Sets/gets the size cap when extracting hdd data

Sets/gets the default size cap when extracting HDD variables with cash-.hdd or when importing full HDD data sets with readfst.

setHdd_extract.cap(sizeMB = 3000)

getHdd_extract.cap

Format

An object of class function of length 1.

Arguments

sizeMB

Size cap in MB. Default is 3000.

Value

The size cap, a numeric scalar.

Details

In readfst, if the expected size of the data set exceeds the cap then, in interactive mode, a confirmation is asked. When not in interactive mode, no confirmation is asked. This can also be bypassed by using the argument confirm.

Examples

# Toy example with iris data
# We first create a hdd dataset with approx. 100KB
hdd_path = tempfile() # => folder where the data will be saved
write_hdd(iris, hdd_path)
for(i in 1:10) write_hdd(iris, hdd_path, add = TRUE)

base_hdd = hdd(hdd_path)
summary(base_hdd) # => 11 files
#> Hard drive data of 48.7 KB. Made of 11 files.
#> Location: C:/Users/lrberge/AppData/Local/Temp/Rtmpa0wfuK/file56884ca51dd4/
#> 1650 lines, 5 variables.

# we can extract the data from the 11 files with '$':
pl = base_hdd$Sepal.Length

#
# Illustration of the protection mechanism:
#

# By default when extracting a variable with '$'
# and the size exceeds the cap (default is greater than 3GB)
# a confirmation is needed.
# You can set the cap with setHdd_extract.cap.

# Following code asks a confirmation:
setHdd_extract.cap(sizeMB = 0.005) # new cap of 5KB
try(pl <- base_hdd$Sepal.Length)

# To extract the variable without changing the cap:
pl = base_hdd[, Sepal.Length] # => no size control is performed

# Resetting the default cap
setHdd_extract.cap()