A reference class for storing and accessing data frames stored on disk.
FDF(df, backingfile = tempfile())
| df | A data frame. |
|---|---|
| backingfile | Path to the file storing the data on disk. Default stores in the temporary directory. |
An FDF object has many field:
$address: address of the external pointer containing the underlying
C++ object, to be used as a XPtr<FDF> in C++ code
$extptr: use $address instead
$nrow
$ncol
$types
$backingfile: File that stores the numeric data of the FDF
$rds: 'rds' file (that may not exist) in which this object is stored
$is_saved: whether this object stored in $rds?
$ind_row: Indices of rows for a subview of the FDF
$ind_col: Indices of columns for a subview view of the FDF
$strings: 2^16 strings to match with integers (between 0 and 65535)
$nstr: Number of unique strings already matched with an integer
$groups: Tibble with position indices of $ind_row for each group.
$groups_internal: use $groups instead
And some methods:
$save(): Save the FDF object in $rds. Returns the FDF.