带有下拉菜单的 Altair 条形图 - 选择和不选择时保持条形宽度相同

Question

I am trying to create a chart in Altair with dropdowns. Here's the code

df = pd.DataFrame([["Merc","US",500, "Car_A"], ["BMW","US" ,55, "Car_B"]
                   , ["BMW","US",40, "Car_C"], ["Merc", "China",650, "Car_D"]
                  , ["BMW","US",80, "Car_E"], ["Merc", "China",850, "Car_F"]], columns=list("ABCD"))

position_dropdown_Type = alt.binding_select(name = "Type:" , options=[None] + list(df["B"].unique()), labels = ['All'] + list(df["B"].unique()))
position_selection_Type = alt.selection_single(fields=['B'], bind=position_dropdown_Type)

position_dropdown_1_Car = alt.binding_select(name = "Company:", options=[None] + list(df["A"].unique()), labels = ['All'] + list(df["A"].unique()))
position_selection_1_Car = alt.selection_single(fields=['A'], bind=position_dropdown_1_Car, name = "__")

#interval = alt.selection_multi(fields=['GICS_SUB_IND'], bind='legend')
Car_bar=alt.Chart(df).mark_bar().encode(
            color = 'A',   
            y = alt.Y('C', scale=alt.Scale(domain=[0, 1.2*df["C"].max()]),
                      title = 'Range'),
            x = alt.X('D:O', sort = alt.EncodingSortField(field="C", order='ascending', op='max'), title = 'Care_Name')
             ).add_selection(interval).add_selection(position_selection_Type).transform_filter(position_selection_Type).add_selection(position_selection_1_Car).transform_filter(position_selection_1_Car)

(Car_bar).properties(width = 700)

the code works with a graph like this when all values are selected

However, when I make a selection, the bar width takes the entire width as seen below

Defining size inside mark_bar(size = 10) is not an option as the code will be accessing different datasets with wide range of sample size. Also, since the dropdown list will be quite long, selecting from the legend is also not ideal.

Is there a way to keep the width same for the bars with the selection from dropdown?

Answer 1

It seem the issue is with the properties(width = 700) setting. It is forcing the bar width to be large enough to satisfy the width setting. If you remove that, it will give adapt the bar width accordingly.