Hi,

How do you subset a dataframe so that you only have columns:

1.       that contain one or more NAs?

2.       that contain factors with greater than or equal to 32 levels?

How do you remove from a dataframe columns**

3.       with one or more NA's?

4.       that contain factors with greater than or equal to 32 levels?

** I know how to remove columns at a basic level but I am trying to figure out a more efficient way of performing these particular tasks (my data set has 60 columns).
For NA's I essentially used summary(mtcars) and manually made a note of where NA's appeared than used:
mtcars1<-mtcars1[,!(names(mtcars1)%in% c("hp","wt","vs"))]
I did something similar for factors with greater than x levels only I used str(mtcars) to help me identify them.
BTW I know mtcars doesn't have any of these issues. I just used it as a quick reference.


Dan


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