R modify a column only if it exists - r

Question

Suppose I have the following code snippet:
mainResult$Time <- formatTime(mainResult$Time, "DateAndTime")
mainResult$SettleDate <- formatTime(mainResult$SettleDate, "DateAndTime")
mainResult$IssueDate <- formatTime(mainResult$IssueDate, "DateAndTime")
mainResult$Maturity <- formatTime(mainResult$Maturity, "DateAndTime")
mainResult$Bid <- formatNumber(mainResult$Bid, "withDecimals")
mainResult$Ask <- formatNumber(mainResult$Ask, "withDecimals")
mainResult$AvgBid <- formatNumber(mainResult$AvgBid, "withDecimals")
mainResult$AvgAsk <- formatNumber(mainResult$AvgAsk, "withDecimals")
mainResult$BidYield <- formatNumber(mainResult$BidYield, "withDecimals")
mainResult$AskYield <- formatNumber(mainResult$AskYield, "withDecimals")
mainResult$BidSize <- formatNumber(mainResult$BidSize, "noDecimals")
mainResult$AskSize <- formatNumber(mainResult$AskSize, "noDecimals")
mainResult$Coupon <- formatNumber(mainResult$Coupon, "withDecimals")
Each formatTime and formatNumber works fine only if the column exists. Is there a clean way for this to execute without me wrapping every statement in an if block that checks if the column exists?

Answer 1

This is a terrible way to code. Try to use something more like this:
# start with a vector of column names and loop
dt_columns = c("Time", "SettleDate", "IssueDate", "Maturity")
for (col in dt_columns) {
if (col %in% names(mainResult)) mainResults[[col]] = formatNumber(mainResult[[col]], "DateAndTime")
}
# you can repeat for your other cases
Or this:
# intersect and lapply
dt_columns = c("Time", "SettleDate", "IssueDate", "Maturity")
dt_columns = intersect(names(mainResults), dt_columns)
mainResult[dt_columns] = lapply(mainResult[dt_columns], formatNumber, "DateAndTime")

Answer 2

I'd probably start by separating the information about the transformations you want to perform to the columns from the code that does the transformation. Something more like this
numberWithDecimals <- c("Bid","Ask","AvgBid","AvgAsk", "BidYield", "AskYield", "Coupon")
numberNoDecimals <- c("BidSize", "AskSize")
timeDateAndTime <- c("Time", "SettleDate", "IssueDate", "Maturity")
fmtColumns <- function(data, txlist, fun, fmt) {
cols <- intersect(txlist, names(data))
if(length(cols) > 0) {
data[, cols, drop=F] <- lapply(data[, cols, drop=F], fun, fmt)
}
}
mainResult <- fmtColumns(mainResult, numberWithDecimals, formatNumber, "withDecimals")
mainResult <- fmtColumns(mainResult, numberNoDecimals, formatNumber, "noDecimals")
mainResult <- fmtColumns(mainResult, timeDateAndTime , formatTime, "DateAndTime")