[R] Odd behavior of a function within apply

[Andrew Simmons]

When you use apply, it converts the input to an array, so all of the
integer columns in your data frame are converted to character class. I
would use lapply, sapply, or vapply instead to do this, I think you just
need to remove the "MARGIN" argument.

On Mon, Aug 8, 2022, 13:25 Erin Hodgess <erinm.hodgess using gmail.com> wrote:

> Hello!
>
> I have the following data.frame
>  dput(test1.df[1:10,8:10])
> structure(list(X1_1_HZP1 = c(48160L, 48198L, 80027L, 48161L,
> NA, 48911L, NA, 48197L, 48021L, 11355L), X1_1_HBM1_mon = c("December",
> "June", "August", "", "", "August", "April", "February", "",
> "December"), X1_1_HBM1_yr = c(2014L, 2018L, 2016L, NA, NA, 1985L,
> 2019L, 1993L, NA, 1990L)), row.names = c(NA, 10L), class = "data.frame")
>
> And the following function:
> > dput(count1a)
> function (x)
> {
>     if (typeof(x) == "integer")
>         y <- sum(is.na(x))
>     if (typeof(x) == "character")
>         y <- sum(x == "")
>     return(y)
> }
> When I use the apply function with count1a, I get the following:
>  apply(test1.df[1:10,8:10],2,count1a)
>     X1_1_HZP1 X1_1_HBM1_mon  X1_1_HBM1_yr
>            NA             3            NA
> However, when I do use columns 8 and 10, I get the correct response:
>  apply(test1.df[1:10,c(8,10)],2,count1a)
>    X1_1_HZP1 X1_1_HBM1_yr
>            2            3
> >
> I am really baffled.  If I use count1a on a single column, it works fine.
>
> Any suggestions much appreciated.
> Thanks,
> Sincerely,
> Erin
>
>
> Erin Hodgess, PhD
> mailto: erinm.hodgess using gmail.com
>
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>
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