Question

I have a JSON file with parsed data stored in a @colors instance variable, as follows:

[{:color=>"red", :value=>"#f00"} {:color=>"green", :value=>"#0f0"} {:color=>"blue", :value=>"#00f"} {:color=>"cyan", :value=>"#0ff"} {:color=>"magenta", :value=>"#f0f"} {:color=>"yellow", :value=>"#ff0"} {:color=>"black", :value=>"#000"}]

Now I want to iterate through this output to create a table in a view where there is

<tr><td>color</td><td>value</td></tr>

When I derive another instance variable like this —

@even_colors = @colors.values_at(* @colors.each_index.select {|i| i.even?}).map(&:values)

I get an array of arrays consisting of every other color/value pair

[["red", "#f00"], ["blue", "#00f"], ["magenta", "#f0f"], ["black", "#000"]]

But what I want to create two separate arrays, one consisting only of the color names indicated by :color (red, blue, etc.) and the other consisting of just the hexs indicated by :value (#f00, #00f, etc.). I can’t seem to figure out how to do that. Anyone have any suggestions? Thanks …

Answer 1

You could do it with two passes through @colors:

names = @colors.map { |h| h[:color] }
hexes = @colors.map { |h| h[:value] }

Or you could it with on pass:

parts = @colors.each_with_object({ :names => [ ], :hexes => [ ]}) do |h, parts|
    parts[:names].push(h[:color])
    parts[:hexes].push(h[:value])
end

then look at parts[:names] for the color names and parts[:hexes] for the hex values.

I don’t really see why you want to split @colors up though, you could produce your table straight from@colors:

<table>
    <% @colors.each do |h| %>
        <tr><td><%= h[:color] %></td><td><%= h[:value] %></td></tr>
    <% end %>
</table>

Breaking @colors into two arrays seems like busy-work to me.