In Grapher 13 and newer versions, true classed Piper plots and unclassed Piper plots were added as built-in graph types, so plotting your data is easier than ever! Follow the steps in the article Create a Piper Plot (Trilinear Diagram) in Grapher if you have Grapher 13 or newer.
A sample Piper plot created in Grapher 12.
A sample plot and data file are attached (G12 - PiperPlot.zip). A second sample file uses colored symbols as labels is also attached (G12 - PiperColor.zip). In addition, a Piper plot sample is contained in the Samples directory for Grapher 12.
Both data files display ID, cations, anions, and two combined columns. The anions in columns E, F, and G (highlighted in blue below) should be normalized to add up to 100%. The cations in column B, C, and D (highlighted in red below) should be normalized to add up to 100%. After the columns are normalized the worksheet can be used to create the Piper plot. Columns I and J (highlighted in green below) use a formula to create combined data. The grapher colors.xlsx file contains color names and a symbol in column K. Columns L and M are used to label the cation bottom left ternary diagram.
Verify that the cations and anions add to 100 before creating the Piper plot.
Using different symbols in a Piper plot is typical to show different collection areas or to demonstrate differences in total dissolved solids among the samples. To create a classed piper plot in Grapher 12 and earlier versions, complete the steps below.
- Download the attached zip file containing the template files (G11 - PiperPlot.zip).
- Edit the piper plot example worksheet to contain your data. This can be done in Grapher by completing the steps below. Alternatively, the changes can be made directly in Excel.
- Unzip the file to extract the GRF Grapher file and the XLSX data file. The data file displays class name, cations, anions, and two combined columns. The cations and anions should all be normalized to add up to 100%. Additionally there are three extra columns at the end of the file for custom axes labels.
- Open Grapher and click Open Document in the Welcome dialog.
- In the Open dialog, navigate to the XLSX data file, select it, and click Open. The data file opens in Grapher’s worksheet.
- Replace the data in Cols B-G with your own normalized cation and anion concentrations.
- Click Cells | Data | Transform. Change First row to 2 and then type Transform equation: I=G+F. Click OK.
The Transform dialog showing the transform used to calculate the x component for the diamond plot.
- Go to Cells | Data | Transform. Change First row to 2 and then type Transform equation: J=B-sin(D2R(30))*I. Click OK.
The Transform dialog showing the transform used to calculate the y component for the diamond plot.
Note that the D2R here is important because it converts the 30 (degrees) to radians.
- Use File | Save to save the data file to the same name, or File | Save As to save to your own name.
- Once the data has been entered into the worksheet, complete the steps below to create the piper plot.
- Click File | Open.
- In the Open dialog navigate to the GRF file that came in the ZIP file you downloaded earlier. Select it and click Open.
- If you saved your data to a new name, click on Class Scatter Plot 1 under Piper Points in the Object Manager.
- In the Plot tab of the Property Manager, change the Worksheet to your new data file.
- Repeat steps 11 and 12 for Ternary Class Plot 1 under Right Class Ternary and Left Class Ternary.
Now you have a Piper plot of your own data using custom symbol classes. In just a few short minutes you’ve plotted a visually-appealing, completely customizable Piper plot which will wow your audience and quickly inform them of what the groundwater has to offer.
Updated July 15, 2019