Loops, While

[Vision]

Does thinkscript allow you to create a loop which is always testing for conditions without using a set number of iterations as required by fold? Could you use multiple switch statements with only one operation in each?

 

[halcyonguy]

yes, while , can be used in a fold loop.
here is an example.
https://usethinkscript.com/threads/...st-65-most-recent-days.7483/page-2#post-72474


if you search this site for fold you should find some codes that use while.

another good source of info
https://jshingler.github.io/TOS-and...t Collection.html#the-fold-function-explained

 

[Vision]

Thanks.

input lookback = 40;
# if while is used, fold loops as long as while statement is true
# when while becomes false, the loop stops, even if fold hasn't reached the highest count value
def bigbarcnt = fold k = 1 to lookback
with p
while (high > getvalue(high, k) and low < getvalue(low, k))
do p + 1;

What happens when lookback reaches 41? Does the while process stop? Does it keep going but start over? To keep this code operating like a traditional while statement and to be safe would a very large lookback number be used so the condition will be found before the lookback is reached?

 

[Joshua]

ThinkScript itself is already iterated on a bar by bar basis; all variables, functions, etc., are essentially arrays. The fold terminates at to, the fold can be interrupted prematurely by while. The fold itself executes every bar, so for example, in this particular case, on bar 60 it will fold back to bar 20 unless interrupted. On bar 61 it will fold back to bar 21, and so on.

In the case of a continuous non-terminating loop, you simply rely on the primary iteration itself, combined with logical statements. A variable can always be assigned its prior value, ie X = X[1], to maintain its persistence throughout the primary iteration. This type of operation will naturally begin at the beginning of the chart, and continue as new data arrives indefinitely.

May I ask; what is it exactly that you are trying to do?

 

[Vision]

I'm trying to create: if condition1 and condition2 happened, while condition2 is happening do an action.
In another language it would be easy, use an if then with a while statement. Or maybe use a flag.

 

[Vision]

Thanks for the help guys, figured this out.

 

[halcyonguy]

Thanks.

input lookback = 40;
# if while is used, fold loops as long as while statement is true
# when while becomes false, the loop stops, even if fold hasn't reached the highest count value
def bigbarcnt = fold k = 1 to lookback
with p
while (high > getvalue(high, k) and low < getvalue(low, k))
do p + 1;

What happens when lookback reaches 41? Does the while process stop? Does it keep going but start over? To keep this code operating like a traditional while statement and to be safe would a very large lookback number be used so the condition will be found before the lookback is reached?

i updated the link in my post #2.
in that code i ran a loop to 40, to look for a condition, that i thought should happen within 20 bars.

if you are unsure when a condition would become true to trigger the while statement, yes, you can loop to a big number. i would keep it < 500. experiment to find out what is realistic.
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lookback is a constant, it won't change. it will be 40 until the user types in a different number.

regarding this, and assuming there is no while statement,

input lookback = 40;
fold k = 1 to lookback...

with a to value of 40,
on each bar, k will count up to 39.
when k=39 , it will process the formulas within the loop, then stop. k won't reach 40. it won't process k being equal to 40.

if a while statement is used in a fold, and the while formula becomes false, the loop will stop and the program will procede to the next code line.