[Rd] mydataframe$colname: using substring of colname may also match some column (PR#7496)

From: <marc_at_intershop.de>
Date: Wed 12 Jan 2005 - 21:50:50 EST


Full_Name: Marc Mamin
Version: 1.8, 2.0.0
OS: Windows & Linux
Submission from: (NULL) (217.17.202.254)

Using only the beginning of a column name will match it:

>aaa<-1
>df<-as.data.frame(aaa)
>names(df)

[1] "aaa"

>df$a

[1] 1 !!!!!!!!! (I expect df$a to be undefind)

>df$x
>NULL
Compare with:

> df["aaa"]

  aaa
1 1

> df["a"]

Error in "[.data.frame"(df, "a") : undefined columns selected

Here another example that underline how problematic this issue can be:

aa1<-1
aa2<-2
df<-as.data.frame(aa1,aa2)
> df$aa

[1] 1 (only the first matching column is retrieved)



R-devel@stat.math.ethz.ch mailing list
https://stat.ethz.ch/mailman/listinfo/r-devel Received on Wed Jan 12 20:56:27 2005

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