[R] subset data frame problem

[Kai Yang]

 Thans Richard, it works well. --- Kai
    On Monday, December 13, 2021, 04:00:33 AM PST, Richard O'Keefe <raoknz using gmail.com> wrote:  
 
 You want to DELETE rows satisfying the condition P & Q.The subset() function requires an expression saying whatyou 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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