Deleting rows dataframe in R conditional to “if any of (a specific variable) is equal to”

Question

I have been struggling for some time now with this code... I have this vector of unique ID "EID" of length 821 extracted from one of my dataframe (skate). It looks like this:

> head(skate$EID)
[1] "896-19" "895-8"  "899-1"  "899-5"  "899-8"  "895-7" 

I would like to remove the complete rows in another dataframe (t5) if any of the t5$EID is equal (a duplicate) of skate$EID.

I was able to get my 'duplicated' dataframe in t5 of all my matching EID as follow:

> xx<-skate$EID
> t5[match(xx,t5[,26]), ]#gives me a dataframe of all matching EID in skate$EID
       record.t trip set month stratum NAFO unit.area time dur.set distance
8948          5  896  19    11     221   2J       N12  908      15        8
8849          5  895   8    10     766   3O       R36 1650      16        8
9289          5  899   1    12     743   3L       V26 2052      15        8
9299          5  899   5    12     746   3L       W27 1129      14        7

Where t5[,26] correspond to t5$EID column. I'm sure it's simple, but I'm not sure how to remove all of these now from my t5 dataframe! Tips would be very much appreciated! Thank you!

Answer 1

There are many ways to do this. To test for elements of vector A not in vector B, you can use a combination of ! , R's logical negation operator (see ?"!" ) and %in% (see ?%in% ). You then use the results of that test to indicate which rows to keep.

# Create two example data.frames
skate <- data.frame(EID = c("896-19", "895-8", "899-1", "899-5"), 
                    score = 1:4)
t5 <- data.frame(EID = c("896-19", "camel", "899-1", "goat", "899-1"), 
                 score = 105:101)

# Method 1
t5[!t5$EID %in% skate$EID, ] 

# Method 2 (using the very handy subset() function)
subset(t5, !EID %in% skate$EID)