Dealing with missing values
Missing values are often encoded differently. In some files, -9999 mean missing values and in others, they may be encoded as #$##. You can use the na.strings argument to tell fread() which values should be treated as missing values.
You will be importing the following file:
id,name,val1,val2
9002019291929192,Robert Whitaker,,44
9200129401349301 ,Elisa Waters,289,##
9200149429834456 , Karla Schmidt,458,29
The missing values are encoded as "##". Note that fread() handles an empty field ,, by default as NA.
This exercise is part of the course
Data Manipulation with data.table in R
Exercise instructions
Import the file sample.csv properly to ensure that "##" is treated as a missing values and is imported as NA.
Hands-on interactive exercise
Have a go at this exercise by completing this sample code.
# Import the file using na.strings
missing_values <- ___
missing_values