You can use the radio_button_tag
helper and set the checked
parameter correctly.
Using your example, it's something like this:
.form-group.pull-left
= label_tag :metric, 'Metric', class: 'sr-only'
.btn-group{"data-toggle" => "buttons"}
%label.btn.btn-default.active
= radio_button_tag('options', 'value1', params[:options] == 'value1')
Value1
%label.btn.btn-default
= radio_button_tag('options', 'value2', params[:options] == 'value2')
Value2