# -*- coding: utf-8 -*-
import numpy as np
import matplotlib.pyplot as plt
from scipy.optimize import curve_fit

# ===========================================================
# フィッティングのクラス
# ===========================================================
class FITTING(object):
    # -------------------------------------------------------
    # コンストラクター
    # -------------------------------------------------------
    def __init__(self, function, x, y):
        self.f = function
        self.x = x
        self.y = y


    # -------------------------------------------------------
    # フィッティングの実行
    # -------------------------------------------------------
    def do_fitting(self):
        self.popt, self.pcov = curve_fit(self.f, self.x, self.y)

        print('a: {0:e}\nb: {1:e}\nc: {2:e}'.\
              format(self.popt[0], self.popt[1], self.popt[2]))


    # -------------------------------------------------------
    # フィッティング結果のプロット
    # -------------------------------------------------------
    def plot(self, Nx=65):
        xmin, xmax = min(self.x), max(self.x)
        xp = np.linspace(xmin, xmax, Nx)
        fig = plt.figure()
        plot = fig.add_subplot(1,1,1)
        plot.set_xlabel("x", fontsize=12, fontname='serif')
        plot.set_ylabel("y", fontsize=12, fontname='serif')
        plot.tick_params(axis='both', length=10, which='major')
        plot.tick_params(axis='both', length=5,  which='minor')
        plot.set_xlim(xmin, xmax)
        plot.set_ylim([-1.2,1.2])
        plot.minorticks_on()
        plot.plot(xp, self.f(xp, *self.popt), 'b-')
        plot.plot(x, y, 'ro', markersize=10)
        fig.tight_layout()
        plt.show()
        fig.savefig('result.pdf', orientation='portrait', \
                         transparent=False, bbox_inches=None, frameon=None)
        fig.clf()


# -------------------------------------------------------
# データをフィッティングする関数
# -------------------------------------------------------
def fit_func(x, a, b, c):
    return a*np.sin(x)*np.exp(-b*x)+c
    

# -------------------------------------------------------
# メイン関数
# -------------------------------------------------------
if __name__ == "__main__":

    x = np.linspace(0, 6*np.pi, 32)
    noise = 0.05*np.random.normal(size=x.size)
    y = np.sin(x)*np.exp(-x/5) + noise

    fit = FITTING(fit_func, x, y)
    fit.do_fitting()
    fit.plot(Nx=257)