[R] subset data frame problem

[Richard O'Keefe]

You want to DELETE rows satisfying the condition P & Q.
The subset() function requires an expression saying what
you want to RETAIN, so you need subset(PD, !(P & Q)).

test <- subset(PD, !(Class == "1st" & Survived == "No"))

By de Morgan's laws, !(P & Q) is the same as (!P) | (!Q)
so you could also write

test <- subset(PD, Class != "1st" | Survived != "No")

I'd actually be tempted to do this in two steps:

unwanted <- PD$Class == "1st" & PD$Survived == "No"
test <- PD[!unwanted,]




On Mon, 13 Dec 2021 at 17:30, Kai Yang via R-help <r-help using r-project.org>
wrote:

> Hi R team,I want to delete records from a data frame if Class = '1st' and
> Survived = 'No'. I wrote the code below, test <- subset(PD, Class != '1st'
> && Survived != 'No')
> but the code return a wrong result. Can someone help me for this?
> Thanks,Kai
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