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def supres(ltp, n):

"""

This function takes a numpy array of last traded price

and returns a list of support and resistance levels

respectively. n is the number of entries to be scanned.

"""

from scipy.signal import savgol_filter as smooth

#converting n to a nearest even number

if n%2 != 0:

n += 1

n_ltp = ltp.shape[0]

# smoothening the curve

ltp_s = smooth(ltp, (n+1), 3)

#taking a simple derivative

ltp_d = np.zeros(n_ltp)

ltp_d[1:] = np.subtract(ltp_s[1:], ltp_s[:-1])

resistance = []

support = []

for i in xrange(n_ltp - n):

arr_sl = ltp_d[i:(i+n)]

first = arr_sl[:(n/2)] #first half

last = arr_sl[(n/2):] #second half

r_1 = np.sum(first > 0)

r_2 = np.sum(last < 0)

s_1 = np.sum(first < 0)

s_2 = np.sum(last > 0)

#local maxima detection

if (r_1 == (n/2)) and (r_2 == (n/2)):

resistance.append(ltp[i+((n/2)-1)])

#local minima detection

if (s_1 == (n/2)) and (s_2 == (n/2)):

support.append(ltp[i+((n/2)-1)])

return support, resistance

kudos if you designed it ..get approach to determine S&R

A minor amendment in the function.

In the case there is no support or resistance, the function doesn't run properly.

To fix it, we need to add try/pass before the end of the function. The return will be an empty list, which is fine.

Follows the amendment:

Thanks,

Arthur

1. From points, he derived smooth curve

2. Calculated delta for slope = dy/dx and as time between two candles is constant, dx = 1

3. ltp_d is dy/dx wth dx = 1, so dy (ltp_d, means ltp delta) is nothing but difference of adjacent prices

4. Then a window of n candles arr_sl is panned over ltp_d array

5. And during this panning, at any point, where the mid point of this window has positive and negative delta count same, means it is minima or maxima

6. If first half count is positive and second half is negative, it means maxima and visa versa

Use this 1 minute candle ltp to find and then trade on 5 minute candle chart

Or use this for 30 minute candle to then use result to trade on positional

Catch is that you must use this for candles of time much lower than your trading candle chart

What would be a good value for 'n' when working with daily close prices here for positional trades?

Thanks!