[jira] [Updated] (ARROW-6583) [Rust] Question and Request for Examples of Array Operations

["Neville Dipale (Jira)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/ARROW-6583?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Neville Dipale updated ARROW-6583:
----------------------------------
    Fix Version/s:     (was: 1.0.0)

> [Rust] Question and Request for Examples of Array Operations
> ------------------------------------------------------------
>
>                 Key: ARROW-6583
>                 URL: https://issues.apache.org/jira/browse/ARROW-6583
>             Project: Apache Arrow
>          Issue Type: Improvement
>          Components: Rust
>            Reporter: [DELETED]
>            Priority: Minor
>
> Hi all, thank you for your excellent work on Arrow.
> As I was going through the example for the Rust Arrow implementation, specifically the read_csv example [https://github.com/apache/arrow/blob/master/rust/arrow/examples/read_csv.rs] , as well as the generated Rustdocs, and unit tests, it was not quite clear what the intended usage is for operations such as filtering and masking over Arrays.
> One particular use-case I'm interested in is finding all values in an Array such that x >= N for all x. I came across arrow::compute::array_ops::filter, which seems to be similar to what I want, although it's expecting a mask to already be constructed before performing the filter operation, and it was not obviously visible in the documentation, leading me to believe this might not be idiomatic usage.
> More generally, is the expectation for Arrays on the Rust side that they are just simple data abstractions, without exposing higher-order methods such as filtering/masking? Is the intent to leave that to users? If I missed some piece of documentation, please let me know. For my use-case I ended up trying something like:
> {code:java}
> let column = batch.column(0).as_any().downcast_ref::<Float64Array>().unwrap();
> let mut builder = BooleanBuilder::new(batch.num_rows());
> let N = 5.0;
> for i in 0..batch.num_rows() {
>    if column.value(i).unwrap() > N {
>       builder.append_value(true).unwrap();
>    } else {
>       builder.append_value(false).unwrap();
>    }
> }
> let mask = builder.finish();
> let filtered_column = filter(column, mask);{code}
> If possible, could you provide examples of intended usage of Arrays? Thank you!
>  
>  



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