[GitHub] [arrow-cookbook] nealrichardson commented on a change in pull request #41: [R] Remove unnecessary head()s

[GitBox <gi...@apache.org>]

nealrichardson commented on a change in pull request #41:
URL: https://github.com/apache/arrow-cookbook/pull/41#discussion_r692179176



##########
File path: r/content/reading_and_writing_data.Rmd
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@@ -60,11 +60,11 @@ Given a Parquet file, it can be read back in by using `arrow::read_parquet()`.
 
 ```{r, read_parquet}
 parquet_tbl <- read_parquet("my_table.parquet")
-head(parquet_tbl)
+parquet_tbl
 ```
 ```{r, test_read_parquet, opts.label = "test"}
 test_that("read_parquet works as expected", {
-  expect_equivalent(dplyr::collect(parquet_tbl), tibble::tibble(group = c("A", "B", "C"), score = c(99, 97, 99)))
+  expect_identical(as.data.frame(parquet_tbl), tibble::tibble(group = c("A", "B", "C"), score = c(99, 97, 99)))

Review comment:
       That's not what I see locally:
   
   ```
   > my_table <- Table$create(tibble::tibble(group = c("A", "B", "C"), score = c(99, 97, 99)))
   > write_parquet(my_table, "my_table.parquet")
   > attributes(read_parquet("my_table.parquet"))
   $names
   [1] "group" "score"
   
   $class
   [1] "tbl_df"     "tbl"        "data.frame"
   
   $row.names
   [1] 1 2 3
   
   > attributes(tibble::tibble(group = c("A", "B", "C"), score = c(99, 97, 99)))
   $names
   [1] "group" "score"
   
   $row.names
   [1] 1 2 3
   
   $class
   [1] "tbl_df"     "tbl"        "data.frame"
   ```
   
   I see that the attributes are in a different order, which while not functionally relevant, could mean that they don't test equally. We just got a JIRA about this this week, in fact.
   
   Note that `collect` just wraps `as.data.frame()`: https://github.com/apache/arrow/blob/master/r/R/dplyr-collect.R#L43-L49
   
   Side note: if the cookbook tests were to use testthat 3rd edition, we'd get better diffs of what attributes don't match.
   




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