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Custom Securities

CSV Format Example

Introduction

This page explains how to import custom data of a single security sourced in CSV format.

Data Format

The following snippet shows an example CSV file:

Date,Open,High,Low,Close,SharesTraded,Tur11er(Rs.Cr)
1997-01-01,905.2,941.4,905.2,939.55,38948210,978.21
1997-01-02,941.95,944,925.05,927.05,49118380,1150.42
1997-01-03,924.3,932.6,919.55,931.65,35263845,866.74
...
2014-07-24,7796.25,7835.65,7771.65,7830.6,117608370,6271.45
2014-07-25,7828.2,7840.95,7748.6,7790.45,153936037,7827.61
2014-07-28,7792.9,7799.9,7722.65,7748.7,116534670,6107.78

The data in the file must be in chronological order.

Define Custom Types

To define a custom data type, inherit the PythonData class and override the GetSource and Reader methods.

Select Language: 
class MyCustomDataType(PythonData):

    def get_source(self,
         config: SubscriptionDataConfig,
         date: datetime,
         is_live: bool) -> SubscriptionDataSource:

        if not is_live:
            return SubscriptionDataSource("<custom_data_key>", SubscriptionTransportMedium.OBJECT_STORE, FileFormat.CSV)
        return SubscriptionDataSource("https://raw.githubusercontent.com/QuantConnect/Documentation/master/Resources/datasets/custom-data/csv-data-example.csv", SubscriptionTransportMedium.REMOTE_FILE)

    def reader(self,
         config: SubscriptionDataConfig,
         line: str,
         date: datetime,
         is_live: bool) -> BaseData:

        if not (line.strip()):
            return None

        index = MyCustomDataType()
        index.symbol = config.symbol

        try:
            data = line.split(',')
            index.time = datetime.strptime(data[0], "%Y-%m-%d")
            index.end_time = index.time + timedelta(days=1)
            index.value = data[4]
            index["open"] = float(data[1])
            index["high"] = float(data[2])
            index["low"] = float(data[3])
            index["close"] = float(data[4])

        except ValueError:
            # Do nothing
            return None

        return index

Create Subscriptions

To create a subscription for the custom type, in the initialize method, call the add_data method. The add_data method returns a Security object, which contains a Symbol. Save a reference to the symbol so you can use it in on_data to access the security data in the Slice.

Select Language: 
class MyAlgorithm(QCAlgorithm): 
    def initialize(self) -> None:
        self._symbol = self.add_data(MyCustomDataType, "MyCustomDataType", Resolution.DAILY).symbol

The add_data method creates a subscription for a single custom data asset and adds it to your user-defined universe.

Receive Custom Data

As your data reader reads your custom data file, LEAN adds the data points in the Slice it passes to your algorithm's on_data method. To collect the custom data, use the symbol or name of your custom data subscription. You can access the value and custom properties of your custom data class from the Slice. To access the custom properties, pass the property name to the get_property method.

Select Language: 
class MyAlgorithm(QCAlgorithm):
    def on_data(self, slice: Slice) -> None:
        if slice.contains_key(self._symbol):
            custom_data = slice[self._symbol]
            close = custom_data.close

If you add custom properties to your data object in the reader method, LEAN adds them as members to the data object in the Slice. To ensure the property names you add in the reader method follow the convention of member names, LEAN applies the following changes to the property names you provide in the reader method:

  1. - and . characters are replaced with whitespace.
  2. The first letter is capitalized.
  3. Whitespace characters are removed.

For example, if you set a property name in the reader method to ['some-property.name'], you can access it in the on_data method through the Somepropertyname member of your data object.

Demonstration Algorithms

BubbleAlgorithm.py Python CustomDataNIFTYAlgorithm.py Python DescendingCustomDataObjectStoreRegressionAlgorithm.py Python

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