Looping through numerous functions with a vector of characters - r

Question

I thought this would be easier than it is, but I am learning to code in R so looping is certainly not my strong point.
What I am attempting to do here is take a series of functions that all have a common theme of MISO. As you can see in the first batch of code below MISO is common, but I would like to swap the MISO for i as one would do in a for loop and then loop through a few different names in a character vector. Let's call that character vector ID so that ID <- c("MISO","PJM","SERC")
At this point in the code, all_Cities_MISO is already a data frame in my environment. I just want to break it up and perform some calculations.
meanAvgHighMISO <- mean(all_Cities_MISO$Col21)
meanAvgLowMISO <- mean(all_Cities_MISO$Col20)
meanAvgMISO <- mean(cbind(meanAvgHighMISO,meanAvgLowMISO))
names(meanAvgMISO) <- ifelse(meanAvgMISO<65,"HDD","CDD")
MISO_Avg_DD <- ifelse(meanAvgMISO<65,(65-meanAvgMISO),(meanAvgMISO-65)) #average degree days for each period
MISO_op_mean <- apply(all_Cities_MISO[,1:19],2, mean)
So I attempted this a few different times, but keep getting errors like Error: unexpected string constant in:
" meanAvgHigh"i""
I feel like it should be simple to replace the MISO with a PJM throughout the code above with a simple for loop, but no luck. It must be something with it not liking MISO as a character.
Here is my attempt at the for loop:
ID <- c("MISO","PJM","SERC")
for(i in ID){
meanAvgHigh"i" <- mean(all_Cities_"i"$Col21)
meanAvgLow"i" <- mean(all_Cities_"i"$Col20)
meanAvg"i" <- mean(cbind(meanAvgHigh"i",meanAvgLow"i"))
names(meanAvg"i") <- ifelse(meanAvg"i"<65,"HDD","CDD")
"i"_Avg_DD <- ifelse(meanAvg"i"<65,(65-meanAvg"i"),(meanAvg"i"-65)) #average degree days for each period
"i"_op_mean <- apply(all_Cities_"i"[,1:19],2, mean)
}
I attempted using [i] instead of "i", but that didn't work either. I understand that MISO itself in the first code I displayed is not a character, but I'm not sure how R would recognize it in the loop otherwise... I just would like to do a simple swap of names in a loop. MISO for PJM or for SERC etc etc.
Any help is greatly appreciated, thank you.

Answer 1

While you can do that by using the environment() and assign() methods, I would advise against it. You should instead use a nested list to save those values.
However, for completeness, this is how I think one would do it (untested):
env <- environment()
ID <- c("MISO","PJM","SERC")
for(i in ID){
assign(paste0("meanAvgHigh", i), mean(env[[ paste0("all_Cities_", i) ]]$Col21))
assign(paste0("meanAvgLow", i), mean(env[[ paste0("all_Cities_", i) ]]$Col20))
assign(paste0("meanAvg", i), mean(cbind(env[[ paste0("meanAvgHigh", i) ]], env[[ paste0("meanAvgLow", i) ]])))
names(env[[ paste0("meanAvg", i) ]]) <- ifelse(env[[ paste0("meanAvg", i) ]] < 65,"HDD","CDD")
##### Note: The ifelse can probably be replaced by an abs
assign(paste0(i, "_Avg_DD"), ifelse( env[[ paste0("meanAvg", i) < 65,
(65 - env[[ paste0("meanAvg", i) ]]),
(env[[ paste0("meanAvg", i) ]] - 65)
)) #average degree days for each period
assign(paste0(i, "_op_mean"), apply(env[[ paste0("all_Cities_", i) ]][,1:19], 2, mean)
}
The basic idea is using assign to set the values in the current environment and then using the current environment env to get them via indexing.