mean.default argument not numerical on R

Question

I'm trying to use R for the first time, I have never taken courses and have some questions. the first is this: when I try to do the mean of some Temperature values (they are all between 18.15 and 18.40) I get this answer "Warning message: In mean.default(d_Temp_Experiment$value) : argument is not numeric or logical: returning NA" I dont' have the same problem with values of PAR 5that are all integer numbers and with values of pH all decimal numbers like 8.831... Can you tell what I do wrong?

Answer 1

As Arun hints at it could be that the column is character rather than numeric. If you are sure that all the values are correct you could coerce the values with

d_Temp_Experiment$value <- as.numeric(d_Temp_Experiment$value)

You might have the below sort of business going on.

myvector <- c(0,1,2,3,4,5,"6","7")
mv <- as.numeric(myvector)
mean(myvector)
mean(mv)