remembering the state of an action in R....

?s 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

????[[alternative HTML version deleted]]

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