[R] Unexpected result for df column $ subset with non-existent name

[Rui Barradas]

Às 14:52 de 28/10/2022, Sergei Ko escreveu:
> Hi All,
> 
> Just noticed that R returns results for non-existent name if you have
> another variable with the same beginning when you subset with $.
> See the code below:
> name_0 <- "ID"
> name_1 <- "name"
> name_2 <- "name1"
> 
> v0 <- 1:200
> v1 <- c(rep(0,100), rep(1,100))
> v2 <- c(rep(0,50), rep(1,150))
> 
> df <- as.data.frame(cbind(v0, v1, v2))
> colnames(df) <- c(name_0, name_1, name_2)
> 
> df_1 <- df[, c(name_0, name_1)]
> df_2 <- df[, c(name_0, name_2)]
> 
> table(df$name)
> table(df_1$name)
> table(df_2$name)
> colnames(df_2)[2] <- "name10"
> table(df_2$name)
> colnames(df_2)[2] <- "name_any"
> table(df_2$name)
> table(df_2[,"name"])
> 
> The last row produces an error as intended.
> Any ideas?
> 
> Win 10
> R version 4.2.1 (2022-06-23 ucrt) -- "Funny-Looking Kid"
> 
> Regards,
> Sergiy
> 
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> 
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Hello,

This behavior, partial matching of column or list members names when 
extracting with `$` is practically a FAQ.
See the latest R-Help thread on it after the release of R 4.0


https://stat.ethz.ch/pipermail/r-help/2020-May/467143.html


Hope this helps,

Rui Barradas