PyFlowchart

PyFlowchart is a package to:

• write flowchart in Python,
• translate Python source codes into flowchart.

PyFlowchart produces flowcharts in flowchart.js flowchart DSL, a widely used flow chart textual representation. It's easy to convert these flowcharts text into a picture via flowchart.js.org, francoislaberge/diagrams, or some markdown editors.

Get PyFlowchart

$ pip3 install pyflowchart

Flowchart in Python

PyFlowchart including flowchart.js node types:

• StartNode
• OperationNode
• ConditionNode
• InputOutputNode
• SubroutineNode
• EndNode

Nodes can be connected by connect() method (connect_{yes|no} for ConditionNode).

Get a Flowchart with your start node and call its flowchart() method to generate flowchart.js flowchart DSL：

from pyflowchart import *

st = StartNode('a_pyflow_test')
op = OperationNode('do something')
cond = ConditionNode('Yes or No?')
io = InputOutputNode(InputOutputNode.OUTPUT, 'something...')
sub = SubroutineNode('A Subroutine')
e = EndNode('a_pyflow_test')

# define the direction the connection will leave the node from
sub.set_connect_direction("right")
    
st.connect(op)
op.connect(cond)
cond.connect_yes(io)
cond.connect_no(sub)
sub.connect(op)
io.connect(e)
 
fc = Flowchart(st)
print(fc.flowchart())

Output:

st4471442960=>start: start a_pyflow_test
op4471442064=>operation: do something
cond4471501392=>condition: Yes or No?
io4471501648=>inputoutput: output: something...
e4471501904=>end: end a_pyflow_test
sub4471501584=>subroutine: A Subroutine

st4471442960->op4471442064
op4471442064->cond4471501392
cond4471501392(yes)->io4471501648
io4471501648->e4471501904
cond4471501392(no)->sub4471501584
sub4471501584(right)->op4471442064

Go http://flowchart.js.org and translate the generated textual representation into SVG flow chart diagrams:

P.S. Many Markdown editors (for example, Typora) support this flowchart syntax, too. And if you prefer CLI, see francoislaberge/diagrams.

Python to Flowchart

PyFlowchart can also translate your Python Codes into Flowcharts.

For example, you got a simple.py:

def foo(a, b):
    if a:
        print("a")
    else:
        for i in range(3):
            print("b")
    return a + b

Run PyFlowchart in CLI to generate flowchart code:

$ python3 -m pyflowchart simple.py

# output flowchart code.

Or, in Python

>>> from pyflowchart import Flowchart
>>> with open('simple.py') as f:
...     code = f.read()
... 
>>> fc = Flowchart.from_code(code)
>>> print(fc.flowchart())

# output flowchart code.

Advanced Usages

As mentioned above, we use Flowchart.from_code to translate Python code into Flowchart. The from_code is defined as:

Flowchart.from_code(code, field='', inner=True, simplify=True)

PyFlowchart CLI is a 1:1 interface for this function:

python3 -m pyflowchart [-f FIELD] [-i] [--no-simplify] code_file

Let's talk about those three args:

• field: Specify a field of code to generate flowchart
• inner: True: parse the body of field; Field: parse the body as a object
• simplify: for If & Loop statements: simplify the one-line-body or not

field

field is the path to a field (i.e. a function) you want to draw flowchart.

# example.py
print("start")

def foo():
    foo = "foo"

class Bar():
    def buzz(self, f):
        def g(self):
            print("g")
            f(self)
        return g(self)

Bar().buzz(foo)
print("end")

For example.py above, available paths are:

- "" (means the whole code)
- "foo"
- "Bar.buzz"
- "Bar.buzz.g"

To generate a flowchart of Bar.buzz.g：

# Python
from pyflowchart import Flowchart
with open('example.py') as f:
	code = f.read()
fc = Flowchart.from_code(code, field='Bar.buzz.g', inner=False)
print(fc.flowchart())

# CLI
python3 -m pyflowchart example.py -f Bar.buzz.g

Output result:

inner

inner controls parser's behaves. Techly, inner=True means parsing field.body, while inner=False parses [field]. So, if inner=True, pyflowchart will look into the field, otherwise it takes field as a node.

For CLI, adding an argument -i means inner=True, else inner=False.

simplify

simplify is for If & Loop statements: simplify the one-line-body.

For example:

# example_simplify.py
a = 1
if a == 1:
    print(a)
while a < 4:
    a = a + 1

• Default: simplify=True:

flowchart = Flowchart.from_code(example_simplify_py, field="", inner=True)
print(flowchart.flowchart())
# CLI $ p3 -m pyflowchart example_simplify.py 

• simplify=False:

flowchart = Flowchart.from_code(example_simplify_py, field="", inner=True, simplify=False)
print(flowchart.flowchart())
# CLI $ p3 -m pyflowchart --no-simplify example_simplify.py 

Beautify Flowcharts

Modify the generated flowchart code by yourself.

TODO

• Generate flowchart SVG/HTML.

$ pyflowchart example.py -o flowchart.svg

Depends node.js and flowchart.js.

• PyFlowchart GUI

Well, I guess a GUI for PyFlowchart may be remarkable. Pasting your code into it, the flowchart DSL will be generated just in time, and flowchart will be shown aside.

• The Chinese README your buddies waiting for!

Sadly, I am too busy (this word is pronounced as [ˈlеizi]——lazy) to code these ideas. Please submit an issue to push me on. Or, PR to make it by yourself. I cannot wait to appreciate your great contribution!

References

• Inspired by Vatsha/code_to_flowchart
• Based on adrai/flowchart.js, python ast, simonpercivall/astunparse
• A blog about this project

License

Copyright 2020 CDFMLR. All rights reserved.

Licensed under the MIT License.