Diagram with only days on the x-axis and reduce function problem

I have created an aggregation function that uses a reduce function to count activations (0-1 transitions of a device) per day. This already works nearly as I would like it to. The only thing missing is, that when the day is changed, and the device is already active during change of day, I don’t want to count the activation.

The next missing piece is that when I want to show the graph, I only see a dot for each sum, no line is printed. Is there a way to setup a bar chart? At least a connection between the measurements would be fine.

Here’s the query

from(bucket: "myBucket")
  |> range(start: v.timeRangeStart, stop: v.timeRangeStop)
  |> filter(fn: (r) => r["_measurement"] == "heating")
  |> filter(fn: (r) => r["_field"] == "Verdichter")
  |> window(every: 1d)
  |> reduce(
      fn: (r, accumulator) => ({
          sum: if accumulator.lastval == 0 and r._value == 1 then 
                accumulator.sum + 1
            else accumulator.sum,
          lastval: r._value
      identity: {sum: 0, lastval: 0.0},
  |> duplicate(column: "_start", as: "_time")
  |> duplicate(column: "sum", as: "_value")
  |> yield(name: "_value")

I’m completely new to InfluxDB, so I appreciate your help!

Thank you