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Doing simple math in a scan?
Is there a way to do basic math in a scan?
Lets say I want to eliminate stocks with big wicks and tails.
This is how I think I would do it in pseudo-code
Wick = High - Close
Tail = Close - Low
Body = Close – Open
Body = (abs) Body [Absolute Value]
Good-Stock = (($Wick + $Tail) <= (Body x 0.20))
Can this, or anything like it, be done in a scan?
If you take a little time with the documentation and/or tutorials, you will pick it up quickly. There really aren't many rules to master.
Intro is here, with links to topics:
Syntax is here (good place to start if you already program)
In your example, if you want the body to be more than 20 % of the range, you can write
and [absval(open - close) > range * .8]
You could also write
and [absval(open - close) > [high - low] * .8]
Basic rules for the scan engine
Every statement begins with “and” except the first one
Every statement, except the word “and”, goes between square brackets [ ]
NOTE: Parentheses are reserved for indicators and functions, like RSI(14) or max(10,close). If you need to group arithmetic expressions, use more square brackets, not parentheses: For instance:
And [ [high – close]/max(10, close) > 10]
Every statement contains a comparison operator. Valid operators are: is, is not, >, <, =, !=, >=, <=, x, contains, not contains.” !=” means “not equal to”. “x” means “crosses above”.
Every statement has one value preceding the operator and one value after the operator. Values can be indicators, overlays, numbers, reserved words like group, market cap, close, etc. (see drop downs on Advanced Scan page) or expressions using these values.
[group is SP500] // note: this would be a first scan statement because it doesn’t begin with “and”
And [MACD Line(12,26,9] > 20]
And [MACD Line(12,26,9) x MACD Signal(12,26,9)]
You can also write “or” statements. “Or” statements need to be isolated with an extra set of brackets
// begin scan
[group is sp500]
// get bullish and bearish crossovers
[ MACD Signal (12,26,9) x 20]
[ 80 x MACD Signal(12,26,9)]
// end scan
The double slashes "//" tell the scan engine to ignore everything on that same line that comes after the "//". So you can use that space to explain to yourself (for later) what you thought you were trying to do in the scan code.
NOTES on scan logic with “and” and “or”:
If a scan has ONLY “and” statements, all the “and” statements must be true for the scan to return a symbol.
If a scan has ONLY “or” statements, then only one condition must be true to return a symbol.
If a scan has a mix of “and” and “or” statements, the results depend on whether you isolated the “or” statement with extra brackets as shown above:
If you don’t use the brackets, then only one condition in the entire scan has to be true to return a symbol.
If you do use brackets, then every “and” condition must be true AND at least one “or” condition must be true to return a symbol.
It's actually harder to figure out WHAT to code for than HOW to actually write the code.
For instance, how would you code for a rising SMA 200?
You need to think about what would be true if the SMA 200 really is rising. First thought - the value today would be different from the value yesterday, or maybe 10 days ago or 100 days ago.
And it would be greater because it is rising. So the scan would compare today's SMA 200 to the past SMA 200 and it would be greater, so:
and [sma(200,close) > 10 days ago sma(200, close)]