FAQ & Code updates

guides/faq_and_code/README.md

@@ -4,32 +4,130 @@
 
 ## Introduction
 
-This is a compendium of frequently asked questions on Pine. Answers are short and often come with examples of code or links where more information can be found.
+This is a compendium of frequently asked questions on Pine. Answers are short and often come with examples of code or links where relevant information can be found.
 
 ### Table of Contents
 
-1. [AA](#script-structure)
+- [Built-in variables](#built-in-variables)
+- [Built-in functions](#built-in-functions)
+- [Plotting](#plotting)
+- [Indicators (a.k.a. studies)](#indicators)
+- [Strategies](#strategies)
+- [Alerts](#alerts)
+- [Techniques](#techniques)
 
-## What is the variable name for the current price? 
-The `close` variable holds both the price at the close of historical bars and the current price when code is running on the realtime bar.
 
-## What’s the code for a green candle?
+## BUILT-IN VARIABLES
+
+
+
+### What is the variable name for the current price? 
+The `close` variable holds both the price at the close of historical bars and the current price when an **indicator** is running on the realtime bar. If the script is a **strategy** running on the realtime bar, by default it runs only at the bar's close. If the `calc_on_every_tick` parameter of the `strategy()` declaration statement is set to `true`, the strategy will behave as an indicator and run on every price change of the realtime bar.
+
+### What is the code for a green candle?
 ```
-greenCandle = close>open
+greenCandle = close > open
 ```
+Once you have defined the `greenCandle` variable, if you wanted a boolean variable to be `true` when the 3 last candles were green ones, you could write:
+```
+threeGreenCandles = greenCandle and greenCandle[1] and greenCandle[2]
+```
+> Note that the variable name `3GreenCandles` would have caused a compilation error. It is not legal in Pine as it begins with a digit.
+
+
+
+## BUILT-IN FUNCTIONS
+
+
+
+## PLOTTING
+
+
+
+### Can I plot diagonals between two points on the chart?
+Yes, using the [`line.new()`](https://www.tradingview.com/pine-script-reference/v4/#fun_line{dot}new) function available in v4.
+
+
+
+## INDICATORS
+
+
+
+### Can I create an indicator that plots like the built-in Volume or Volume Profile indicators?
+No.
+
+
+
+## STRATEGIES
+
 
-## How do I make an alert available from my indicator?
+
+### How do I implement date range filtering in strategies?
+```
+DateFilter = input(false, "═════════════ Date Range Filtering")
+FromYear = input(1900, "From Year", minval=1900)
+FromMonth = input(1, "From Month", minval=1, maxval=12)
+FromDay = input(1, "From Day", minval=1, maxval=31)
+ToYear = input(2999, "To Year", minval=1900)
+ToMonth = input(1, "To Month", minval=1, maxval=12)
+ToDay = input(1, "To Day", minval=1, maxval=31)
+FromDate = timestamp(FromYear, FromMonth, FromDay, 00, 00)
+ToDate = timestamp(ToYear, ToMonth, ToDay, 23, 59)
+TradeDateIsAllowed() => DateFilter? (time >= FromDate and time <= ToDate) : true
+```
+You can then use the result of `TradeDateIsAllowed()` to confirm your entries using something like this:
+```
+EnterLong = GoLong and TradeDateIsAllowed()
+```
+> Note that with this code snippet, date filtering can be enabled/disabled using a checkbox. This way you don't have to reset dates when filtering is no longer needed; just uncheck the box.
+
+
+
+## ALERTS
+
+
+
+### How do I make an alert available from my indicator?
+Two steps are required:
+1. Insert an `alertcondition()` call in an indicator script.
+2. Create an alert from the TV Web user interface (ALT-A) and choose the script's alert condition.
+
+See the User Manual page on [`alertcondition()`](https://www.tradingview.com/pine-script-docs/en/v4/annotations/Alert_conditions.html). Code to create an alert condition looks like:
 ```
-triggerCondition = close>close[1]
-alertcondition(triggerCondition, title="Create Alert dialog box name", message="Text sent with alert.")
+triggerCondition = close > close[1]
+alertcondition(triggerCondition, title = "Create Alert dialog box name", message = "Text sent with alert.")
 ```
-When you need to create multiple alerts you can repeat the method above for every alert you want your indicator to generate, but you can also use the method shown in [this indicator](https://www.tradingview.com/script/8AUuFonD-5-MAs-w-alerts-LucF/). Here, all the different alert conditions are bunched up in one `alertcondition()` statement. In this case, you must provide the means for users to first select which conditions will trigger the alert in the *Inputs* dialog box. When all the required conditions are selected, the user creates an alert using the only alert this indicator makes available, but since TradingView remembers the state of the *Inputs* when creating an alert, only the selected conditions will trigger the alert once it’s created, even if Inputs selections are modified by the user after the alert is created.
+When you need to create multiple alerts you can repeat the method above for every alert you want your indicator to generate, but you can also use the method shown in [this indicator](https://www.tradingview.com/script/8AUuFonD-5-MAs-w-alerts-LucF/). Here, all the different alert conditions are bunched up in one `alertcondition()` statement. In this case, you must provide the means for users to first select which conditions will trigger the alert in the *Inputs* dialog box. When all the required conditions are selected, the user creates an alert using the only alert this indicator makes available, but since TradingView remembers the state of the *Inputs* when creating an alert, only the selected conditions will trigger the alert once it’s created, even if *Inputs* selections are modified by the user after the alert is created.
 
 When more than one condition can trigger a single alert, you will most probably need to have visual cues for each condition so that when users bring up a chart on which an alert triggered they can figure out which condition caused the alert to trigger. This is a method that allows users of your script to customize the alert to their needs.
 
-When TradingView creates an alert, it saves a snapshot of the environment that will enable the alert to run on the servers. The important elements saved with an alert are:
+When TradingView creates an alert, it saves a snapshot of the environment that will enable the alert to run on the servers. The elements saved with an alert are:
 - Current symbol,
-- Current time frame (interval),
-- State of the scipt's Inputs selections,
+- Current time frame,
+- State of the script's *Inputs* selections,
 - Current version of the script. Subsequent updates to the script’s code will not affect the alerts created with prior versions.
-Also note that alerts are not available from within strategies.
+
+> Note that while alert condition code will compile in strategy scripts, they are only functional in studies.
+
+### I have a custom script that generates alerts. How do I run it on many symbols?
+You need to create a separate alert for each symbol. There is currently no way to create an alert for all the symbols in a watchlist or for the Screener.
+
+If one of the generic indicators supplied with the Screener suits your needs and your symbols are tagged with a color label, you can create an alert on those markets from within the Screener.
+
+
+
+## TECHNIQUES
+
+
+
+### How do I save a value or state for later use?
+Backtest Rookies has a [blog post](https://backtest-rookies.com/2018/11/23/tradingview-save-a-variable-store-a-value-for-later/) on the subject.
+Pine Example: [Holding a state in a variable](https://www.tradingview.com/script/llcoIPKG-Pine-Example-Holding-a-state-in-a-variable/) by vitvlkv.
+
+### How do I calculate averages?
+1. If you just want the average between two values, you can use `avg(val1, val2)` or `(val1 + val2)/2`.
+1. To average the last x values in a series, you can use `sma(series, x)`.
+
+### How can I calculate averages only when a condition is true?
+[This script](https://www.tradingview.com/script/isSfahiX-Averages-PineCoders-FAQ/) shows how to calculate a conditional average using three different methods.
+