On 07/16/2013 06:36 AM, Steve Creamer wrote:
Dear All....I am really struggling with oo in R. Trying to set attributes of
the base class in a derived class method but the slot is only populated in
the method itself, not when I try to print out the object from the console.
Code is
library(RODBC)
#
# -----------------------------------------------------
# Define a medical event class. This is abstract (VIRTUAL)
# -----------------------------------------------------
#
setClass("Medical_Event",
representation(
Event_Name="character",
Capacity_Profile="numeric",
Delay_Profile="numeric",
"VIRTUAL"),
prototype(Event_Name="An
Event",Capacity_Profile=c(.2,.2,.2,.2,.2,0,0)))
setGeneric("getDelayProfile",function(object){standardGeneric("getDelayProfile")},simpleInheritanceOnly=T)
# ------------------------------------------
# Now define a derived class called GP_Event
# ------------------------------------------
setClass("GP_Event",representation(Surgery_Name="character"),contains=c("Medical_Event"),prototype(Surgery_Name="Unknown"))
# -----------------------------------------
# Now define a derived class called OP_Appt
# -----------------------------------------
setClass("OP_Appt",representation(Clinic_Name="character"),contains=c("Medical_Event"),prototype(Clinic_Name="Unknown"))
setMethod(f="getDelayProfile",signature("OP_Appt"),definition=function(object)
{
OpTablesDB<-odbcDriverConnect("DRIVER=Microsoft Access Driver (*.mdb,
*.accdb);
DBQ=Z:\\srp\\Development
Code\\Projects\\CancerPathwaySimulation\\Database\\CancerPathway.accdb")
strQuery<-"select * from op_profile"
odbcQuery(OpTablesDB,strQuery)
dfQuery<-odbcFetchRows(OpTablesDB)
odbcClose(OpTablesDB)
delay<-dfQuery$data[[1]][1:70]
prob<-dfQuery$data[[2]][1:70]
# as(object,"Medical_Event")@Delay_Profile<-prob
object@Delay_Profile <- prob
object
}
)
if I instantiate a new instance of the derived class
*aTest<-new("OPP_Appt")*and then try and populate the attribute
Delay_Profile by
*getDelayProfile(aTest) *
the object slot seems to be populated in the method because I can print it
out, viz
An object of class "OP_Appt"
Slot "Clinic_Name":
[1] "Unknown"
Slot "Event_Name":
[1] "An Event"
Slot "Capacity_Profile":
[1] 0.2 0.2 0.2 0.2 0.2 0.0 0.0
*Slot "Delay_Profile":
[1] 14 21 25 29 27 49 72 71 43 65 102 134 223 358 24 14 21 25
35 31 38 43 31 23 21 26 46 54 42 26
[31] 34 24 25 41 48 33 30 17 18 31 24 35 35 24 16 32 36 39
46 36 26 16 27 21 30 32 33 27 7 5
[61] 9 10 9 11 8 6 1 11 14 10*
but when the method returns and I type
*aTest*
I get
An object of class "OP_Appt"
Slot "Clinic_Name":
[1] "Unknown"
Slot "Event_Name":
[1] "An Event"
Slot "Capacity_Profile":
[1] 0.2 0.2 0.2 0.2 0.2 0.0 0.0
*Slot "Delay_Profile":
numeric(0)*
ie the Delay_Profile slot is empty????
What haven't I done - can anybody help me please?
It helps to provide a more minimal example, preferably reproducible (no data
base queries needed to illustrate your problem); I'm guessing that, just as with
f = funtion(l) { l$a = 1; l }
lst = list(a=0, b=1)
one would 'update' lst with
lst = f(lst)
and not
f(lst)
you need to assign the return value to the original object
aTest <- getDelayProfile(aTest)
Martin
Many Thanks
Steve Creamer
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and provide commented, minimal, self-contained, reproducible code.
