geo.ST_LineString() function
The geo.ST_LineString() function is experimental and subject to change at any time.
By using this function, you accept the risks of experimental functions.
The geo.ST_LineString() function converts a series of geographic points into
linestring.
Group data into meaningful, ordered paths to before converting to linestring.
Rows in each table must have lat and lon columns.
Output tables contain a single row with a st_linestring column containing the resulting linestring.
geo.ST_LineString() is an aggregate function.
import "experimental/geo"
geo.ST_LineString()
Examples
Convert a series of geographic points into linestring
Input data
| _time | id | lon | lat |
|---|---|---|---|
| 2020-01-01T00:00:00Z | a213b | 39.7515 | 14.01433 |
| 2020-01-02T00:00:00Z | a213b | 38.3527 | 13.9228 |
| 2020-01-03T00:00:00Z | a213b | 36.9978 | 15.08433 |
import "experimental/geo"
data
|> geo.ST_LineString()
Output data
| id | st_linestring |
|---|---|
| a213b | 39.7515 14.01433, 38.3527 13.9228, 36.9978 15.08433 |
Function definition
ST_LineString = (tables=<-) =>
tables
|> reduce(fn: (r, accumulator) => ({
__linestring: accumulator.__linestring + (if accumulator.__count > 0 then ", " else "") + string(v: r.lat) + " " + string(v: r.lon),
__count: accumulator.__count + 1
}), identity: {
__linestring: "",
__count: 0
}
)
|> rename(columns: {__linestring: "st_linestring"})
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