existHistory {msProcess} | R Documentation |
Checks for the existence of an object of class eventHistory
attached an as attribute to the input object. Additionally,
the user can seek the existence of a particular event within
that history.
existHistory(x, event=NULL)
x |
an object of arbitrary class. |
event |
a character string defining a registered event to query.
If no such event has been registered in a history object (or the history
object does not exist) then a FALSE is returned. Default: NULL
(do not search for a specific event). |
a logical value. A TRUE
value is returned if a history object
exists as an attribute of the primary input object x
.
If event
is also specified, the output will be a logical value
defining whether or not that event has been registered in the
history object.
assignEvent
, isProcessRecorded
, getHistory
, eventHistory
.
## check for the existence of a registered history ## in an object without one (FALSE) z <- 1:5 existHistory(z) ## create a simple history z <- eventHistory(z, "Event A"=list(number="first", positive="yes"), "Event B"=list(horse="mustang")) ## check for a registered history (TRUE) existHistory(z) ## check to see if "Event A" has been registered ## (TRUE) existHistory(z,"Event A") ## check to see if "Event D" has been registered ## (FALSE) existHistory(z,"Event D")