在 R dataframe 中查找值的单元格引用

Question

I am trying to find a way to search within a dataframe to return the column and row reference for multiple conditions.

#some data 
SalesData<-data.frame(Appliance=c("Radio", "Laptop", "TV", "Fridge"), ThisYear=c(5,25,5,8), LastYear=c(6,20,5,8))

 #code to find which row column TV is in which correctly gives row 3, col 1
 TVRef<-which(SalesData==("TV"), arr.ind=TRUE)

In the SalesData dataframe I would want to search for the dataframe (row, column) reference where Appliance = TV and where LastYear = 5.

I know how to search for a single item in R as per the above code but I don't know how to do this for multiple items. For this example I would want to return the result row 3, col 3 so I could then reuse this in further code to update the dataframe.

Is there anything anyone can suggest?

Answer 1

You can use a logical and ( & ) and pass multiple condition to row selector as follows:

SalesData[c(SalesData$Appliance=="TV" & SalesData$LastYear==5),][[3]]
#[1] 5

An alternative using with can be done follows:

with(SalesData, SalesData[Appliance=="TV" & LastYear==5,][[3]])
#[1] 5

This is a numeric output which you can do

SalesData[c(SalesData$Appliance=="TV" & SalesData$LastYear==5),][[3]] <- 500
# To replace it with say 500. 

Answer 2

I like using dplyr functions that make it read pretty easily

SalesData<-data.frame(Appliance=c("Radio", "Laptop", "TV", "Fridge"), ThisYear=c(5,25,5,8), LastYear=c(6,20,5,8))


library(dplyr)


SalesData %>% 
  filter(Appliance == "TV" & LastYear == 5)