title: Error in vapply ... values must be length 1, but FUN(X[[11]]) result is length 0
body: <p>I've never been very skilled with R and am coming back after an absence so I'm re-learning a lot. I've got a dataset (named data) that has fields latitude and longitude. Some of the observations have '0' in these fields, which is invalid data. I'm writing an R notebook to document my findings.</p>
  
  <p>I have:</p>
  
  <pre><code>    Let's start by finding out how many records have 0 for latitude and longitude. If it's a great deal of records, we might not be able to rely on these fields:
  ```{r}
  nrow(filter(data, latitude == 0.0))
  nrow(filter(data, longitude == 0.0))
  ```
  Okay, there are 12 rows that have 0 for latitude and 12 rows that have 0 for longitude. I'm willing to bet these are the same rows. Let's find out.
  
  ```{r}
  filter(data, latitude == 0.0)
  ```
  </code></pre>
  
  <p>The first two lines that start with nrow() both display the output I expect:</p>
  
  <pre><code>[1] 12
  [1] 12
  </code></pre>
  
  <p>However, the same filter statement, which I expect to output the 12 rows that match the filter criteria, gives me an error when I run the chunk:</p>
  
  <pre><code>Error in vapply(x, obj_sum, character(1L)) : values must be length 1,
   but FUN(X[[11]]) result is length 0
  </code></pre>
  
  <p>I don't understand why I'm getting this error. The 'data' variable is a tibble, if that makes a difference.</p>
  
  <p>I'd sure appreciate an explanation of what's happening here.</p>