Find row based on its value

Question

I remember coming across this issue in the past but I cannot find the solution anymore.

For a dataframe with the numeric column a I want to find the row for which a = 27.99. View the dataframe I know that in row 100 this is the case.

So:

> df$a[100]
27.99

> df$a[100] == 27.99
FALSE

> which(df$a == 27.99)
integer(0)

> is.numeric(df$a[100])
TRUE

I remember it might have to do with machine precision.

should not happen with integer data actually. Can you add a reproducible example? Moreover, you can check with `which(sapply(df$a, all.equal, 28) == TRUE)` — Ronak Shah, Mar 22 '19 at 09:12
Oh, yes, maybe I should specify, it's not an integer but rather `27.99`. I'll edit the post. — Pascal, Mar 22 '19 at 09:13

score 0 · Accepted Answer · answered Mar 22 '19 at 09:15

0

Could be an issue with floating points, try:

which(round(df$a) == 28)

answered Mar 22 '19 at 09:15

MatthewR

1 Answers1