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Lazy eval, dplyr "filter" and NAs

I have some silly problem using lazy evaluation and dplyr. I'm trying to filter out some NA

and don't know why the lazyeval version is not working. I guess I missed something, but I can't find it. Is this true, or is this a bug?

Here's a minimal reproducible example:

library(dplyr)
library(lazyeval)

data(iris)
iris$t <- c(1:140, rep(NA, 10))

#This Works
temp <- filter(iris, !is.na(t))

#This doesn't
temp <- filter_(iris, interp(~(!is.na(x)), x="t"))

Both codes run without throwing an error.

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2 answers


You need to pass "t"

as a name.

interp(~(!is.na(x)), x = as.name("t"))
# ~!is.na(t)


When your code stands, you paste "t"

in is.na()

to make is.na("t")

it FALSE every time. And the negation that gives TRUE every time, hence all rows.

interp(~(!is.na(x)), x = "t")
# ~!is.na("t")
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dplyr switched its NSE system from lazyeval to rlang (documented here ), deprecating functions *_

in favor of the new syntax:



library(dplyr)

data(iris)
iris <- iris %>% mutate(t = c(1, rep(NA, 149)))

# normal NSE
iris %>% filter(!is.na(t))
#>   Sepal.Length Sepal.Width Petal.Length Petal.Width Species t
#> 1          5.1         3.5          1.4         0.2  setosa 1

# string-based SE; use `rlang::sym` to convert to quosure and !! to unquote
x <- "t"
iris %>% filter(!is.na(!!rlang::sym(x)))
#>   Sepal.Length Sepal.Width Petal.Length Petal.Width Species t
#> 1          5.1         3.5          1.4         0.2  setosa 1

# program your own NSE with `quo` and friends
x <- quo(t)
iris %>% filter(!is.na(!!x))
#>   Sepal.Length Sepal.Width Petal.Length Petal.Width Species t
#> 1          5.1         3.5          1.4         0.2  setosa 1

# both versions work across the tidyverse
iris %>% tidyr::drop_na(!!x)
#>   Sepal.Length Sepal.Width Petal.Length Petal.Width Species t
#> 1          5.1         3.5          1.4         0.2  setosa 1

# though tidyr::drop_na is happy with strings anyway
iris %>% tidyr::drop_na("t")
#>   Sepal.Length Sepal.Width Petal.Length Petal.Width Species t
#> 1          5.1         3.5          1.4         0.2  setosa 1
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