问题
I'm trying to produce something similar to the K-top example.
Except that instead of filtering out and displaying the same aggregated field data, I want:
- to display one type of aggregated data (the max of daily temps)
- and filter on another aggregation field ( the mean of daily temps)
I've created an observable notebook here to build my test case, and this is how far I got.
{
"$schema": "https://vega.github.io/schema/vega-lite/v4.json",
"data": {"url": "data/seattle-weather.csv"},
"transform": [
{"timeUnit": "month", "field": "date", "as": "month_date"},
{
"joinaggregate": [
{"op": "mean", "field": "precipitation", "as": "mean_precipitation"},
{"op": "max", "field": "precipitation", "as": "max_precipitation"}
],
"groupby": ["month_date"]
},
{
"aggregate": [
{"as": "aggregation", "field": "precipitation", "op": "mean"}
],
"groupby": ["month_date"]
},
{"window": [{"op": "row_number", "as": "rank"}]},
{"calculate": "datum.rank <= 100? datum.month_date : null", "as": "dates"},
{"filter": "datum.dates != null"}
],
"encoding": {
"x": {"field": "dates", "type": "ordinal", "timeUnit": "month"}
},
"layer": [
{
"mark": {"type": "bar"},
"encoding": {
"y": {
"aggregate": "max",
"field": "precipitation",
"type": "quantitative"
}
}
},
{
"mark": "tick",
"encoding": {
"y": {
"aggregate": "mean",
"field": "precipitation",
"type": "quantitative"
},
"color": {"value": "red"},
"size": {"value": 15}
}
}
]
}
I feel I'm missing something link the GroupBy.ngroup
from pandas.DataFrame
回答1:
You can do this following Vega-Lite's Filtering Top-K Items example along with an extra aggregate transform. Here is an example adapting your spec from above (vega editor):
{
"$schema": "https://vega.github.io/schema/vega-lite/v4.json",
"title": "Top Months by Mean Precipitation",
"data": {"url": "data/seattle-weather.csv"},
"transform": [
{"timeUnit": "month", "field": "date", "as": "month_date"},
{
"aggregate": [
{"op": "mean", "field": "precipitation", "as": "mean_precipitation"},
{"op": "max", "field": "precipitation", "as": "max_precipitation"}
],
"groupby": ["month_date"]
},
{
"window": [{"op": "row_number", "as": "rank"}],
"sort": [{"field": "mean_precipitation", "order": "descending"}]
},
{"filter": "datum.rank < 10"}
],
"encoding": {
"x": {
"field": "month_date",
"type": "ordinal",
"timeUnit": "month",
"title": "month (descending by max precip)",
"sort": {
"field": "max_precipitation",
"op": "average",
"order": "descending"
}
}
},
"layer": [
{
"mark": {"type": "bar"},
"encoding": {
"y": {
"field": "mean_precipitation",
"type": "quantitative",
"title": "precipitation (mean & max)"
}
}
},
{
"mark": "tick",
"encoding": {
"y": {"field": "max_precipitation", "type": "quantitative"},
"color": {"value": "red"},
"size": {"value": 15}
}
}
]
}
来源:https://stackoverflow.com/questions/60151507/filtering-an-aggregated-chart-with-another-aggregation-field