Research Environment
Object Store
Introduction
The Object Store is a file system that you can use in your algorithms to save, read, and delete data. The Object Store is organization-specific, so you can save or read data from the same Object Store in all of your organization's projects. The Object Store works like a key-value storage system where you can store regular strings, JSON encoded strings, XML encoded strings, and bytes. You can access the data you store in the Object Store from backtests, the Research Environment, and live algorithms.
Get All Stored Data
To get all of the keys and values in the Object Store, iterate through the ObjectStore
object_store
property.
foreach (var kvp in qb.ObjectStore) { var key = kvp.Key; var value = kvp.Value; }
for kvp in qb.object_store: key = kvp.key value = kvp.value
To iterate through just the keys in the Object Store, iterate through the Keys
keys
property.
foreach (var key in qb.ObjectStore.Keys) { continue; }
for key in qb.object_store.keys: continue
Create Sample Data
You need some data to store data in the Object Store.
Follow these steps to create some sample data:
- Create a dictionary.
- Create a
string
. - Create a
Bytes
object. - Convert the dictionary to an
XML
-formatted object.
var dictSample = new Dictionary<string, int> { {"One", 1}, {"Two", 2}, {"Three", 3} };
var stringSample = "My string";
string_sample = "My string"
var bytesSample = Encoding.UTF8.GetBytes("My String");
bytes_sample = str.encode("My String")
var xmlSample = new XElement("sample", dictSample.Select(kvp => new XElement(kvp.Key, kvp.Value))); Console.WriteLine(xmlSample.ToString());
Save Data
The Object Store saves objects under a key-value system. If you save objects in backtests, you can access them from the Research Environment.
If you run algorithms in QuantConnect Cloud, you need storage create permissions to save data in the Object Store.
If you don't have data to store, create some sample data.
You can save the following types of objects in the Object Store:
Bytes
objectsstring
objects- JSON objects
- XML-formatted objects
You can save Bytes
and string
objects in the Object Store.
Strings
To save a string
object, call the Save
save
or SaveString
save_string
method.
var saveSuccessful = qb.ObjectStore.Save($"{qb.ProjectId}/stringKey", stringSample);
save_successful = qb.object_store.save(f"{qb.project_id}/string_key", string_sample)
JSON
To save a JSON object, call the SaveJson<T>
method. This method helps to serialize the data into JSON format.
var saveSuccessful = qb.ObjectStore.SaveJson<Dictionary<string, int>>($"{qb.ProjectId}/jsonKey", dictSample);
XML
To save an XML-formatted object, call the SaveXml<T>
method.
var saveSuccessful = qb.ObjectStore.SaveXml<XElement>($"{qb.ProjectId}/xmlKey", xmlSample);
Bytes
To save a Bytes
object (for example, zipped data), call the SaveBytes
save_bytes
method.
var saveSuccessful = qb.ObjectStore.SaveBytes($"{qb.ProjectId}/bytesKey", bytesSample) var zippedDataSample = Compression.ZipBytes(Encoding.UTF8.GetBytes(stringSample), "data"); var saveSuccessful = qb.ObjectStore.SaveBytes($"{qb.ProjectId}/bytesKey.zip", zippedDataSample);
save_successful = qb.object_store.save_bytes(f"{qb.project_id}/bytes_key", bytes_sample) zipped_data_sample = Compression.zip_bytes(bytes(string_sample, "utf-8"), "data") zip_save_successful = qb.object_store.save_bytes(f"{qb.project_id}/bytesKey.zip", zipped_data_sample)
Read Data
To read data from the Object Store, you need to provide the key you used to store the object.
You can load the following types of objects from the Object Store:
Bytes
objectsstring
objects- JSON objects
- XML-formatted objects
You can load Bytes
and string
objects from the Object Store.
Before you read data from the Object Store, check if the key exists.
if (qb.ObjectStore.ContainsKey(key)) { // Read data }
if qb.object_store.contains_key(key): # Read data
Strings
To read a string
object, call the Read
read
or ReadString
read_string
method.
var stringData = qb.ObjectStore.Read($"{qb.ProjectId}/stringKey");
string_data = qb.object_store.read(f"{qb.project_id}/string_key")
JSON
To read a JSON object, call the ReadJson<T>
method.
var jsonData = qb.ObjectStore.ReadJson<Dictionary<string, int>>($"{qb.ProjectId}/jsonKey");
XML
To read an XML-formatted object, call the ReadXml<T>
method.
var xmlData = qb.ObjectStore.ReadXml<XElement>($"{qb.ProjectId}/xmlKey");
If you created the XML object from a dictionary, reconstruct the dictionary.
var dict = xmlData.Elements().ToDictionary(x => x.Name.LocalName, x => int.Parse(x.Value));
Bytes
To read a Bytes
object, call the ReadBytes
read_bytes
method.
var bytesData = qb.ObjectStore.ReadBytes($"{qb.ProjectId}/bytesKey");
byte_data = qb.object_store.read_bytes(f"{qb.project_id}/bytes_key")
Delete Data
Delete objects in the Object Store to remove objects that you no longer need. If you use the Research Environment in QuantConnect Cloud, you need storage delete permissions to delete data from the Object Store.
To delete objects from the Object Store, call the Delete
delete
method. Before you delete data, check if the key exists. If you try to delete an object with a key that doesn't exist in the Object Store, the method raises an exception.
if (qb.ObjectStore.ContainsKey(key)) { qb.ObjectStore.Delete(key); }
if qb.object_store.contains_key(key): qb.object_store.delete(key)
To delete all of the content in the Object Store, iterate through all the stored data.
foreach (var kvp in qb.ObjectStore) { qb.ObjectStore.Delete(kvp.Key); }
for kvp in qb.object_store: qb.object_store.delete(kvp.key)
Cache Data
When you write to or read from the Object Store, the notebook caches the data. The cache speeds up the notebook execution because if you try to read the Object Store data again with the same key, it returns the cached data instead of downloading the data again. The cache speeds up execution, but it can cause problems if you are trying to share data between two nodes under the same Object Store key. For example, consider the following scenario:
- You open project A and save data under the key
123
. - You open project B and save new data under the same key
123
. - In project A, you read the Object Store data under the key
123
, expecting the data from project B, but you get the original data you saved in step #1 instead.
You get the data from step 1 instead of step 2 because the cache contains the data from step 1.
To clear the cache, call the Clear
method.
qb.ObjectStore.Clear();
qb.object_store.clear()
Get File Path
To get the file path for a specific key in the Object Store, call the GetFilePath
get_file_path
method. If the key you pass to the method doesn't already exist in the Object Store, it's added to the Object Store.
var filePath = qb.ObjectStore.GetFilePath(key);
file_path = qb.object_store.get_file_path(key)
Storage Quotas
If you use the Research Environment locally, you can store as much data as your hardware will allow. If you use the Research Environment in QuantConnect Cloud, you must stay within your storage quota. If you need more storage space, edit your storage plan.
Example for DataFrames
Follow these steps to create a DataFrame, save it into the Object Store, and load it from the Object Store:
- Get some historical data.
- Create a DataFrame.
- Get the file path for a specific key in the Object Store.
- Call the SaveCsvto_csv method to save the DataFrame in the Object Store as a CSV file.
- Call the LoadCsvread_csv method to load the CSV file from the Object Store.
var spy = qb.AddEquity("SPY").Symbol; var history = qb.History(qb.Securities.Keys, 360, Resolution.Daily);
spy = qb.add_equity("SPY").symbol df = qb.history(qb.securities.keys, 360, Resolution.DAILY)
using Microsoft.Data.Analysis; // var columns = new DataFrameColumn[] { new DateTimeDataFrameColumn("Time", history.Select(x => (DateTime)x[spy].EndTime)), new DecimalDataFrameColumn("SPY Open", history.Select(x => (decimal)x[spy].Open)), new DecimalDataFrameColumn("SPY High", history.Select(x => (decimal)x[spy].High)), new DecimalDataFrameColumn("SPY Low", history.Select(x => (decimal)x[spy].Low)), new DecimalDataFrameColumn("SPY Close", history.Select(x => (decimal)x[spy].Close)) }; var df = new DataFrame(columns);
var filePath = qb.ObjectStore.GetFilePath("df_to_csv");
file_path = qb.object_store.get_file_path("df_to_csv")
DataFrame.SaveCsv(df, filePath); // File size: 26520 bytes
df.to_csv(file_path) # File size: 32721 bytes
var reread = DataFrame.LoadCsv(filePath);
reread = pd.read_csv(file_path)
pandas
supports saving and loading DataFrame objects in the following additional formats:
- XML
- JSON
- Parquet
- Pickle
file_path = qb.object_store.get_file_path("df_to_xml") df.to_xml(file_path) # File size: 87816 bytes reread = pd.read_xml(file_path)
file_path = qb.object_store.get_file_path("df_to_json") df.to_json(file_path) # File size: 125250 bytes reread = pd.read_json(file_path)
file_path = qb.object_store.get_file_path("df_to_parquet") df.to_parquet(file_path) # File size: 23996 bytes reread = pd.read_parquet(file_path)
file_path = qb.object_store.get_file_path("df_to_pickle") df.to_pickle(file_path) # File size: 19868 bytes reread = pd.read_pickle(file_path)
Example for Plotting
You can use the Object Store to plot data from your backtests and live algorithm in the Research Environment. The following example demonstrates how to plot a Simple Moving Average indicator that's generated during a backtest.
- Create a algorithm, add a data subscription, and add a simple moving average indicator.
- Save the indicator data as
string
in_content
self.content
. - In the OnEndOfAlgorithm method, save the indicator data to the Object Store.
- Open the Research Environment and create a
QuantBook
. - Read the indicator data from the Object Store.
- Convert the data to a pandas object and create a chart.
- Import the
Plotly.NET
andPlotly.NET.LayoutObjects
packages. - Create the
Layout
object and set thetitle
,xaxis
, andyaxis
properties. - Convert the data to a list of
DateTime
objects for the chart x-axis and a list ofdecimal
objects for the chart y-axis, then create aChart2D.Chart.Line
object with the data. - Apply the layout to the
Line
object and create theHTML
object.
public class ObjectStoreChartingAlgorithm : QCAlgorithm { private SimpleMovingAverage _sma; private string _content; public override void Initialize() { AddEquity("SPY", Resolution.Minute); _sma = SMA("SPY", 22); } }
class ObjectStoreChartingAlgorithm(QCAlgorithm): def initialize(self): self.add_equity("SPY") self.content = '' self._sma = self.sma("SPY", 22)
The algorithm will save _content
self.content
to the Object Store.
public override void OnData(Slice data) { _content += $"{_sma.Current.EndTime},{_sma}\n"; }
def on_data(self, data: Slice): self.plot('SMA', 'Value', self.sma.current.value) self.content += f'{self.sma.current.end_time},{self.sma.current.value}\n'
public override void OnEndOfAlgorithm() { ObjectStore.Save("sma_values_csharp", _content); }
def on_end_of_algorithm(self): self.object_store.save('sma_values_python', self.content)
// Execute the following command in first #load "../Initialize.csx" // Create a QuantBook object #load "../QuantConnect.csx" using QuantConnect; using QuantConnect.Research; var qb = new QuantBook();
qb = QuantBook()
var content = qb.ObjectStore.Read("sma_values_csharp");
content = qb.object_store.read("sma_values_python")
The key you provide must be the same key you used to save the object.
data = {} for line in content.split('\n'): csv = line.split(',') if len(csv) > 1: data[csv[0]] = float(csv[1]) series = pd.Series(data, index=data.keys()) series.plot()
#r "../Plotly.NET.dll" using Plotly.NET; using Plotly.NET.LayoutObjects;
var layout = new Layout(); layout.SetValue("title", Title.init("SMA")); var xAxis = new LinearAxis(); xAxis.SetValue("title", "Time"); layout.SetValue("xaxis", xAxis); var yAxis = new LinearAxis(); yAxis.SetValue("title", "SMA"); layout.SetValue("yaxis", yAxis);
var index = new List<DateTimee>(); var values = new List<decimal>(); foreach (var line in content.Split('\n')) { var csv = line.Split(','); if (csv.Length > 1) { index.Add(Parse.DateTime(csv[0])); values.Add(decimal.Parse(csv[1])); } } var chart = Chart2D.Chart.Linee<DateTime, decimal, stringe>(index, values);
chart.WithLayout(layout); var result = HTML(GenericChart.toChartHTML(chart));