I'm working through the book Trading Evolved by Andreas Clenow and am running into an AssertionError when trying to run the code for the first backtest on zipilne. I am new to python and zipline and appreciate any guidance on how to solve this error. Here is the source code taken from the book's website:
# This ensures that our graphs will be shown properly in the notebook.
%matplotlib inline
#Import pandas as pd
import pandas as pd
# Import Zipline functions that we need
from zipline import run_algorithm
from zipline.api import order_target_percent, symbol
# Import date and time zone libraries
from datetime import datetime
import pytz
# Import visualization
import matplotlib.pyplot as plt
def initialize(context):
# Which stock to trade
context.stock = symbol('AAPL')
# Moving average window
context.index_average_window = 100
def handle_data(context, data):
# Request history for the stock
equities_hist = data.history(context.stock, "close",
context.index_average_window, "1d")
# Check if price is above moving average
if equities_hist[-1] > equities_hist.mean():
stock_weight = 1.0
else:
stock_weight = 0.0
# Place order
order_target_percent(context.stock, stock_weight)
def analyze(context, perf):
fig = plt.figure(figsize=(12, 8))
# First chart
ax = fig.add_subplot(311)
ax.set_title('Strategy Results')
ax.semilogy(perf['portfolio_value'], linestyle='-',
label='Equity Curve', linewidth=3.0)
ax.legend()
ax.grid(False)
# Second chart
ax = fig.add_subplot(312)
ax.plot(perf['gross_leverage'],
label='Exposure', linestyle='-', linewidth=1.0)
ax.legend()
ax.grid(True)
# Third chart
ax = fig.add_subplot(313)
ax.plot(perf['returns'], label='Returns', linestyle='-.', linewidth=1.0)
ax.legend()
ax.grid(True)
# Set start and end date
start_date = datetime(1996, 1, 1, tzinfo=pytz.UTC)
end_date = datetime(2018, 12, 31, tzinfo=pytz.UTC)
# Fire off the backtest
results = run_algorithm(
start=start_date,
end=end_date,
initialize=initialize,
analyze=analyze,
handle_data=handle_data,
capital_base=10000,
data_frequency = 'daily', bundle='quandl'
)
After running this I get the below error.
---------------------------------------------------------------------------
AssertionError Traceback (most recent call last)
<ipython-input-23-0e4e6c712343> in <module>()
75 handle_data=handle_data,
76 capital_base=10000,
---> 77 data_frequency = 'daily', bundle='quandl'
78 )
79
/opt/anaconda3/envs/zipenv/lib/python3.5/site-packages/zipline/utils/run_algo.py in run_algorithm(start, end, initialize, capital_base, handle_data, before_trading_start, analyze, data_frequency, bundle, bundle_timestamp, trading_calendar, metrics_set, benchmark_returns, default_extension, extensions, strict_extensions, environ, blotter)
391 environ=environ,
392 blotter=blotter,
--> 393 benchmark_spec=benchmark_spec,
394 )
395
/opt/anaconda3/envs/zipenv/lib/python3.5/site-packages/zipline/utils/run_algo.py in _run(handle_data, initialize, before_trading_start, analyze, algofile, algotext, defines, data_frequency, capital_base, bundle, bundle_timestamp, start, end, output, trading_calendar, print_algo, metrics_set, local_namespace, environ, blotter, benchmark_spec)
200 trading_calendar=trading_calendar,
201 capital_base=capital_base,
--> 202 data_frequency=data_frequency,
203 ),
204 metrics_set=metrics_set,
/opt/anaconda3/envs/zipenv/lib/python3.5/site-packages/zipline/finance/trading.py in __init__(self, start_session, end_session, trading_calendar, capital_base, emission_rate, data_frequency, arena)
36 arena='backtest'):
37
---> 38 assert type(start_session) == pd.Timestamp
39 assert type(end_session) == pd.Timestamp
40
AssertionError:
Appreciate any help on how to solve this.