[R] why data frame's logical index isnt working

[Michael Artz]

I don't get it, I thought the double index was to indicate and individual
element within a column(vector)?
I will stop using data.frame, thanks a lot!

On Thu, Apr 7, 2016 at 9:29 PM, David Winsemius <dwinsemius at comcast.net>
wrote:

>
> > On Apr 7, 2016, at 6:46 PM, Michael Artz <michaeleartz at gmail.com> wrote:
> >
> > data.frame.$columnToAdd["CurrentColumnName" == "ConditionMet"] <- 1
> >
> > Can someone please explain to me why the above command gives all NAs to
> > columnToAdd?  I thought this was possible in R to do logical expression
> in
> > the index of a data frame
>
> It is possible, but please execute this at a console line and then read
> ?"[" to see what is happening:
>
> "CurrentColumnName" == "ConditionMet"  # almost surely FALSE
>
> Let's assume your dataframe were named 'dat'.
>
> Perhaps you meant to write:
>
> dat$colToAdd[ dat[["CurrentColumnName"]] == dat[["ConditionMet"]] ] <- 1
>
> And do please stop naming your dataframes "data.frame".
>
>
> >
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> >
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>
> David Winsemius
> Alameda, CA, USA
>
>

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