Question

I do I remove all rows in a dataframe where a certain row meets a string match criteria?

For example:

A,B,C
4,3,Foo
2,3,Bar
7,5,Zap

How would I return a dataframe that excludes all rows where C = Foo:

A,B,C
2,3,Bar
7,5,Zap

Answer 1

Just use the == with the negation symbol (!). If dtfm is the name of your data.frame:

dtfm[!dtfm$C == "Foo", ]

Or, to move the negation in the comparison:

dtfm[dtfm$C != "Foo", ]

Or, even shorter using subset():

subset(dtfm, C!="Foo")