# How to create one line plot per color series in Observable Plot? **URL:** \ **Category:** Help\ **Created:** [February 7, 2022, 11:22am UTC](https://talk.observablehq.com/t/how-to-create-one-line-plot-per-color-series-in-observable-plot/6174 "2022-02-07T11:22:30Z")\ **Posts on this page:** 6\ **Page:** 1
**Author:** ![NeonMika](https://yyz2.discourse-cdn.com/flex030/user_avatar/talk.observablehq.com/neonmika/32/6105_2.png) [@NeonMika](https://talk.observablehq.com/u/NeonMika)\ **Post date:** [February 7, 2022, 11:22am UTC](https://talk.observablehq.com/t/how-to-create-one-line-plot-per-color-series-in-observable-plot/6174/1 "2022-02-07T11:22:30Z")
**Cross-posting from [javascript - How to create one line plot per color series in Observable Plot? - Stack Overflow](https://stackoverflow.com/q/71017484/2938364).** * * * **Description:** I am playing around with Observable Plot an really like how easy it is to set up simple plots. Now I have a little “more advanced” chart that I want to plot and need help. In my data, I have multiple `temp` (temperature) readings recorded at a certain `timestamp`. Each reading comes from a `sensor`, and each `sensor` is attached to a certain `device` (multiple sensors (e.g., 1-3) can be attached to a single device (e.g., 2)). Thus, one data point might look like the following (see bottom script for a full minimal workabel example): ```auto { timestamp: 1, device: 1, sensor: 1, temp: 20 } ``` Currently, I _dot plot_ this data, _facet_ it based on the sensor, and give a color the each `(device, sensor)` pair series (just see below snippet or run it on Stack Overflow to get a better feeling). **Problem:** I now would like to connect all dots of the same color with a black line. I marked the problematic line with `// HERE I NEED HELP` in the snippet. I assume that I somehow have to group `data` based on `device` and `sensor` to achieve a similar grouping to the color, but I sadly have no idea how to achieve this and hope that you can help! ```auto Home Automation

Home Automation

``` Thank you! ---
**Author:** ![Fil](https://yyz2.discourse-cdn.com/flex030/user_avatar/talk.observablehq.com/fil/32/207_2.png) [@Fil](https://talk.observablehq.com/u/Fil)\ **Post date:** [February 7, 2022, 11:30am UTC](https://talk.observablehq.com/t/how-to-create-one-line-plot-per-color-series-in-observable-plot/6174/2 "2022-02-07T11:30:18Z")
I think what you want is ```auto z: (d) => `Sensor ${d.sensor} of device ${d.device}`, ``` (answer also cross-posted 😉 ) ---
**Author:** ![NeonMika](https://yyz2.discourse-cdn.com/flex030/user_avatar/talk.observablehq.com/neonmika/32/6105_2.png) [@NeonMika](https://talk.observablehq.com/u/NeonMika)\ **Post date:** [February 7, 2022, 11:53am UTC](https://talk.observablehq.com/t/how-to-create-one-line-plot-per-color-series-in-observable-plot/6174/3 "2022-02-07T11:53:16Z")
Hello Fil, thank you very much! Do you have any link where I can learn more about `z`? Thanks! ---
**Author:** ![Fil](https://yyz2.discourse-cdn.com/flex030/user_avatar/talk.observablehq.com/fil/32/207_2.png) [@Fil](https://talk.observablehq.com/u/Fil)\ **Post date:** [February 7, 2022, 12:00pm UTC](https://talk.observablehq.com/t/how-to-create-one-line-plot-per-color-series-in-observable-plot/6174/4 "2022-02-07T12:00:27Z")
It’s documented in [https://github.com/observablehq/plot#area](https://github.com/observablehq/plot#area) and [https://github.com/observablehq/plot#line](https://github.com/observablehq/plot#line) _z_ is used to separate series; it defaults to _stroke_ or _fill_ when then are channels, which is why most of the time you don’t need to specify it explicitly. ---
**Author:** ![NeonMika](https://yyz2.discourse-cdn.com/flex030/user_avatar/talk.observablehq.com/neonmika/32/6105_2.png) [@NeonMika](https://talk.observablehq.com/u/NeonMika)\ **Post date:** [February 7, 2022, 1:00pm UTC](https://talk.observablehq.com/t/how-to-create-one-line-plot-per-color-series-in-observable-plot/6174/5 "2022-02-07T13:00:42Z")
Oh, now I feel stupid seeing it so clearly in the API documentation. Thanks again! ---
**Author:** ![Fil](https://yyz2.discourse-cdn.com/flex030/user_avatar/talk.observablehq.com/fil/32/207_2.png) [@Fil](https://talk.observablehq.com/u/Fil)\ **Post date:** [February 7, 2022, 5:29pm UTC](https://talk.observablehq.com/t/how-to-create-one-line-plot-per-color-series-in-observable-plot/6174/6 "2022-02-07T17:29:59Z")
No reason to feel bad, it’s a lot to process!