import numpy as np
import matplotlib.pyplot as plt


# f(x) = 1/(1+e(-z))


def sigmoid(x, min_value=0.3, max_value=5, right_offset=5, span=10):
    """
    min_value: y最小值
    max_value: y最大值
    right_offset: 曲线右移
    span: y从接近最小到接近最大时,自变量x的跨度
    """
    # 右移
    x -= right_offset
    # 缩放
    x *= 10 / span
    # 振幅
    return (max_value - min_value) / (1 + np.exp(-x)) + min_value


def test():
    plt.rcParams["font.family"] = "SimHei"
    plt.rcParams["axes.unicode_minus"] = False
    plt.rcParams["font.size"] = 12

    z = np.linspace(-10, 10, 200)
    plt.plot(z, sigmoid(z))

    plt.axvline(x=0, ls="--", c="k")
    plt.axhline(ls=":", c="k")
    plt.axhline(y=0.5, ls=":", c="k")
    plt.axhline(y=1, ls=":", c="k")
    plt.xlabel("z值")
    plt.ylabel("sigmoid(z)值")


if __name__ == "__main__":
    test()
    # for i in range(20):
    #     x = i + 1
    #     print(x, sigmoid(x, span=10))

# cd grpc
# mkdir -p cmake/build
# pushd cmake/build
# cmake -DgRPC_INSTALL=ON \
#     -DgRPC_BUILD_TESTS=OFF \
#     ../..
# make -j 4
# make install
# popd