| [[.big.data.table {big.data.table} | R Documentation |
Extract from big.data.table
## S3 method for class 'big.data.table'
x[[j, expr, lazy = TRUE, send = FALSE, i, ...,
simplify = TRUE, rbind = TRUE, parallel = TRUE,
outer.aggregate = getOption("bigdatatable.outer.aggregate", FALSE),
.log = getOption("bigdatatable.log", FALSE)]]
x |
big.data.table object. |
j |
numeric scalar, if provided then all other arguments are ignored and subset behaves the same way as for data.table, but returns 0 length column. |
expr |
expression to be evaluated on node where data.table objects are stored as 'x' variable in '.GlobalEnv'. |
lazy |
logical if TRUE then *expr* is substituted. |
send |
logical, if TRUE submit expression appended with 'TRUE' to not fetch potentially big results from provided *expr*, useful for data.table __set*__ or ':=' functions. |
i |
numeric restrict expression to particular nodes |
simplify |
logical passed to 'bdt.eval', affects the type of returned object. |
rbind |
logical passed to 'bdt.eval', affects the type of returned object. |
parallel |
logical if parallel *TRUE* (default) it will send expression to nodes using 'wait=FALSE' and collect results afterward executing each node in parallel. |
outer.aggregate |
logical or a function, if *TRUE* will able the same query to rbind of results from each node, should not be used with '.SD', '.N', etc. Also conflicts with filtering in 'i'. Can be also a function taking first argument 'x' rbinded data.table. |
.log |
logical if *TRUE* then logging will be done using logR to postgres db. |
... |
ignored. |
When using *j* arg the 0 length variable from underlying data is returned. Otherwise the results from expression evaluated as *lapply*. When using *rbind* or *simplify* the returned list be can simplified.