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