R equivalent of performing operations on an empty list in Python?-CodePudding

I have been trying to replicate code in python to the R equivalent, but am having some troubles. I am trying to add a vector to an empty list, it seems like this can be easily done in python, but finding the correct empty list in R is challenging.

I think the issue with the R equivalent is determining the correct empty list for S1 with the same vector length as P and E, as python seems to do this stress free. I have tried using vector() and rep() functions and specifying the desired length of 731, but R wont let me perform any operations on it and the error message is rightly Error in S1[i - 1] DS : non-numeric argument to binary operator. Was there a simple way to make an empty list numeric in this regard?

Note that the depicted P and E correspond to external rainfall data (from a CSV) with a length of 731.

The python equivalent is shown below:

A1 = float(0.134) 
A2 = float(0.433)     
A3 = float(0.433)
C1 = float(7)
C2 = float(70)  
C3 = float(150)

S1 = []; S2 = []; S3 = []
Total_Excess = []

for i in range(1,dims[0]):
    dS = P[i]-E[i] 
    
    S1_temp = max(S1[i-1] dS,0)
    S1_Excess = max(S1_temp-C1,0)
    S1.append(min(S1_temp,C1))
    
    S2_temp = max(S2[i-1] dS,0)
    S2_Excess = max(S2_temp-C2,0)
    S2.append(min(S2_temp,C2))
    
    S3_temp = max(S3[i-1] dS,0)
    S3_Excess = max(S3_temp-C3,0)
    S3.append(min(S3_temp,C3))
    
    Total_Excess.append((S1_Excess*A1) (S2_Excess*A2) (S3_Excess*A3))

The R code that I had written before I got stuck is shown below:

A1 <- 0.4
A2 <- 0.4
A3 <- 0.2

C1 <- 10
C2 <- 75
C3 <- 200

S1 <- list()
S2 <- list()
S3 <- list()

for(i in 1:nrow(df)){
  DS <- P - E
  
  S1_temp <- max(S1[i-1]  DS, 0)
  S1_excess <- max(S1_temp - C1)
  append(S1, min(S1_temp,C1))

  S2_temp <- max(S2[i-1]  DS, 0)
  S2_excess <- max(S1_temp - C1)
  append(S2, min(S1_temp,C1))
  ...

Once the first portion is run, I call S1_temp in the console and only get a vector of length = 1 back, which should evidently be of length = 731.

Also, how would I go about appending the Total_excess empty list to the resulting vector as seen in the last line of code in the python code example??

Any assistance would be greatly appreciated.

CodePudding user response：

The equivalent of Python S1 = []; S1.append(x) in R is S1 <- list(); S1 <- c(S1, list(x)) in R.

In your example c(S1, x) will work because the numeric value you are trying to append will be automatically wrapped in a list, but it's safer to do it explicitly. If x is already a list, then c(S1, x) will append its elements to S1, while c(S1, list(x)) will append a single entry containing a copy of x to S1.

You could use the append() function in R, but then remember that it's rare for R functions to modify their arguments, so you would write

S1 <- append(S1, list(x))

In this situation it's essentially identical to c().