Module:Average change

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local getArgs = require('Module:Arguments').getArgs
local p = {}

function p.main(frame)
	local args = getArgs(frame)
	return p._main(args)
end

-- Main function to calculate average change
function p._main(args)
    local class = args.class
    local omitop = args.omitop
    local params = { args[1], args[2], args[3], args[4], args[5], args[6] }

    -- Filter out nil values and convert to numbers
    local values = {}
    for _, v in ipairs(params) do
        v = tonumber(v)
        if v then
            table.insert(values, v)
        end
    end

    -- Dash (blank) if fewer than 2 valid values
    if #values < 2 then
        return '—'
    end

    -- Calculate changes
    local changes = {}
    for i = 1, #values - 1 do
        if class == "percent" then
            table.insert(changes, ((values[i + 1] - values[i]) / values[i]) * 100)
        else
            table.insert(changes, values[i + 1] - values[i])
        end
    end

    -- Calculate average change
    local sum = 0
    for _, change in ipairs(changes) do
        sum = sum + change
    end

    local avgChange = sum / #changes
    local formattedChange = string.format("%.2f", avgChange)

    -- Omit the operator if specified
    if omitop == "yes" then
        formattedChange = string.gsub(formattedChange, "^%-", "")
    end

    return formattedChange
end

return p