Line plots

Plot live and past channel data, zoom and measure it, and set up the plot.

A line plot graphs the values of channels over time. It shows live data as it arrives, or the data of past ranges. Use a line plot to watch a test, to compare runs, and to measure and export data.

Create a line plot

1. Click in the tab bar, or press Ctrl+T (Cmd+T on macOS).
2. Select Line plot.
3. Press V to open the component toolbar.
4. On the Data tab, select one or more channels in Y1.

The plot shows the last 30 seconds of data and adds each new sample when it arrives. If a range is active, the plot shows that range instead.

You can also run the “Create line plot” command from the command palette. In the channels toolbar, double-click a channel to add it to the focused line plot, or to a new line plot when none is focused.

Choose a time range

The Ranges field on the Data tab sets the time that the plot shows. Select one or more items:

• A rolling span, such as Rolling 30s or Rolling 1h, shows live data. The plot moves as new samples arrive.
• Custom sets your own rolling span. Enter a duration such as 1h 30m.
• A range shows the data of that range. The list holds your favorite ranges and the ranges that you added to plots. To add a range to the list, favorite it.

To plot a range from the ranges toolbar, right-click the range and select Add to new plot. To add it to the focused line plot, select Add to active plot.

Each range keeps its real times, so two runs on different days sit apart on the x-axis.

The plot marks each range in Synnax that overlaps the visible time as a shaded band with its name. Right-click a band to select View details, Open in new plot, or Download as CSV. To hide the bands, click in the top right of the plot.

Add channels to the plot

On the Data tab:

• Y1 plots channels against the left axis.
• Y2 plots channels against the right axis. Use it for channels with a different unit, such as temperature next to pressure.
• X1 sets the channel of the x-axis. Leave it empty to plot against time.

You can also drag a channel from the channels toolbar onto an axis of the plot.

The axis lists do not show virtual, string, json, or uuid channels. To see text values, use a log.

Zoom, pan, and pause

The buttons in the top right of the plot set what a drag does: Zoom (), Pan (), or Select (). Zoom is the default.

On macOS, use Cmd for Ctrl and Option for Alt. Press Esc to cancel a drag. To reset the zoom, you can also click .

To stop a live plot from moving, click or press H. Click or press H again to resume. When you resume, the plot resets its zoom.

To show the time and the value of each line under the cursor, turn on Show tooltip on hover (). It is on by default.

How the plot loads data

A line plot does not draw each sample of a long time range. It loads groups of samples that fit the width of the plot. The Aggregation and Detail of each line set how the plot draws the groups. See lines.

• Zoom in -> the plot loads finer data for the new view. The coarse data stays on the plot until the finer data arrives.
• Pan past the time range -> the plot loads the data there. To go back to the time range, click or Ctrl+click the plot.
• First load -> while the plot loads a range, or a rolling span longer than one minute, it shows a message such as Fetching 1h of data.

Select a region

1. Hold Alt (Option on macOS) and drag across the plot.
2. Right-click the selection.
3. Select an action:
   • Copy ISO time range, Copy Python time range, or Copy TypeScript time range copies the start and end of the selection.
   • Create range from selection opens the create range dialog with the times of the selection. See create ranges.
   • Download region as CSV downloads the data of the selection. See export data.

To download the data of the whole plot, click in the component toolbar.

Measure between two points

1. Click (Open measure tool) in the top right of the plot.
2. Click a point on a line. Then click a second point.

The plot shows the difference in time (ΔX), the difference in value (ΔY), and the slope between the two points. Each point snaps to the nearest sample. To move a point, press 1 or 2, then click a new position. Pause a live plot first, so the points stay in place.

Add a rule

A rule is a horizontal line at a fixed value, such as a pressure limit. The Rules tab calls rules “annotations”.

1. Open the component toolbar and select the Rules tab.
2. Click Add annotation.
3. Set the label, the value, the axis, and the color.

To move a rule, drag it on the plot.

Use the legend

The legend lists each line with its color and label.

• Click the eye beside a line to hide or show it.
• Click a color swatch to change the color of the line.
• Click a label to rename the line. The channel keeps its name.
• Drag the legend to move it.

Toolbar reference

Open the component toolbar with V, or double-click the plot. The header has buttons to download the data as CSV, export the plot, and copy a link to it.

Data

Lines

Each line has one row. The fields have tooltips, not labels.

Aggregation shows only for a line whose X1 is time or an index channel. A line whose X1 is a different channel draws the first sample of each group.

Axes

Properties

Rules

Troubleshooting

The plot is empty

Cause

The time range has no data for the channels.

Fix

• The range has no samples -> make sure that Ranges has a rolling span or a range in which the channels have samples.
• No live data arrives -> check that a task or a script writes to the channels.

A range is not in the Ranges list

Cause

The list holds only your favorite ranges and ranges that you added to plots.

Fix

Favorite the range, or right-click it in the ranges toolbar and select Add to active plot.

A channel is not in the Y1 list

Cause

The axis lists hide virtual, string, json, and uuid channels.

Fix

Use a log for text values.

The toolbar says the plot is not editable

Cause

You do not have permission to change the plot. You can still zoom, pan, and select.

Fix

Ask an administrator for access.

H does not pause the plot

Cause

H needs permission to change the plot.

Fix

Click instead.