B
If you go down the hierarchy, you have ApplyN, which defines a func parameter and is intended for your use case. See
Docs - Indicator Reference
class Logarithm(bt.ind.ApplyN):
params = (('func', lambda x: math.log(x[0])),)
In your case because func is defined at class level, the lambda is promoted to be a method and is therefore taking a self parameter, which doesn't happen, when func is defined as a parameter.
You should be able to directly do:
class LogPlot(bt.Indicator):
'''
Logarithmic plot
'''
lines = ('logplot',)
def __init__(self):
self.lines.logplot = bt.ind.ApplyN(self.data + 1, func=lambda x: math.log(x[0]))
which entirely forgoes having to define an indicator for something which simply is the application of a function over a period.
