Strangeness with filtering in R and showing summary of filtered data

Question

I have a data frame loaded using the CSV Library in R, like

mySheet <- read.csv(\"Table.csv\", sep=\";\")

I now can print a summary on that

Answer 1

What you are dealing with here are factors from reading the csv file. You can get subSheet to forget the missing factors with

subSheet$Diagnose <- droplevels(subSheet$Diagnose)

or

subSheet$Diagnose <- subSheet$Diagnose[ , drop=TRUE] 

just before you do summary(subSheet).

Personally I dislike factors, as they cause me too many problems, and I only convert strings to factors when I really need to. So I would have started with something like

mySheet <- read.csv("Table.csv", sep=";", stringsAsFactors=FALSE)