[GitHub] [arrow-rs] alamb opened a new issue #519: Allow creation of StringArrays from Vec

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

alamb opened a new issue #519:
URL: https://github.com/apache/arrow-rs/issues/519


   **Is your feature request related to a problem or challenge? Please describe what you are trying to do.**
   The usecase is I have a Vec of derived `String` values but I can not create a StringArray from them
   
   **Describe the solution you'd like**
   I would like to be able to run:
   ```rust
   let my_array = StringArray::from(v);
   ```
   
   For any `v` that has things that can be borrowed as `str` or `Option<str>` (including `String` and others) rather than only `str`).
   
   It looks like there is some attempt to be able to do this already: https://github.com/apache/arrow-rs/blob/master/arrow/src/array/array_string.rs#L208 but it isn't clear to me why it doesn't work
   
   **Additional context**
   Here is an example
   
   ```rust
   
   fn main() {
       // I want to make a StringArray from a derived type
       let my_data = vec!["Foo", "Bar", "Baz"];
       let my_derived_data = my_data.iter()
           .map(|s| format!("Some transformed data"))
           .collect::<Vec<_>>();
   
       let a = StringArray::from(my_data); // works!
       assert_eq!(a.len(), 3);
   
       // however, if I want to to create a StringArray from an array of Strings, that is no good
       //let b = StringArray::from(my_derived_data); // <----- does not work!
       //assert_eq!(b.len(), 3);
   
   //    |
   // 14 |     let b = StringArray::from(my_derived_data); // does not work!
   //    |             ^^^^^^^^^^^^^^^^^ the trait `From<Vec<String>>` is not implemented for `GenericStringArray<i32>`
   //    |
   //    = help: the following implementations were found:
   //              <GenericStringArray<OffsetSize> as From<ArrayData>>
   //              <GenericStringArray<OffsetSize> as From<Vec<&str>>>
   //              <GenericStringArray<OffsetSize> as From<Vec<Option<&str>>>>
   //              <GenericStringArray<T> as From<GenericListArray<T>>>
   //    = note: required by `from`
   }
   ```


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[GitHub] [arrow-rs] alamb closed issue #519: Allow creation of StringArrays from Vec

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

alamb closed issue #519:
URL: https://github.com/apache/arrow-rs/issues/519


   


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