问题
I feel this should be something easy, I have looked x the internet, but I keep getting error messages. I have done plenty of analytics in the past but am new to R and programming.
I have a pretty basic function to calculate means x columns of data:
columnmean <-function(y){
nc <- ncol(y)
means <- numeric(nc)
for(i in 1:nc) {
means[i] <- mean(y[,i])
}
means
}
I'm in RStudio and testing it using the included 'airquality' dataset. When I load the AQ dataset and run my function:
data("airquality")
columnmean(airquality)
I get back:
NA NA 9.957516 77.882353 6.993464 15.803922
Because the first two variables in AQ have NAs in them. K, cool. I want to suppress the NAs such that R will ignore them and run the function anyway.
I am reading that I can specify this with na.rm=TRUE, like:
columnmean(airquality, na.rm = TRUE)
But when I do this, I get an error message saying:
"Error in columnmean(airquality, na.rm = TRUE) : unused argument (na.rm = TRUE)"
I'm reading all over the place that I simply need to include na.rm = TRUE and the function will run and ignore the NA values...but I keep getting this error. I have also tried use = "complete" and anything else I can find.
Two Caveats:
I know I can create a vector with is.na and then subset the data, but I don't want that extra step, I just want it to run the function and ignore the missing data.
I know also I can specify IN the function to ignore or not ignore, but I'd like a way to choose to ignore/not ignore on the fly, on a action by action basis, rather than having it be part of the function itself.
Help is appreciated. Thank you, everyone.
回答1:
We can include the na.rm = TRUE
in mean
columnmean <-function(y){
nc <- ncol(y)
means <- numeric(nc)
for(i in 1:nc) {
means[i] <- mean(y[,i], na.rm = TRUE)
}
means
}
If we need to use na.rm
argument sometimes as FALSE and other times as TRUE, then specify that in the argument of 'columnmean'
columnmean <-function(y, ...){
nc <- ncol(y)
means <- numeric(nc)
for(i in 1:nc) {
means[i] <- mean(y[,i], ...)
}
means
}
columnmean(df1, na.rm = TRUE)
#[1] 1.5000000 0.3333333
columnmean(df1, na.rm = FALSE)
#[1] 1.5 NA
data
df1 <- structure(list(num = c(1L, 1L, 2L, 2L), x1 = c(1L, NA, 0L, 0L
)), .Names = c("num", "x1"), row.names = c(NA, -4L), class = "data.frame")
回答2:
You should be using that parameter in the mean
function call:
columnmean <-function(y){
nc <- ncol(y)
means <- numeric(nc)
for(i in 1:nc) {
means[i] <- mean(y[,i], na.rm = TRUE)
}
means
}
columnmean
is a custom function and does not have that parameter.
回答3:
You can pass the parameter na.rm
to your function:
columnmean <- function(y, na.rm = FALSE){
nc <- ncol(y)
means <- numeric(nc)
for(i in 1:nc) {
means[i] <- mean(y[,i], na.rm = na.rm)
}
means
}
data("airquality")
columnmean(airquality, na.rm = TRUE)
#[1] 42.129310 185.931507 9.957516 77.882353 6.993464 15.803922
columnmean(airquality)
#[1] NA NA 9.957516 77.882353 6.993464 15.803922
But my recommendation is to look for an alternate code to loops:
column_mean <- function(y, na.rm = FALSE) {
sapply(y, function(x) mean(x, na.rm = na.rm))
}
column_mean(airquality, na.rm = TRUE)
# Ozone Solar.R Wind Temp Month Day
# 42.129310 185.931507 9.957516 77.882353 6.993464 15.803922
来源:https://stackoverflow.com/questions/43237325/issue-with-na-values-in-r