Transformers

Transformer Interface

class zircon.transformers.base.BaseTransformer

Abstract base class defining the Transformer interface.

A Transformer takes in messages, applies some transformation, and spits them back out. It is a general piece of middleware in a data stream that can be used to compress/decompress, encode/decode, or split/combine messages in a data pipeline.

Usage:

def process(msg):
    do_something(msg)

t = MyTransformer()
t.set_callback(process)

for msg in messages:
    t.push(msg)

set_callback(callback)

Set a function to be invoked for each outputted message.

push(msg)

Feed in a message.

Pass-through Transformer

class zircon.transformers.base.Transformer

Bases: zircon.transformers.base.BaseTransformer

Transformer that acts as a pass-through, invoking the callback for each message received with no alterations.

Extend this and override push() to implement a Transformer.

set_callback(callback)

output(msg)

If I have a callback, invoke it.

push(msg)

Output exactly what I receive.

Common Transformers

class zircon.transformers.common.Combiner(limit)

Bases: zircon.transformers.base.Transformer

Combine messages into a list, then send them out.

__init__(limit)

Parameters:limit – How many messages to combine.

push(msg)

class zircon.transformers.common.Doubler

Bases: zircon.transformers.base.Transformer

Output each message twice.

push(msg)

class zircon.transformers.common.Splitter

Bases: zircon.transformers.base.Transformer

Split messages into parts by iterating through them.

push(msg)

class zircon.transformers.common.Uppercaser

Bases: zircon.transformers.base.Transformer

Capitalize string-like messages.

push(msg)

class zircon.transformers.common.Lowercaser

Bases: zircon.transformers.base.Transformer

Lowercase string-like messages.

push(msg)

class zircon.transformers.common.Pickler

Bases: zircon.transformers.base.Transformer

Pickle messages with the latest protocol.

push(msg)

class zircon.transformers.common.Unpickler

Bases: zircon.transformers.base.Transformer

Unpickle messages with the latest protocol.

push(msg)

class zircon.transformers.common.Compressor

Bases: zircon.transformers.base.Transformer

Compress messages using zlib.

push(msg)

class zircon.transformers.common.Decompressor

Bases: zircon.transformers.base.Transformer

Decompress messages using zlib.

push(compressed_msg)

class zircon.transformers.common.TimedCombiner(dt=0.1)

Bases: zircon.transformers.base.Transformer

Convert individual data points into a dictionary of signal names to time series, outputted at a regular interval.

Input: (12345, ‘MYSIGNAL’, -5.2), (12346, ‘MYSIGNAL’, 1.3), ... Output: {‘MYSIGNAL’: ((12345, -5.2), (12346, 1.3))}

__init__(dt=0.1)

push(msg)

class zircon.transformers.common.Printer(prefix=None)

Bases: zircon.transformers.base.Transformer

Prints messages and passes them on unaltered.

__init__(prefix=None)

push(msg)

class zircon.transformers.common.Timer

Bases: zircon.transformers.base.Transformer

Prints the time between messages, and passes them on unaltered.

__init__()

push(msg)