Clash Royale CLAN TAG#URR8PPP

How to optimize this nested for loop in R?

I need help figuring out how to improve a for loop. It doesn't necessarily needs to be an apply, I just thought it was the best way after researching it on stackoverflow. I tried following the guides I found on stackoverflow, but i'm a newbie and believe i'm not getting a good grasp on the apply function.

This is a reconstruction of the snippet i'm trying to change:

for (j in 1:NROW(teste2) {
for (z in 1:NROW(teste2)) z==NROW(teste2))
teste2$SALDO[z] <- 0
else
if(teste2$SALDO[z]!=0 & teste2$DATE[z]==Sys.Date()+j-1)
teste2$SALDO[z+1] <- teste2$PREVISAO_FINAL2[z] + teste2$SALDO[z+1]
else
teste2$SALDO[z] <- teste2$SALDO[z]





i tried doing the following:

for (j in 1:NROW(teste2)
rows = 1:NROW(teste2)
saldo_fn <- function(z) z==NROW(teste2))
teste2$SALDO[z] <- 0
else
if(teste2$SALDO[z]!=0 & teste2$DATE[z]==Sys.Date()+j-1)
teste2$SALDO[z+1] <- teste2$PREVISAO_FINAL2[z] + teste2$SALDO[z+1]
else
teste2$SALDO[z] <- teste2$SALDO[z]

)

teste2$SALDO <- sapply(rows, saldo_fn)



but when i run sum(teste2$SALDO) it gives a different value.

What am I doing wrong? how do I fix it?

1 Answer
1

You cannot use apply-family function to optimize the algorithm. The reason is the line:

apply

teste2$SALDO[z+1] <- teste2$PREVISAO_FINAL2[z] + teste2$SALDO[z+1]


You are recursively changing the value of next element based on the value of current one.

It is possible avoid for-loop in by using recursion, i.e. if you see something like x[i+1] = x[i+1] + x[i] you should use either for-loops or recursive functions (I prefer for-loops they are much easier and there is no problem with call stack overflow), if you see something like z[i] = F(x[i], y[i]), where F is some function, you can use apply-family functions.

for

x[i+1] = x[i+1] + x[i]

for

for

z[i] = F(x[i], y[i])

apply

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