Jhonathan Abreu
f2100adb46
* Test * Fix price shift on continuous future rollover * Keep track of both data and exchange time in subscription data reader * Fix for daily and hourly resolutions. Add daily and hour algorithms * Fixes for emitting new exchange dates at the beginning and end when data is not available * Cleanup * Minor fix * Minor fix: detect mapping in data reader after advancing time keeper * Minor fix * More fixes * More fixes * Fixes for universe files * More fixes for daily resolution data * Separate DateChangeTimeKeeper to its own file * Add DateChangeTimeKeeper unit tests * Minor fix * Add more DateChangeTimeKeeper unit tests * Address peer review * Address peer review * Address peer review * Detect mappings using the config NewSymbol event * DateChangeTimeKeeper performance improvement for time zone conversions * Clean up date change time keeper * Cleanup * Minor regression algo update * Cleanup * Cleanup * Fix perform universe selection on sundays for continuous futures with extended market hours * Cleanup * Address peer review * More cleanup * More cleanup
LEAN Data Formats
Introduction
From the beginning, LEAN has strived to use an open, human-readable data format - independent of any specific database or file format. From this core philosophy, we built LEAN to read its financial data from flat files on disk. Data compression is done in zip format, and all individual files are CSV or JSON.
When there is no activity for a security, the price is omitted from the file. Only new ticks and price changes are recorded.
File Data Format
Although we strive to make all data formats identical, it is often impossible. Below are links to dedicated documentation on the file format of the data in each asset type:
Equity | Forex | Options | Futures | Crypto
Folder Structure
Data files are separated and nested in a few predictable layers:
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Tick, Second and Minute Financial Data:
/data/securityType/marketName/resolution/ticker/date_tradeType.zip -
Hour, Daily Financial Data:
/data/securityType/marketName/resolution/ticker.zip
The marketName value is used to separate different tradable assets with the same ticker. E.g. EURUSD is traded on multiple brokerages all with slightly different prices.
Core Data Types
LEAN has a few core data types represented in all the asset classes we support. Below are links to their implementation in LEAN.
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TradeBar - TradeBar represents trade ticks of assets consolidated for a period. TradeBar file format is slightly different for high resolution (second, minute) and low resolution (daily, hour).
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QuoteBar - QuoteBar represents top of book quote data consolidated over a period of time (bid and ask bar).
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Tick - Tick data represents an individual record of trades ("trade ticks") or quote updates ("quote tick") for an asset. Tick data is instantaneous - it does not have a period.
Data Readers
All data is parsed from disk via Reader() methods. The Reader takes a single line of the file and converts it the appropriate type. i.e. TradeBar.Reader() method is a factory which returns TradeBar objects. When implementing custom data, Readers are used
Other Data Formats
Theoretically LEAN can accept data in any format (database, API or flatfile). However, in practice, we currently have reader implementations written for a flat file system.