Use Ramda indexBy with variable index - functional-programming

Question

I need to transform some JSON data, and Ramda's indexBy does just about exactly what I want. The code below works for a single object:
const operativeIndex = R.pipe(R.head, R.keysIn,
R.intersection(['Weight', 'Height', 'Month', 'Week']), R.head);
const reIndex = R.indexBy(R.prop(operativeIndex(testObject)), testObject);
But to map an array of objects through my re-indexing function, I believe I need to rewrite reIndex so that it needs only a single injection of testObject.
How can I do that?
To help visualize the task: the current code transforms testObject from an array like this, which will have one of the 4 allowed indices:
[{ Height: '45',
L: '-0.3521',
M: '2.441',
S: '0.09182'},
{ Height: '45.5',
L: '-0.3521',
M: '2.5244',
S: '0.09153'}]
into an object like this:
{ '45':
{ Height: '45',
L: '-0.3521',
M: '2.441',
S: '0.09182' },
'45.5':
{ Height: '45.5',
L: '-0.3521',
M: '2.5244',
S: '0.09153' } }

Answer 1

If I understand your question correctly you want reIndex to be a function that takes a list of objects and produces an object index.
If yes you could do it this way
const operativeIndex = R.pipe(
R.keysIn,
R.intersection(['Weight', 'Height', 'Month', 'Week']),
R.head
)
const reIndex = R.indexBy(R.chain(R.prop, operativeIndex))
Then you could do reIndex(list) Demo.
BTW keep in mind that keysIn goes up the prototype chain and the order is NOT guaranteed.