Às 17:46 de 11/12/2022, akshay kulkarni escreveu:
Dear Rui,
Thanks for your reply....your reply covers the first part of
my question. What about the second part? i.e remembering the state when the
price q breaches Q? Will some thing like this work:
f <- function(envir) {expr1; expr2; expr3; envir$j <- envir$j + 1L}
e <- new.env()
e$j <- 1L
# do you need counter for something else?
# if not delete these two lines
counter <- list()
counter[[e$j]] <- 1L
# this seems to be all you need, not counter
if ((q >= Q) && e$j == 1L) {f(e); C1 <- "the price Q has been breached!"}
if(C1 != "the price Q has been breached!") { do something }
ANy other method?
Thanking you,
Yours sincerely,
AKSHAY M KULKARNI
________________________________
From: Rui Barradas <ruipbarra...@sapo.pt>
Sent: Sunday, December 11, 2022 10:58 PM
To: akshay kulkarni <akshay...@hotmail.com>; R help Mailing list
<r-help@r-project.org>
Subject: Re: [R] remembering the state of an action in R....
Às 17:11 de 11/12/2022, akshay kulkarni escreveu:
Dear members,
I am a stock trader and using R for my research.
I am monitoring stock prices in real time. I have the following code:
if (sock price q, breaches a certain value Q) { expr1; expr2; expr3}
THe point is, expr1,expr2,expr3 should execute only once, i.e when q breaches
Q. I thought of something like this:
if( q >= Q ) { expr1; expr2; expr3;}
But expressions keep repeating as long as q >= Q, NOT when q breaches Q for the
first time. I did some research on myself and came up with this:
f <- function() {expr1; expr2; expr3; j <<- j + 1}
j <- 1; counter[[j]] <- 1;
if ((q >= Q) && length(counter) == 1) {f}
I just want your help to know whether it is logically right or not. ARe not
there any other possibility other than using the superassignment operator?
Also, any way how to remember when the real time price q, breaches a value Q,
for the first time ( the price may come back to Q again afterwards) ?
THanking you,
Yours sincerely,
AKSHAY M KULKARNI
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Hello,
Use environments. You will assign to a variable living in a special
place, protected from the rest of the code, that you can access any time
you want.
Something like the following.
f <- function(envir) {expr1; expr2; expr3; envir$j <- envir$j + 1L}
e <- new.env()
e$j <- 1L
# do you need counter for something else?
# if not delete these two lines
counter <- list()
counter[[e$j]] <- 1L
# this seems to be all you need, not counter
if ((q >= Q) && e$j == 1L) {f(e)}
Hope this helps,
Rui Barradas
Hello,
Envirnments are still the solution for this. You can hold another
variable in the environment passed to f.
f <- function(real_time_price, Q_breach = Q, envir) {
envir$counter <- envir$counter + 1L
envir$breached <- "the price Q has been breached"
x <- pi
x
}
q <- 10
Q <- 5
e <- new.env()
e$counter <- 0L
# this seems to be all you need, not counter
if ((q >= Q) && e$counter == 0L) {
print(f(q, Q, envir = e))
}
if(e$breached != "the price Q has been breached!") {
message("do something...")
}
Hope this helps,
Rui Barradas
______________________________________________
R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
