Sascha created ARROW-7028:
-----------------------------
Summary: Dates in R are different when saved and loaded with
parquet
Key: ARROW-7028
URL: https://issues.apache.org/jira/browse/ARROW-7028
Project: Apache Arrow
Issue Type: Bug
Components: R
Affects Versions: 0.15.0
Reporter: Sascha
When saving R-dataframes with parquet and loading them again, the internal
representation of Dates changes, leading e.g. to errors when comparing them in
dplyr::if_else.
``` r
library(dplyr)
#>
#> Attaching package: 'dplyr'
#> The following objects are masked from 'package:stats':
#>
#> filter, lag
#> The following objects are masked from 'package:base':
#>
#> intersect, setdiff, setequal, union
tmp = tempdir()
dat = tibble(tag = as.Date("2018-01-01"))
dat2 = tibble(tag2 = as.Date("2019-01-01"))
arrow::write_parquet(dat, file.path(tmp, "dat.parquet"))
dat = arrow::read_parquet(file.path(tmp, "dat.parquet"))
typeof(dat$tag)
#> [1] "integer"
typeof(dat2$tag2)
#> [1] "double"
bind_cols(dat, dat2) %>%
mutate(comparison = if_else(TRUE, tag, tag2))
#> `false` must be a `Date` object, not a `Date` object
```
<sup>Created on 2019-10-30 by the [reprex
package](https://reprex.tidyverse.org) (v0.3.0)</sup>
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