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# python-compton
An abstract data-flow framework for quantitative trading, which decouples data initialization, data composition and data processing.
## Install
```sh
pip install compton
```
## Usage
```py
from compton import (
Orchestrator,
Provider,
Reducer,
Consumer
)
```
## Vector
We call a tuple of hashable parameters as a vector which is used to identify a certain kind of data.
```py
from enum import Enum
class DataType(Enum):
KLINE = 1
ORDER_BOOK = 2
class TimeSpan(Enum):
DAY = 1
WEEK = 2
vector = (DataType.KLINE, TimeSpan.DAY)
```
## Orchestrator(reducers, loop=None)
- **reducers** `List[Reducer]` reducers to compose data
- **loop?** `Optional[EventLoop]` The event loop object to use. In most cases, you should **NOT** pass this argument, unless you exact know what you are doing.
```py
Orchestrator(
reducers
).connect(
provider
).subscribe(
consumer
).add('TSLA')
```
### orchestrator.connect(provider: Provider) -> self
Connects to a data provider
### orchestrator.subscribe(consumer: Consumer) -> self
Subscribes the consumer to orchestrator.
### orchestrator.add(symbol: str) -> self
Adds a new symbol to orchestrator, and start the data flow for `symbol`
## Provider
`Provider` is an abstract class which provides initial data and data updates.
A provider should be implemented to support many symbols
We must inherit class `Provider` and implement some abstract method before use.
- `@property vector` returns an `Vector`
- `async def init()` method returns the initial data
- There is an protected method `self.dispatch(symbol, payload)` to set the payload updated, which should only be called in a coroutine, or a `RuntimeError` is raised.
```py
class MyProvider(Provider):
@property
def vector(self):
return (DataType.KLINE, TimeSpan.DAY)
async def init(self, symbol):
return {}
```
## Reducer
Another abstract class which handles data composition.
The `reducer.vector` could be a generic vector which applies partial match to other vectors
```py
class MyReducer(Reducer):
@property
def vector(self):
# So, MyReducer support both
# - (DataType.KLINE, TimeSpan.DAY)
# - and (DataType.KLINE, TimeSpan.WEEK)
return (DataType.KLINE,)
def merge(self, old, new):
# `old` might be `None`, if `new` is the initial data
if old is None:
# We could clean the initial data
return clean(new)
return {**old, **new}
```
## Consumer
A consumer could subscribes to more than one kind of data types
```py
class MyConsumer(Consumer):
@property
def vectors(self):
# Subscribe to two kinds of data types
return [
(DataType.KLINE, TimeSpan.DAY),
(DataType.KLINE, TimeSpan.WEEK)
]
@property
def all(self) -> bool:
"""
`True` indicates that the consumer will only go processing
if both of the data corresponds with the two vectors have changes
And by default, `Consumer::all` is False
"""
return True
@property
def concurrency(self) -> int:
"""
Concurrency limit for method `process()`
By default, `Consumer::concurrency` is `0` which means no limit
"""
return 1
def should_process(self, *payloads) -> bool:
"""
If this method returns `False`, then the data update will not be processed
"""
return True
# Then there will be
# both `kline_day` and `kline_week` passed into method `process`
async def process(self, symbol, kline_day, kline_week):
await doSomething(symbol, kline_day, kline_week)
```
## License
[MIT](LICENSE)