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--- curves [2020/07/30 16:06] – atolstov
+++ curves [2022/05/24 08:52] (current) – [Get value from the curve via Lua] emozolyak
@@ Line 1: / Line 1: @@
+{{ network:menu-icon-curves.png?nolink&60|}}
 ======Curves======
 =====Introduction=====
@@ Line 4: / Line 5: @@
 Curve is a way to define output value from a pre-defined pair table of a discrete set of known data points. Such as standard or desired value.
-It can be represented as a black-box, where is some **INPUT x** have corresponding **OUTPUT y** = f(x)
+Curve can be represented as a function f, which is a blackbox, where is some **INPUT x** have corresponding **OUTPUT y** = f(x)
 Curve is using a piecewise linear interpolation, is a curve fitting which is a allow to using linear polynomials to construct new data points within the range of a discrete set of known data points.
@@ Line 55: / Line 56: @@
 {{ :curve:c6.png?direct&600 |}}\\
 =====Select a curve to put in register=====
-First, to get value from curve you need the curves and the register pre-created.
+To get the value you need:
-Now, it is time to create a register with value type "String".
+  - Have a curve
+  - Have a string register for dashboard element to put selected curve in it
+  - Optionally, have yet another string register for store that curve all the time
+Now, it is time to create a register with value type "String" for dashboard element.
 Then, create a new dashboard.
@@ Line 85: / Line 89: @@
 {{ :curve:reg_filled_with_equat.png?direct&600 |}}
-=====Get value from the curve=====
+=====Get value from the curve via Lua =====
 To get the **OUTPUT y value** from existing(pre-created) curve, you need:
@@ Line 95: / Line 99: @@
 <code lua - curves.lib>
-function GetCurveValue ( curve_register, x_to_find_y  )
+--[[
-    --[[
+The function does curve conversion f(inputValue) = outputValue
-    --Curve handler
+Example of a curve, having multiple ranges of kx + b, set in a register of a String type with Json
-    INPUT:
+[{"k":4.167,"b":0,"range":[0,3]},{"k":0,"b":12.5,"range":[3,27]},{"k":-4.167,"b":125,"range":[27,30]}]
-        Put curve register as first argument and X coordinate as second.
+--]]
-    OUTPUT:
+function getCurveValue (curveReg, inputValue)
-        Get as result status if it is inside curve range of outside(false) and the Y value as second output argument
+    local s, e = 1, 2                           -- start & end indexes of the subranges
+    local tab = cjson.decode( R(curveReg) )
+    local outputValue, stickOutflag
-    EXAMPLE:
+    for _, sub_ in ipairs(tab) do
-        curve_status, value = GetCurveValue( "curve_for_current_hour", current_hour )
+        if ( (sub_.range[s] <= inputValue) and (inputValue < sub_.range[e]) ) then
-    --]]
+            return (inputValue * sub_.k + sub_.b), nil                             -- normal sequence
-    table = cjson.decode( R ( curve_register ) )
-    -- inRangeCurve( table, x_to_find_y )
-    for _, value in ipairs( table ) do --piecewise handler inside range of the curve
-        if ( value.range[1] <= x_to_find_y and x_to_find_y < value.range[2] ) then
-            -- in_range_status, index_curve_piece, y = true, index, curveLinearCalc( x_to_find_y, value.k, value.b )
-            in_range_status, y = true, ( x_to_find_y * value.k + value.b )
-            return in_range_status, y
         end
     end
-    if  x_to_find_y < table[1].range[1] then -- behaivior for outside left-sided
+    -- edge cases
-        -- in_range_status, index_curve_piece, y = false, 1, curveLinearCalc( table[1].range[1], table[1].k*0, table[1].b ) --table[1].b
+    if  (inputValue < tab[s].range[s]) then
-        in_range_status, index_curve_piece, y = false, 1, ( table[1].range[1] * table[1].k + table[1].b ) --table[1].b
+        outputValue = tab[s].range[s] * tab[s].k + tab[s].b
-        return in_range_status, y
+        stickOutflag = 1
-    elseif x_to_find_y > table[#table].range[2] then -- behaivior for outside right-sided
+    elseif (inputValue > tab[#tab].range[e]) then
-        -- in_range_status, index_curve_piece, y = false,#table,curveLinearCalc( table[#table].range[2], table[#table].k, table[#table].b ) --table[#table].b
+        outputValue = tab[#tab].range[e] * tab[#tab].k + tab[#tab].b
-        in_range_status,  y = false,#table,( table[#table].range[2] * table[#table].k + table[#table].b)
+        stickOutflag = #tab
-        return in_range_status, y
     end
+    return outputValue, stickOutflag
-    return in_range_status, y
 end
 </code>
 Example of usage:
 <code lua - Getter>
 include "curves.lib"
 function main (userId)
+    local SAFE_VALUE = 10
-    local t = os.date("*t", os.time())
+    local curHour = tonumber( os.date("*t", os.time()).hour )
-    current_hour = tonumber(t.hour)
+    INFO("curHour "  .. curHour)
-    curve_status, y = GetCurveValue( "curve_for_current_hour", current_hour )
+    local y, valueOutOfRange = getCurveValue("curve_for_curHour", curHour)
-    WriteReg("value_for_current_hour", y)
+    if (not valueOutOfRange) then
+        W("value_for_curHour", y)  -- WriteReg
+    else
+        W("value_for_curHour", SAFE_VALUE)
+    end
 end
 </code>