[Stats] index.lua

local SIGMA = function(t)
    local sum = 0
    for i = 1, #t do
        sum = sum + t[i]
    end
    return sum
end

local MEANS = function(t)
    local sigma = {xini = 0, ni = SIGMA(t[1])}
    local p_xini = {}
    for i = 1, #t[1] do
        p_xini[i] = t[1][i]*t[2][i]
    end
    sigma.xini = SIGMA(p_xini)
    return(sigma.xini/sigma.ni)
end

local VARIANCE = function(t)
    local sigma = {ni = SIGMA(t[1]), nixix2 = 0}
    local means_t = MEANS(t)
    local p_nixix2 = {}
    for i = 1, #t[1] do
        p_nixix2[i] = t[1][i]*(t[2][i]-means_t)^2
    end
    sigma.nixix2 = SIGMA(p_nixix2)
    return(sigma.nixix2/sigma.ni)
end

local STANDARD_DEVIATION = function(v)
    return math.sqrt(v)
end

local MEDIAN = function(t)
    local n = #t[1]
    return((n % 2 == 0) and t[2][(n/2)+1] or t[2][(n+1)/2])
end

--! en cours
local QUARTILES = function(t)
    local q = {0, MEDIAN(t), 0}
    return unpack(q)
end

local serie = {
    {4,     20,     43,     100,    200,    250,    190,    113,    50,     19,     6,      5}, -- ni
    {8,     8.1,    8.2,    8.3,    8.4,    8.5,    8.6,    8.7,    8.8,    8.9,    9,      9.1} -- xi
}


print("sommes des lignes du tableau : " .. SIGMA(serie[1]) .. " " .. SIGMA(serie[2]))
print("moyenne : " .. MEANS(serie), "\nvariance : " .. VARIANCE(serie), "\necart type : " .. STANDARD_DEVIATION(VARIANCE(serie)))
print("mediane : " .. MEDIAN(serie))
print("quartiles : ", QUARTILES(serie))