Percentage rather than counts

I’m trying to create a bar plot aggregating the data points into percentages. So I would like to do something like

plot = alt.Chart(data).mark_bar().encode(
    x = "CategoricalVariable",
    y = "count(*)/sum(count(*))")
)

but for the past hours I’ve completely failed to find a way of how to do that.

[jakevdp]

Oh, turns out it has already been updated: https://github.com/altair-viz/altair/blob/3541d9531974e6d9d0772e84bc662b96b78f5a2c/altair/examples/percentage_of_total.py#L14-L16

[jakevdp]

It looks like you want something like this (not tested):

alt.Chart(
    allLikelihoods
 ).transform_joinaggregate(
    groupby = ['phi'], phiLikelihood = 'sum(logLikelihood)'
 ).transform_calculate(
    logPhi = 'exp(datum.phiLikelihood)'
).transform_joinaggregate(
    totalLikelihod = 'sum(logPhi)'
).transform_calculate(
   logTotalLikelihood = 'log(totalLikelihood)'
)