Flowcharts in Graphviz

Flowcharts are great but WYSIWYG flowcharting software is horrible. Fortunately, there us Graphviz. This free tool allows for the creation of network diagrams, including flowcharts, using The Dot Language. We'll use the pydot python library, though there are other choices. Start by installing graphviz. Use conda to install pydot by typing

> conda install pydot

into the shell (Linux/OSX) or the Anaconda shell (Windows). Then you are ready to create nodes, connect them with edges, and build a typical flowchart.

A notebook is available with the code below. Download and open in jupyter.

# imports
import os
import pydot
from IPython.display import Image, display
# setup
ng = pydot.Dot(graph_type='digraph')
# nodes
startN = pydot.Node("start", style="filled", fillcolor="yellow")
stopN = pydot.Node("stop", style="filled", fillcolor="red")
# modifiers
makeChartN = pydot.Node("make\nchart", shape="box")
dullChartN = pydot.Node("remove\ndetail", shape="box")
noiseChartN = pydot.Node("add\nnoise", shape="box")
# tests
infoCapN = pydot.Node("useful items\n >? N + random", shape="diamond")
noiseFloorN = pydot.Node("distractions\n <? N + random", shape="diamond")
# collection
nodeL = [startN, makeChartN, dullChartN, noiseChartN, infoCapN, noiseFloorN, stopN]
# add nodes to chart
for nodeN in nodeL:
    ng.add_node(nodeN)
# add edges
ng.add_edge(pydot.Edge(startN, makeChartN))
ng.add_edge(pydot.Edge(makeChartN, infoCapN))
 
ng.add_edge(pydot.Edge(infoCapN, dullChartN, label="Y"))
ng.add_edge(pydot.Edge(infoCapN, noiseFloorN, label="N"))
 
ng.add_edge(pydot.Edge(dullChartN, noiseFloorN))
 
ng.add_edge(pydot.Edge(noiseFloorN, noiseChartN, label="Y"))
ng.add_edge(pydot.Edge(noiseFloorN, stopN, label="N"))
 
ng.add_edge(pydot.Edge(noiseChartN, infoCapN))
# display
ng.write_png("typicalFlowchart.png")
Image("typicalFlowchart.png")