Hi,

When using the `sum`

function (and probably other similar functions), the `na.rm`

argument has a weird characteristic that if all the observations are `NA`

s it will return 0. For example:

```
> x <- c(NA, NA, NA)
> sum(x, na.rm = TRUE)
[1] 0
```

As I am interested that the function will return NA if and only if all the observations are NAs by using the following condition:

```
> sum(x, na.rm = any(!is.na(x)))
[1] NA
```

Any suggestion on how to apply this condition when using `dplyr::summarise_all`

? For example, here is the function I am using:

```
df1 <- df %>% dplyr::select(-TIMESTAMP) %>%
dplyr::group_by(date, hour) %>%
dplyr::summarise_all(list(base::sum), na.rm = ???)
```

Thanks,

Rami