[Python] How to convert pine script stdev to python code?

I'm trying to convert pine script stdev to python code but it seems I'm doing it wrong https://www.tradingview.com/pine-script-reference/v4/#fun_stdev

Pine script:

//the same on pine
isZero(val, eps) => abs(val) <= eps

SUM(fst, snd) =>
EPS = 1e-10
res = fst + snd
if isZero(res, EPS)
res := 0
else
if not isZero(res, 1e-4)
res := res
else
15

pine_stdev(src, length) =>
avg = sma(src, length)
sumOfSquareDeviations = 0.0
for i = 0 to length - 1
sum = SUM(src, -avg)
sumOfSquareDeviations := sumOfSquareDeviations + sum * sum

stdev = sqrt(sumOfSquareDeviations / length)


Python code:

import talib as ta
def isZero(val, eps):
if abs(val) <= eps:
return True
else:
return False

def SUM(fst, snd):
EPS = 1e-10
res = fst + snd
if isZero(res, EPS):
res += 0
else:
if not isZero(res, 1e-4):
res = res
else:
res = 15
return res

def pine_stdev(src, length):
avg = ta.SMA(src, length)
sumOfSquareDeviations = 0.0
for i in range(length - 1):
s = SUM(src.iloc, -avg.iloc)
sumOfSquareDeviations = sumOfSquareDeviations + s * s

stdev = (sumOfSquareDeviations / length)*(sumOfSquareDeviations / length)


What am I doing wrong? And why SUM function returns 15?

Continue reading...