Sort array alphabetically - educational

2023年1月14日

🔶   OVERVIEW


    • This educational script will sort an array of tickers alphabetically and place these values in an table, together with the according current price value next to each ticker.


🔶   SORT ALPHABETICALLY


🔹   I. We make a User Defined Type (UDT) obj, with:

        ·  ticker - the string name of the ticker
        ·  price - the current price (close)

    • From this UDT we make an object obj.new() for each ticker


🔹   II. 2 array's are made:

    • array of objects aObj, containing obj type obj.new() for every ticker
    • array of strings sort, the ticker part of each object obj.new()


🔹   III. Now we make an object of each ticker with the createObject(sym ) function

object_1 = createObject("TICKER")

    • the object object_1 consists off:
        ·  ticker -> "TICKER"
        ·  price -> current Daily close through request.security("TICKER") (non-repainting)
    • object_1 will be added to the aObj array
    • "TICKER" (string ticker part of object) will be added to the sort array


🔹   IV. The latter array is sorted alphabetically by using array.sort_indices()

EXAMPLE

originalArray = array.from("B", "A", "C")
indicesArray = [1, 0, 2] // sorted indices

array.get(originalArray, 1) -> "A"
array.get(originalArray, 0) -> "B"
array.get(originalArray, 2) -> "C"

IMPORTANT

Alphabetically sorting is case sensitive, just like Java compareTo(String anotherString)!
    • The comparison is based on the Unicode value of each character in the string, the lowest "Dec" values are sorted first in line.
    • Comparing the "Dec" values at unicodelookup explains why default CAPITAL lettres will be sorted first,
    • Default you would get this (A= 65, B= 66, a= 97, b= 98)

Aa
Ba
ab
bb

    • Adding str.lower(string) in the toLowerCase() function will result to the following:

Aa
ab
Ba
bb

   • (A= 65 is transformed to a= 97, ...)

   • As a side note, should you write "AMZN" as "ÀMZN" this would be placed at the end, even after transforming to lower case the "Dec" values are higher (À= 192, à= 224).

    • You can toggle "To Lower Case" to verify.


🔹   V. Values are placed in a table, using these sorted indices.

    • With the usage of UDTs and objects, the current price has the same index in the aObj as their ticker,
                  giving the advantage it is fairly easy to place every value correctly next to each other.
    • The same can be done by make 2 separate arrays, 1 for the current price, the other for "TICKER".


🔶   OTHER TECHNIQUES USED


    • Alternative technique for adding comment

        Instead of

//   this is a comment

        You can also do this:

_="   this is a comment  "

    • Alternate colour

        ·  During a loop, alternate colour when i is even or odd, using the modulo operation (%).
        ·  This is the remainder when dividing.

       EXAMPLE

        ·  3 % 2 = 1 -> 3 / 2 -> 1 * 2, 1 left (remainder)
        ·  4 % 2 = 0 -> 4 / 2 -> 2 * 2, 0 left (remainder)
        ·  5 % 2 = 1 -> 5 / 2 -> 2 * 2, 1 left (remainder)

for i = 0 to 10
    even  =  i  %  2  ==  0 
    col     = even ? thisColor : otherColor

    • Adjust colour in script by using colour picker



Cheers!

2023年1月14日

版本注释

Added "ignore_invalid_symbol= true" in "request.security()" function