Sorting
Edit this page{
"data": ... ,
"mark": ... ,
"encoding": {
"x": {
"field": ...,
"type": ...,
"sort": ..., // sort
...
},
"y": ...,
...
},
...
}
The sort
property of a mark properties channel determines the order of the scale domain. Supported sort
values depend on the field’s scale type.
Sorting Continuous Scales
If the channel has a continuous scale (quantitative or time), sort
can have the following values:

"ascending"
(Default) – the field is sorted by the field’s value in ascending order. 
"descending"
– the field is sorted by the field’s value in descending order.
Example: Reversed XScale
Setting x’s sort
to "descending"
reverses the xaxis. Thus, the following visualization’s xaxis starts on the maximum value of the field “Horsepower” and ends on zero.
Sorting Discrete Scales
If the channel has a discrete scale (band
, point
or ordinal
), the field’s values of the channel can be sorted in the following ways:
1) Sorting by the values’ natural order in Javascript. For example, "a"
< "b"
. In this case, sort
can be:

"ascending"
(Default) – sort by the field’s value in ascending order. 
"descending"
– sort by the field’s value in descending order.
2) Sorting by aggregated value of another “sort” field. In this case, sort
is a sort field definition object, which has the following properties:
Property  Type  Description 

field  String  RepeatRef 
The data field to sort by. Default value: If unspecified, defaults to the field specified in the outer data reference. 
op  AggregateOp 
Required. An aggregate operation to perform on the field prior to sorting (e.g., For a full list of operations, please see the documentation for aggregate. 
order  String 
The sort order. One of 
3) Unsorted – null
– The field is not sorted. This is equivalent to specifying sort: false
in Vega’s scales.
4) Specify custom order by providing custom scale
’s domain
. (In this case, you don’t need to use sort
property.)
Example: Sorting Ordinal Scale by Another Field
The following example sorts x by mean of Horsepower.