Question: Is there no way to create a DictionaryArray with a pre-arranged mapping?

[jmrgibson]

It would appear from the docs that you cannot create a DictionaryArray by defining both the keys and and values? This is opposed to the python API which does. This is quite useful for cases where the dictionary mapping is defined elsewhere (e.g., a C enum). Are there plans to add this? Or am I reading the docs wrong. Thanks!

[jhorstmann]

There is StringDictionaryBuilder::new_with_dictionary which allows specifying existing dictionary values when building an array.

There is also a low-level way of building array from an underlying ArrayData struct, but this is much more complex than the python api you pointed too. So I agree, such an api would be quite useful.

[jmrgibson]

Ah neat, yeah new_with_dictionary is what I wanted, I was just looking in the wrong place. Thanks!

[jhorstmann]

For combining keys with an existing dictionary there is also PrimitiveBuilder::finish_dict. This is not that obvious to find in the documentation and I also forgot about it.