Hi everyone,
I can't find detailed instruction on how to understand the use of context
and data
in handle_data
to access fetched data.
I have some specific questions related to the following example below:
def initialize(context):
# a signal Fetcher
fetch_csv('http://priceoftea.com/', symbol='tea')
# a security info Fetcher
fetch_csv('http://insiderselling.com')
why does not use the following code here?
context.stock = symbol('XYZ')
def handle_data(context, data):
# guard against being called before the first trade of a security
if symbol('XYZ') in data:
# guard against trades happening before the first insider selling event
if 'insider' in data[symbol('XYZ')]:
if data[symbol('XYZ')]['insider'] > 10.0:
order(symbol('XYZ'), -100)
# signal data will pass a blank place holder if the first event has not been sent yet.
# So, you can just guard against missing properties
if 'price' in data['tea']:
record(price_of_tea=data['tea']['price'])
does
symbol('XYZ')
data come from site 'http://insiderselling.com'?how
context
anddata
differentiate from each other?
what are the jobs ofcontext
anddata
?
how do they complete their jobs differently?
also,data
can not be used to calculate custom indicator, we have to usecontext.stock
, is it right?