Subsetting in R

[James, Cassandra]

Hi All,

 

A small R conundrum that I am sure I should be able to solve but always seem to get stuck when it comes to subsetting data based on information in another column of the same dataframe.

 

I have two columns of data (HydroID and NextDownID). I want to identify all the values for HydroID that DONT occur in NextDownID.

 

(basically this is to identify all the river network heads to start an accumulation of runoff downstream).

 

Any help appreciated!

 

Thanks

 

Cassie

[Phillips, Ben]

Hey Cassie,

You need the within operator: %in%


B

Excuse the brevity: sent from my phone.

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[stewartmacdonald]

I'm guessing that my last message was also flagged as spam, so I'll try posting this from the website.

Does this work?

HydroID <- c(1, 2, 3, 4, 5, 6)

NextDownID <- c(5, 6, 7, 8, 9, 10)

df <- data.frame(HydroID, NextDownID)

df$HydroID[!(df$HydroID %in% df$NextDownID)]

Stewart

[Stewart Macdonald]

Does this work?


HydroID <- c(1, 2, 3, 4, 5, 6)
NextDownID <- c(5, 6, 7, 8, 9, 10)
df <- data.frame(HydroID, NextDownID)

df$HydroID[!(df$HydroID %in% df$NextDownID)]


Stewart