By: David Anthoff

Re-posted from: https://www.queryverse.org//2018/08/29/query-v0.10/

I just released Query.jl v0.10. This is the first version that is compatible with julia 1.0, and at the same time it drops support for older julia versions.

This version comes with two breaking changes, other than that there are no new features.

New way to select group key

In previous versions one selected the value of a group key via the .key syntax, like in this example:

@from i in df begin
    @group i by i.children into g
    @select {Key=g.key,Count=length(g)}
    @collect DataFrame
end

This syntax is no longer support, instead you have to use the key function to access the key of a group:

@from i in df begin
    @group i by i.children into g
    @select {Key=key(g),Count=length(g)}
    @collect DataFrame
end

.. syntax removed

In previous versions one could use the a..b syntax as a shortcut for map(i->i.b, a). This syntax has been removed, and instead groups of table rows now support access to a whole column via a simple a.b syntax. For example, a typical groupby query might now look like this:

@from i in df begin
    @group i by i.state into g
    @select {group=key(g),mage=mean(g.age), oldest=maximum(g.age), youngest=minimum(g.age)}
    @collect DataFrame
end