Ultimate Algorithmic Trading System

In Python variables are assigned values with the equal sign (=). Equality between
two variables is verified by using a double equal sign (==). Jump over to the Python
Shell really quick. I hope you still have it close at hand. There might be a bunch of
stuff in the window, so just scroll down to the very bottom until you find the >>>
prompt. Once there type a = 5 and hit enter. Type a and hit enter. The number 5
should appear at the prompt. You have basically assigned 5 to the variable a. Now
type b = 5 and hit enter. Type a==b and hit enter. The prompt should return with
True. In this case a equals b. Type a!= b and hit enter. The prompt will return
with False, becausea does equal b. Youareaskingifa doesn’t equal b and the
answer is False because it does. Remember to use == to test for equality and !=
for inequality.
The next line of code is very important because you will see it often.
for index in range((curBar - offset) - (lookBack-1), curBar - offset +1):
This is an example of a definite loop; the number of repetitions is known ahead
of time. This for-loop will iterate across the number of items in the range
from ((curBar − offset) − (lookBack−1) to curBar − offset +1). This only looks
complicated because of the variables in the range function. Here is a more
simplified version of the Python for loop:
173
myList = list()
myList = [1,2,3,4]
for index in range(0,3):
print(myList[index])
The output of this code will print only the first three elements in the list named
myList. The function Range(0,3) returns 0, 1, and 2. The upper bound in the
Range function is not inclusive. So to print out myList in its entirety, you must
use Range(0,4). Referring back to the original bounds in our Range function, let’s
simplify by substituting some numbers for the values. Assume:
curBar = 500
offset = 1
lookback = 20
USING PYTHON TO BACKTEST YOUR ALGORITHM
So, range ((500 − 1) − (20 −1), 500 − 1 + 1) equals range (499 − 19, 500).
The loop will iterate from 480 to 499 because 500 isn’t included. Since 480 is
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