Dominic Dennenmoser created ARROW-8813:
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Summary: Implementing tidyr interface
Key: ARROW-8813
URL: https://issues.apache.org/jira/browse/ARROW-8813
Project: Apache Arrow
Issue Type: Improvement
Components: R
Reporter: Dominic Dennenmoser
I think it would be reasonable to implement an interface to the {{tidyr}}
package. The implementation would allow to lazily process ArrowTables before
put it back into the memory. However, currently you need to collect the table
first before applying tidyr methods. The following code chunk shows an example
routine:
{code:r}
library(magrittr)
arrow_table <- arrow::read_feather("table.feather", as_data_frame = FALSE)
nested_df <-
arrow_table %>%
dplyr::select(ID, 4:7, Value) %>%
dplyr::filter(Value >= 5) %>%
dplyr::group_by(ID) %>%
dplyr::collect() %>%
tidyr::nest(){code}
The main focus might be the following three methods:
* {{tidyr::[un]nest()}},
* {{tidyr::pivot_[longer|wider]()}}, and
* {{tidyr::seperate()}}.
I suppose the last two can be fairly quickly implemented, but {{tidyr::nest()}}
and {{tidyr::unnest()}} cannot be implement before conversion to List<Struct>
will be accessible.
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