Creates a new named filter

Creates a new named filter.

emr_filter.create(
  filter,
  src,
  keepref = FALSE,
  time.shift = NULL,
  val = NULL,
  expiration = NULL,
  operator = "="
)

Arguments

filter

filter name. If NULL - a name would be generated automatically using emr_filter.name.

src

source (track name, virtual track name or id-time table). Can be a vector of track names.

keepref

'TRUE' or 'FALSE'

time.shift

time shift and expansion for iterator time

val

selected values

expiration

expiration period

operator

operator for filtering. Accepts one of: "=", "<", "<=", ">", ">="

Value

Name of the filter (invisibly, if filter name wasn't generated automatically, otherwise - explicitly)

Details

This function creates a new named filter.

'src' can be either a track name, a virtual track name, or an id-time table - data frame with the first columns named "id", "time" and an optional "ref".

If 'val' is not 'NULL', the time window of the filter is required to contain at least one value from the vector of 'val' which passes the 'operator' (see below).

'val' is allowed to be used only when 'src' is a name of a track. When val is specified, the filter will filter the i.d, time points by applying the 'operator' argument on the value of the point.

If 'expiration' is not 'NULL' and the filter window contains a value at time 't', the existence of previous values in the time window of [t-expiration, t-1] (aka: "expiration window") is checked. If no such values are found in the expiration window, the filter returns 'TRUE', otherwise 'FALSE'.

'expiration' is allowed to be used only when 'src' is a name of a categorical track and 'keepref' is 'FALSE'.

'operator' corresponds to the 'val' argument. The point passes the filter if the point's value passes the operator. For example if the point's value is 4, the operator is "<" and val is 5, the expression evaluated is 4 < 5 (pass). When 'operator' is not "=", 'vals' must exist, and be of length 1.

If both 'val' and 'expiration' are not 'NULL' then only values from 'val' vector are checked both in time window and expiration window.

Note: 'time.shift' can be used only when 'keepref' is 'FALSE'. Note: A zero length vector is interpreted by R as NULL, so val=c() would create a filter which returns all the values of src

See also

emr_filter.attr.src, emr_filter.ls, emr_filter.exists, emr_filter.rm, emr_filter.create_from_name

Examples

emr_db.init_examples()
#> NULL
emr_filter.create("f1", "dense_track", time.shift = c(2, 4))
emr_filter.create("f2", "dense_track", keepref = TRUE)
emr_extract("sparse_track", filter = "!f1 & f2")
#>   id time ref sparse_track
#> 1 25   12  -1          124
#> 2 27   23  -1          234