Basic pie (ram*location)

general.scale = { percent: { formatter: val => (val * 100).toFixed(2) + '%'}}
coord.type = 'theta'  

stack.enabled = true
stack.type = 'percent'
stack.as = 'percent'  
stack.field = 'ram'
stack.dimension = 'location'   
 
geometry.types = ['intervalStack']  
geometry.positions = ['percent']  
geometry.color = 'location'

label.content = 'percent'

legend.positions = 'bottom'
legend.title = false

Nightingale Rose pie (model*location)

coord.type = 'polar'
stack.enabled = false  
 
geometry.types = ['interval']  
geometry.position = ['model', 'location']  
geometry.color = 'location'

label.content = ''

Empty circle inside of pie aka Ring-pie

coord.radius = 1.0
coord.innerRadius = .6