What am I doing wrong here?

[cept0r]

Okay I'm a relatively noob coder but im trying to replicate my manual trading strategy and automate it. In my head from a trader's perspective its so simple but im having a really hard time coding it out. Luckily I got plenty of time.

What am I doing wrong here;

import btalib


class Cstdev(btalib.stddev, btalib.linearreg_slope):
    alias = ('STDDEV',)
    lines = dict(period=14,
                 movav=btalib.linearreg_slope),
    params = (
        ('ddof', 0),
        ('period', 0)
    )

    def __init__(self):
        self.upper_dev1 = btalib.stddev(ddof=0.1, period=2)
        self.upper_dev2 = btalib.stddev(ddof=0.2, period=2)
        self.upper_dev3 = btalib.stddev(ddof=0.3, period=2)
        self.upper_dev4 = btalib.stddev(ddof=0.4, period=2)
        self.lower_dev1 = btalib.stddev(ddof=-0.1, period=2)
        self.lower_dev2 = btalib.stddev(ddof=-0.2, period=2)
        self.lower_dev3 = btalib.stddev(ddof=-0.3, period=2)
        self.lower_dev4 = btalib.stddev(ddof=-0.4, period=2)

Getting this output:

btalib.errors.InputsError: One (1) input is at least needed and 0 were provided

[cept0r]

What I want is to create 4x "bands" using linear regression slope as the "moving average/mean" and stddev as the bands. I don't have to use these indicators if there are easier ways to implement this.

Thanks in advance!

Regards,

cept0r

[cept0r]

Oh just realized that I'm not supposed to use bta-lib with backtrader, I'll go back to inhereting bt.indicators and ill use ema as a mean just so I can get started.