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Python can be used to both create diagrams using the GraphViz system.

The default extension of a GraphViz file usually either dot or gv.

Note: You may need to install GraphViz for your system. See the following.

• Graphviz: dot (non-Python install)
• GraphViz: expression trees (non-Python usage)

There are several Python packages to support GraphViz.

The more simple Python graphviz package will be used here. The web site is https://pypi.org/project/graphviz/ (as of 2020-04-06). One way to install the graphviz package is as follows.

Use the path to your installed version of Python. The feedback while installing should look something like the following (as of 2020-04-06).

Here is the Python code.
import os from PIL import Image from graphviz import Digraph basePs1 = "./" saveFn1 = "dot21-1-01" saveFt1 = "png" saveFs0 = "{0:s}{1:s}".format(basePs1,saveFn1) saveFs1 = "{0:s}{1:s}.{2:s}".format(basePs1,saveFn1,saveFt1) dot1 = Digraph(comment="Input Process Output",format=saveFt1) dot1.graph_attr["rankdir"] = "LR" dot1.node("input1","Input") dot1.node("process1","Process") dot1.node("output1","Output") dot1.edge("input1","process1") dot1.edge("process1","output1") # Quirk: render will add the file extension dot1.render(saveFs0) savedImage1 = Image.open(saveFs1) savedWidth1, savedHeight1= savedImage1.size (_, _, _, _, _, _, savedSize1, _, savedTime1, _) = os.stat(saveFs1) print("Dot image:") print("") print("\t{0:s} : {1:d} x {2:d} , {3:,} bytes".format(saveFs1,savedWidth1,savedHeight1,savedSize1)) print("") print("Dot source:") print("") print("{0:s}".format(dot1.source))
Here is the output of the Python code.
Dot image: ./dot21-1-01.png : 391 x 59 , 8,308 bytes Dot source: // Input Process Output digraph { graph [rankdir=LR] input1 [label=Input] process1 [label=Process] output1 [label=Output] input1 -> process1 process1 -> output1 }