Arrays across languages

Creating and working with arrays. Each row maps one concept from Lipi to the other languages; the word in a cell is the relation, explained in the language map overview.

Concept	Lipi	MQL4	MQL5	NinjaScript	Pine Script	thinkScript
Create an array	`array.new`, `array.from`, `array.new_float`, `array.new_int`	Caveat	Caveat	Caveat	Caveat	Absent
Arrays of drawing objects	`array.new_line`, `array.new_label`, `array.new_box`	Absent	Caveat	Caveat	Exact	Absent
Read and write an element	`array.get`, `array.set`	Caveat	Caveat	Caveat	Differs	Absent
Number of elements	`array.length`	Exact	Exact	Caveat	Caveat	Absent
Add or remove at the end	`array.push`, `array.pop`	Absent	Caveat	Caveat	Caveat	Absent
Add or remove at the start	`array.unshift`, `array.shift`	Absent	Caveat	Caveat	Caveat	Absent
Insert or remove at a position	`array.insert`, `array.remove`	Absent	Caveat	Caveat	Caveat	Absent
Empty or fill an array	`array.clear`, `array.fill`	Caveat	Caveat	Caveat	Exact	Absent
First and last element	`array.first`, `array.last`	Absent	Absent	Caveat	Exact	Absent
Find an element	`array.includes`, `array.indexof`, `array.lastindexof`, `array.binary_search`	Differs	Differs	Caveat	Caveat	Absent
Copy, slice and join arrays	`array.copy`, `array.slice`, `array.concat`	Caveat	Caveat	Caveat	Caveat	Absent
Sort and reverse	`array.sort`, `array.sort_indices`, `array.reverse`	Caveat	Caveat	Caveat	Caveat	Absent
Statistics of an array	`array.sum`, `array.avg`, `array.min`, `array.max`, `array.median`, `array.stdev`, `array.variance`	Differs	Differs	Caveat	Caveat	Absent
Array to text	`array.join`	Absent	Absent	Caveat	Exact	Absent
Test all or any elements	`array.every`, `array.some`	Absent	Absent	Caveat	Exact	Absent

Each section below gives the Lipi construct first, then the construct in each language, with a note wherever behaviour differs. The language name links to the documentation the row was checked against.

Create an array

Creates an array of the given length. In Lipi: array.new, array.from, array.new_float, array.new_int.

Language	Construct	Relation	Note
MQL4	`type name[n] declaration, ArrayResize, ArrayInitialize`	Equivalent, with a caveat	Fixed size at declaration, or a dynamic array sized with ArrayResize; fill values with ArrayInitialize. No from-values constructor. State and side effects: elements added by ArrayResize hold undefined values until you set them.
MQL5	`ArrayResize, ArrayInitialize`	Equivalent, with a caveat	Declare a dynamic array, size it with ArrayResize, then fill with ArrayInitialize. A brace list initialises a fixed array. New elements are undefined until set. State and side effects: Elements added by ArrayResize are not initialised to any value.
NinjaScript	`new List<double>()`	Equivalent, with a caveat	A List<T> grows like a Lipi array. new List<double>(n) only sets capacity: add n items to reach that length. C# arrays are fixed length.
Pine Script	`array.new<type>, array.from, array.new_float, array.new_int`	Equivalent, with a caveat	Lipi caps arrays at 10000 elements versus Pine’s 100000; array.new<bool>(n) holds na in Lipi.
thinkScript		Not in thinkScript	No script-created array. IDataHolder is the built-in series type (close, volume); rolling windows come from functions and fold.

Arrays of drawing objects

Creates an array of line IDs with size elements, each set to initial_value. In Lipi: array.new_line, array.new_label, array.new_box.

Language	Construct	Relation	Note
MQL4		Not in MQL4	Objects are named, not handles: ObjectCreate takes an object_name string, so keep an array of names.
MQL5	`string[] of object names with ObjectCreate`	Equivalent, with a caveat	Chart objects are addressed by a name string, unique per chart. Keep the names in a string array; there are no object id handles.
NinjaScript	List<IDrawingTool> (a typed list of draw objects)	Equivalent, with a caveat	Draw.* methods return draw objects you can add to a List<T>; entries are added as created, not preallocated with an initial value.
Pine Script	`array.new_line, array.new_label, array.new_box`	Exact
thinkScript		Not in thinkScript	No arrays and no line, label or box objects to hold in them.

Read and write an element

Returns the element at index. In Lipi: array.get, array.set.

Language	Construct	Relation	Note
MQL4	`array[index]`	Equivalent, with a caveat	Index operator, zero-based; an out-of-range access stops the program. A series-flagged array reverses the index direction. History indexing: ArraySetAsSeries makes index 0 the newest element; plain arrays count from the first.
MQL5	`array[index]`	Equivalent, with a caveat	Plain bracket indexing, 0-based; an out-of-range index stops the program. ArraySetAsSeries can flip direction so index 0 is the newest element. History indexing: With the as-series flag set, index 0 is the newest element; Lipi arrays always start at the first element.
NinjaScript	`list[index] (List<T> indexer)`	Equivalent, with a caveat	Index syntax instead of array.get and array.set; zero-based as in Lipi. Out-of-range access throws an exception.
Pine Script	`array.get, array.set`	Looks alike, behaves differently	Pine accepts negative indexes counting from the end (-1 is the last element). Lipi stops the script on any index outside 0 to length-1. History indexing: array.get(a, -1) is the last element in Pine and a runtime error in Lipi.
thinkScript		Not in thinkScript	No element read or write on a user array. Past bars of a series are read with [n] indexing or getValue inside fold.

Number of elements

Returns the number of elements in the array. In Lipi: array.length.

Language	Construct	Relation	Note
MQL4	`ArraySize`	Exact
MQL5	`ArraySize`	Exact
NinjaScript	List<T>.Count (C# arrays: Length)	Equivalent, with a caveat	A property, not a function call. A fixed-length C# array uses Length instead of Count.
Pine Script	`array.size`	Equivalent, with a caveat	Lipi has no array.size or a.size; use array.length(a) or a.length.
thinkScript		Not in thinkScript	No array length function; there are no user arrays.

Add or remove at the end

Appends value to the end of the array, growing it by one element. In Lipi: array.push, array.pop.

Language	Construct	Relation	Note
MQL4		Not in MQL4	No append or pop; grow with ArrayResize(array, n+1) and assign the last slot, read it and shrink to pop.
MQL5	`ArrayResize`	Equivalent, with a caveat	No push or pop: grow with ArrayResize and assign the last slot. To pop, read the last element, then shrink the array. State and side effects: A reserve_size argument avoids repeated reallocation; static arrays and indicator buffers cannot be resized.
NinjaScript	`List<T>.Add() with RemoveAt(Count - 1)`	Equivalent, with a caveat	Add appends like push. List<T> has no Pop: read the last element, then call RemoveAt(Count - 1).
Pine Script	`array.push, array.pop`	Equivalent, with a caveat	Pushing past 10000 elements stops a Lipi script; Pine allows 100000.
thinkScript		Not in thinkScript	No append or remove operations; a series cannot be grown or shrunk by script.

Add or remove at the start

Inserts value at the beginning of the array. In Lipi: array.unshift, array.shift.

Language	Construct	Relation	Note
MQL4		Not in MQL4	No front insert or removal; ArrayCopy moves ranges, but copying an array onto itself is documented as undefined.
MQL5	`ArrayRemove, ArrayInsert`	Equivalent, with a caveat	Remove index 0 with a count of 1; it returns a bool, not the element. ArrayInsert takes elements from a source array, not one value.
NinjaScript	`List<T>.Insert(0, value) and RemoveAt(0)`	Equivalent, with a caveat	Insert(0, value) matches unshift. List<T> has no Shift: read item 0, then RemoveAt(0). Both move every later element.
Pine Script	`array.unshift, array.shift`	Equivalent, with a caveat	Unshifting past 10000 elements stops a Lipi script; Pine allows 100000.
thinkScript		Not in thinkScript	No insert or remove at the start of a collection.

Insert or remove at a position

Inserts value at index, moving the element that was there, and every element after it, up one index. In Lipi: array.insert, array.remove.

Language	Construct	Relation	Note
MQL4		Not in MQL4	No insert or remove at a position; rebuild with ArrayCopy into a second array and ArrayResize.
MQL5	`ArrayInsert, ArrayRemove`	Equivalent, with a caveat	Insert copies elements from a source array at a destination index; remove takes a start and a count. Both return bool. State and side effects: On a fixed-size receiving array, the array’s own size does not change.
NinjaScript	`List<T>.Insert() and RemoveAt()`	Equivalent, with a caveat	Same effect as inserting and removing at an index; both are methods on the list. RemoveAt returns nothing, as array.remove does.
Pine Script	`array.insert, array.remove`	Equivalent, with a caveat	Pine’s array.remove returns the removed value; Lipi’s returns nothing. Pine accepts negative indexes for both; Lipi errors outside 0 to length-1. History indexing: A negative index counts from the end in Pine and stops the script in Lipi.
thinkScript		Not in thinkScript	No positional insert or remove on any collection.

Empty or fill an array

Removes every element, leaving an empty array. In Lipi: array.clear, array.fill.

Language	Construct	Relation	Note
MQL4	`ArrayFree, ArrayInitialize, ArrayFill`	Equivalent, with a caveat	ArrayFree empties dynamic arrays only; ArrayFill takes a start and a count, not an end index; ArrayInitialize sets every element. History indexing: ArrayFill always runs left to right and ignores the series-direction flag.
MQL5	`ArrayFree, ArrayFill, ArrayInitialize`	Equivalent, with a caveat	ArrayFree empties a dynamic array. ArrayFill takes a start and a count, not an end index, and ignores the as-series direction.
NinjaScript	`List<T>.Clear()`	Equivalent, with a caveat	Clear() empties the list. List<T> has no fill method; assign each index in a loop.
Pine Script	`array.clear, array.fill`	Exact
thinkScript		Not in thinkScript	No clear or fill; a number passed as IDataHolder is read as a series of that constant.

First and last element

Returns the first element of the array. In Lipi: array.first, array.last.

Language	Construct	Relation	Note
MQL4		Not in MQL4	No first or last helper; read array[0] and array[ArraySize(array)-1].
MQL5		Not in MQL5	No dedicated functions; use index 0 and ArraySize minus 1, which swap meaning when the array is as-series.
NinjaScript	`list[0] and list[list.Count - 1]`	Equivalent, with a caveat	No First or Last property on List<T>: index the ends directly. LINQ First() and Last() also exist.
Pine Script	`array.first, array.last`	Exact
thinkScript		Not in thinkScript	No first or last element accessor on user arrays; there are none.

Find an element

Returns true when value is one of the array’s elements. In Lipi: array.includes, array.indexof, array.lastindexof, array.binary_search.

Language	Construct	Relation	Note
MQL4	`ArrayBsearch`	Looks alike, behaves differently	Needs a sorted numeric array and, when the value is missing, returns the index of the nearest element, not -1 or false.
MQL5	`ArrayBsearch`	Looks alike, behaves differently	Needs a sorted array and returns the nearest element’s index when the value is absent, not -1. No includes or indexof function exists.
NinjaScript	`List<T>.Contains(), IndexOf(), LastIndexOf(), BinarySearch()`	Equivalent, with a caveat	Same job with close names. BinarySearch needs a sorted list.
Pine Script	`array.includes, array.indexof, array.lastindexof, array.binary_search`	Equivalent, with a caveat	Same results, -1 when missing. Pine’s binary_search target is named val (Lipi value) and has an extra sort_field overload for arrays of user types.
thinkScript		Not in thinkScript	No element search on collections. Highest, Lowest and GetMaxValueOffset locate extremes in a bar window only.

Copy, slice and join arrays

Returns a new array with the same elements. In Lipi: array.copy, array.slice, array.concat.

Language	Construct	Relation	Note
MQL4	`ArrayCopy`	Equivalent, with a caveat	Copies into an existing destination (grown as needed) and returns the copied count; slice by src_start and count, concat by dst_start. History indexing: copying runs left to right; series arrays have their start position adjusted for that. State and side effects: writes into the destination array; does not return a new array.
MQL5	`ArrayCopy`	Equivalent, with a caveat	Copies a range into an existing destination and returns the count copied. A slice is a partial copy; concat copies at a destination offset.
NinjaScript	`List<T>.GetRange() and AddRange()`	Equivalent, with a caveat	GetRange(index, count) copies a range given a start and a count; AddRange appends another collection.
Pine Script	`array.copy, array.slice, array.concat`	Equivalent, with a caveat	Both slices are live views of the original. Pine says insertions and removals in a slice change the original; Lipi says adding may detach storage. State and side effects: Growing a slice keeps writing through to the original in Pine; in Lipi it may separate from the original.
thinkScript		Not in thinkScript	No copy, slice or concatenate operations on collections.

Sort and reverse

Sorts the array in place. In Lipi: array.sort, array.sort_indices, array.reverse.

Language	Construct	Relation	Note
MQL4	`ArraySort`	Equivalent, with a caveat	Numeric arrays only, sorted in place, returning a bool. No sort_indices or reverse function. History indexing: the series-direction flag is taken into account when sorting.
MQL5	`ArraySort, ArrayReverse`	Equivalent, with a caveat	Ascending only, in place, ignoring the as-series flag. Sort descending with ArraySort then ArrayReverse. No index-sorting function.
NinjaScript	`List<T>.Sort() and Reverse()`	Equivalent, with a caveat	Sort() and Reverse() work in place, as array.sort and array.reverse do. There is no equivalent of sort_indices.
Pine Script	`array.sort, array.sort_indices, array.reverse`	Equivalent, with a caveat	Pine array.sort and sort_indices have a sort_field overload for arrays of objects; Lipi takes only id and order.
thinkScript		Not in thinkScript	No sort or reverse function; Median sorts internally over a window but exposes only the middle value.

Statistics of an array

Returns the sum of the array’s elements. In Lipi: array.sum, array.avg, array.min, array.max, array.median, array.stdev, array.variance.

Language	Construct	Relation	Note
MQL4	`ArrayMaximum, ArrayMinimum`	Looks alike, behaves differently	Return the index of the extreme element, not its value. Sum, average, median, deviation and variance have no array functions.
MQL5	`ArrayMaximum, ArrayMinimum, MathMean, MathMedian, MathStandardDeviation, MathVariance`	Looks alike, behaves differently	ArrayMaximum and ArrayMinimum return an index, not the value. Mean, median, deviation and variance are separate Math functions; there is no array sum. History indexing: The returned index honours the as-series flag of the array.
NinjaScript	`Enumerable.Sum(), Average(), Min(), Max() (System.Linq)`	Equivalent, with a caveat	LINQ covers sum, average, min and max. Median, standard deviation and variance are not in LINQ; compute them by hand. Needs using System.Linq.
Pine Script	array.sum, array.avg, array.min, array.max, array.median, array.stdev, array.variance	Equivalent, with a caveat	For int arrays Pine’s avg, median, stdev and variance return int; Lipi’s return float.
thinkScript		Not in thinkScript	No statistics on user arrays. Rolling statistics over bars come from Sum, Average, Highest, Lowest, Median and StDev.

Array to text

Joins the elements into one string, with separator between them. In Lipi: array.join.

Language	Construct	Relation	Note
MQL4		Not in MQL4	No array-to-text function; loop over the elements and append with StringConcatenate or +.
MQL5		Not in MQL5	No join function; build the text in a loop with StringConcatenate or StringAdd.
NinjaScript	`string.Join(separator, list)`	Equivalent, with a caveat	A static string method: separator first, then the collection of elements to join.
Pine Script	`array.join`	Exact
thinkScript		Not in thinkScript	No array-to-text function; there are no user arrays.

Test all or any elements

Returns true when every element is true. In Lipi: array.every, array.some.

Language	Construct	Relation	Note
MQL4		Not in MQL4	No all-or-any test over elements; loop and test each one.
MQL5		Not in MQL5	No all-true or any-true function in the array list; loop over the elements.
NinjaScript	`Enumerable.All() and Any() (System.Linq)`	Equivalent, with a caveat	LINQ All and Any take a condition function, so pass x => x for a list of bools. Needs using System.Linq.
Pine Script	`array.every, array.some`	Exact
thinkScript		Not in thinkScript	No all/any test on collections. A fold loop with a while condition can scan a bar window.

Manual

Use Lipi with AI

Reference

Arrays across languages

Create an array

Arrays of drawing objects

Read and write an element

Number of elements

Add or remove at the end

Add or remove at the start

Insert or remove at a position

Empty or fill an array

First and last element

Find an element

Copy, slice and join arrays

Sort and reverse

Statistics of an array

Array to text

Test all or any elements

​Create an array

​Arrays of drawing objects

​Read and write an element

​Number of elements

​Add or remove at the end

​Add or remove at the start

​Insert or remove at a position

​Empty or fill an array

​First and last element

​Find an element

​Copy, slice and join arrays

​Sort and reverse

​Statistics of an array

​Array to text

​Test all or any elements

Create an array

Arrays of drawing objects

Read and write an element

Number of elements

Add or remove at the end

Add or remove at the start

Insert or remove at a position

Empty or fill an array

First and last element

Find an element

Copy, slice and join arrays

Sort and reverse

Statistics of an array

Array to text

Test all or any elements