R help - Dec 2022 - remembering the state of an action in R....

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]]

?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]]
> 
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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