Python Script

Description

The script block Python Script can run external Python functions, from .py files, so you can develop your own algorithms.

Preqequisite

Python 3.6 or above must be installed.

Input

The input is MxN and your function will be receiving a dictionary as seen below. You can manipulate the keys of the dictionary but the variable type of each key should remain constant.

import numpy as np

data = {'0': {'msg': '',

'fs': np.array([[48000]]),

'xlabel': np.array([['Time']]),

'ylabel': np.array([['Amplitude']]),

'xunit': np.array([['s']]),

'yunit': np.array([['SPL']]),

'X': np.array([[1],

[2],

[3]]),

'Y': np.array([[5],

[8],

[9]])

}

}

Output

The output is KxL and is the return dictionary from you Python function. An example of some python processing can be seen below.

def bar(data, variables):

"""

Example function to be used in a SAFE processing block

:param data: A dictionary of all the incoming datasets

:param variables: A dictionary of all the variables your have defined in the current project

:return: data, variables: The data dictionary and the variables dictionary

"""

data['0']['Y'] = data['0']['Y'] * 2

variables['my_var'] = 4

return data, variables

if __name__ == '__main__':

import sys

import json

import numpy as np

import time

def serializeDict(d):

return {k.replace('\'', '"'): v.tolist() if isinstance(v, np.ndarray) else serializeDict(v) if isinstance(v, dict) else v for k, v in d.items()}

def deserializeDict(d):

return {k.replace('\'', '"'): np.array(v) if isinstance(v, list) else deserializeDict(v) if isinstance(v, dict) else v for k, v in d.items()}

info, variables = {}, {}

for i, arg in enumerate(sys.argv):

if i == 2:

variables = deserializeDict(json.loads(arg)) # decode data to numpy arrays

data = deserializeDict(json.loads(sys.stdin.read())) # read and decode data to numpy arrays

# If you need to setup something before running the function do it here

returnList = list(globals()[sys.argv[1]](data, variables)) # function call

for ret in returnList[:2]:

if not isinstance(ret, dict):

raise ValueError('Function must return two dictionaries.')

print(json.dumps(serializeDict(ret))) # encode and print output

# NO PRINTS AFTER THIS LINE #

Attributes

Attribute	Value
Name	Python Script
File Path
Function Name	foo
Timeout (seconds)	5
Channels	1

Name

Name specifies the name of the block.

File Path

The filepath is the path to the Python .py file you want to use.

Function Name

The function name is the name of the function you want to run inside your Python script.

Timeout (seconds)

The timeout parameter determines how long time SAFE will wait for the script to execute.

Channels

Channels specifies the number of input(s)/output(s) the block will have.

Literature

• Python
• Download Python for Windows