This code snippet demonstrates how to perform a volume by price analysis using the ProBuilder programming language. The code calculates the volume at each price level within the range of the highest and lowest prices of the current chart and visualizes this data as segments on the chart.

defparam DRAWONLASTBARONLY = true
if IsLastBarUpdate and not isset($somme[0]) then
    Y3Rmax = round(highest[barindex](high))
    Y3Rmin = round(lowest[barindex](low))
    for x = 0 to barindex-1
        xi = barindex - x
        LowR = round(low[xi])
        HighR = round(high[xi])
        for i = LowR to HighR
            if isset($X2[i]) then
                //Le prix a déjà été atteint, on ajoute 1
                $X2[i] = $X2[i]+1
            else
                //Toute première fois que le prix est atteint, on le crée
                $X2[i] = 1
                $Y2R[i] = i
            endif
        next
    next
    Somme = 0
    for i = Y3Rmin to Y3Rmax
        Somme = Somme + $X2[i]
    next
    $somme[0]=somme
    $Y3Rmax[0] = Y3Rmax
    $Y3Rmin[0] = Y3Rmin
endif

if isset($somme[0]) then
    for i = $Y3Rmin[0] to $Y3Rmax[0]
        DRAWSEGMENT(0, $Y2R[i], $X2[i], $Y2R[i])
        style(line,5)
    next
endif

return

The code snippet above is structured to execute only on the last update of the bar, ensuring that calculations are only performed once per bar, optimizing performance. Here’s a step-by-step breakdown:

• Initialization: The defparam DRAWONLASTBARONLY = true directive ensures that drawing commands are executed only on the last bar to avoid unnecessary recalculations.
• Volume Calculation: The script calculates the highest and lowest prices within the visible bars and iterates through each price level between these extremes. For each price level, it checks if the price has been reached before. If so, it increments the volume count; if not, it initializes the count for that price.
• Volume Aggregation: After determining the volume at each price level, the total volume within the range is calculated.
• Drawing Segments: Finally, if the volume data is set, the script draws segments on the chart representing the volume at each price level, with the segment length proportional to the volume.

This approach provides a visual representation of where the majority of trading activity occurred, which can be useful for identifying support and resistance levels based on volume.