mean and as.numeric functions not working-CodePudding

I'm just starting out with R and I'm practicing basic analysis with flight data. One of the columns in this df is the number of minutes a given flight was delayed. I tried finding the average using mean() but it's returning the error:

"argument is not numeric or logical: returning NA"

Obviously, this means this data is stored as something other than numbers; however, I've used as.numeric to change it to numbers (with no errors) and I used the str() function to verify that it's numbers and yet mean() is still not working. The weirdest part is that when I use the summary() function, it gives me the mean of that column! So R must know that there are numbers there! What is going on??

Here's a snippet of the data:

Origin Dest DelayMinutes chr chr dbl JFK FLL 5
LAS LAX 1

CodePudding user response：

Probably this column has NA values, so when you calculate the mean with mean() function you need to pass the na.rm = TRUE argument

mean(x, na.rm = T)

CodePudding user response：

Your syntax is incorrect, as you are essentially trying to get the mean of a string (e.g.,, mean("string")). So, you need to either get the mean of the column in base R or if you are wanting to use dplyr, then you need to use mutate.

So in base R, you could write like:

mean(delta_flights[,"DelayMinutes"], na.rm = T)
#[1] 3

# Or like this:
mean(delta_flights$DelayMinutes, na.rm = T)
#[1] 3

With dplyr, we could write like this to pipe into mutate:

library(dplyr)

delta_flights %>% 
  mutate(x = mean(DelayMinutes, na.rm = T))

Output

  Origin Dest DelayMinutes x
1    JFK  FLL            5 3
2    LAS  LAX            1 3

So, now if you can see that the results are the same as what you get with summary():

summary(delta_flights)

 #   Origin              Dest            DelayMinutes
 #Length:2           Length:2           Min.   :1    
 #Class :character   Class :character   1st Qu.:2    
 #Mode  :character   Mode  :character   Median :3    
 #                                      Mean   :3    
 #                                      3rd Qu.:4    
 #                                      Max.   :5