I want to draw a line through some of my data points and get the equation in Grapher. Can I?

Yes! Grapher has the ability to create a fit curve, limit it to an X range of data, and get the equation. To do so: 
  1. Click on the Line/Scatter Plot 1 object in the Object Manager.
  2. In the Property Manager, click on the Plot tab.
  3. Click the Add/Edit button next to the Fit curve command.
  4. In the Fits dialog,
    1. Select Linear, Y=B*X+A from the Available Fits list.
    2. Click Add.
    3. Click OK.
    The fit curve is added. By default, it fits all of the data. 
  5. Click on the Fit 1: Linear object in the Object Manager.
  6. In the Property Manager, click on the Plot tab.
  7. In the Fitted Plot section, uncheck the box next to Apply fit to entire plot.
  8. Update the Minimum plot value to fit and Maximum plot value to fit with the x values for the range of data you would like to use. For example, if you want to limit the equation to the red area on this graph, type in 40900 for Minimum plot value to fit and 40945 for the Maximum plot value to fit.

After changing the fit curve Fitted Plot properties, your fit curve will be reduced to the area in red.

  1. To get the equation of the line:
    1. Click the Fit 1: Linear plot.
    2. In the Property Manager, click on the Plot tab. 
    3. In the Statistics section, click the button next to one of the commands.
      • Clicking on the Copy button next to the Copy to clipboard command copies the information to the Windows clipboard for pasting into Grapher or another program.
      • Clicking on the Display button next to the Display report command opens a text window in Grapher with the fit curve information.
      • Clicking on the Insert button next to the Insert into plot document  command allows you to click in the plot document window and have the fit curve information displayed as an editable text object.


Updated January 12, 2018

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