warning message: NAs introduced by coercion

Question

I have uploaded csv file from Google trends into R and now I am trying to convert the format of the Year column to numeric values as it was identified as character (it was in the format as 2004-01) This is my R code: dataset1$Year <-as.numeric(dataset1$Year) And I receive this warning message: NAs introduced by coercion; and then all the dates are converted to NAs Does anyone know what's the problem is?

You may need to convert to Date class and then numeric or extract the first 4 characters as.numeric(substr(dataset1$Year, 1, 4)) — akrun

user2332849 user2332849 · Accepted Answer · 2020-03-16T21:55:27

Your read csv function probably converted the column to a factor. You can check if that is true by using the str() on your dataframe and checking the types of all fields.

If your column is a factor, it won't accept any new value beyond those initially established from reading the file. You can keep that from happing by putting the parameter stringsAsFactors = F in the function that reads your csv.

warning message: NAs introduced by coercion

1 Answers