (and create
HDD objects) and hdd_merge
to merge large files.
To create/reshape HDD objects from memory or from other HDD objects, see
write_hdd
.
To display general information from HDD objects: origin
,
summary.hdd
, print.hdd
,
dim.hdd
and names.hdd
.
Examples
# Toy example with the iris data set
# writing a hdd file
hdd_path = tempfile()
write_hdd(iris, hdd_path, rowsPerChunk = 30)
# reading the full data in memory
base_mem = readfst(hdd_path)
# is equivalent to:
base_hdd = hdd(hdd_path)
base_mem_bis = base_hdd[]