Matplotlib实战之平行坐标系绘制详解

fp = "d:/share/A0M06.csv"
df = pd.read_csv(fp)
df

import os
files = {
    "教师数": "A0M06.csv",
    "招生数": "A0M07.csv",
    "在校学生数": "A0M08.csv",
    "毕业学生数": "A0M09.csv",
}
data_dir = "d:/share"
data = pd.DataFrame()
for key in files:
    fp = os.path.join(data_dir, files[key])
    df = pd.read_csv(fp)
    df_filter = pd.DataFrame(
        [[
            key,
            df.loc[225, "value"],
            df.loc[135, "value"],
            df.loc[90, "value"],
            df.loc[270, "value"],
        ]],
        columns=["name", "小学", "初中", "高中", "特殊教育"],
    )
    data = pd.concat([data, df_filter])
data

import matplotlib.pyplot as plt
from matplotlib.path import Path
import matplotlib.patches as patches
import numpy as np
xnames = data.loc[:, "name"]
ynames = ["小学", "初中", "高中", "特殊教育"]
ys = np.array(data.iloc[:, 1:].values.tolist())
ymins = ys.min(axis=0)
ymaxs = ys.max(axis=0)
dys = ymaxs - ymins
ymins -= dys * 0.05  # Y轴的上下限增加 5% 的冗余
ymaxs += dys * 0.05
#每个坐标系的上下限不一样，调整显示方式
zs = np.zeros_like(ys)
zs[:, 0] = ys[:, 0]
zs[:, 1:] = (ys[:, 1:] - ymins[1:]) / dys[1:] * dys[0] + ymins[0]
fig, host = plt.subplots(figsize=(10, 4))
axes = [host] + [host.twinx() for i in range(ys.shape[1] - 1)]
for i, ax in enumerate(axes):
    ax.set_ylim(ymins[i], ymaxs[i])
    ax.spines["top"].set_visible(False)
    ax.spines["bottom"].set_visible(False)
    if ax != host:
        ax.spines["left"].set_visible(False)
        ax.yaxis.set_ticks_position("right")
        ax.spines["right"].set_position(("axes", i / (ys.shape[1] - 1)))
host.set_xlim(0, ys.shape[1] - 1)
host.set_xticks(range(ys.shape[1]))
host.set_xticklabels(ynames, fontsize=14)
host.tick_params(axis="x", which="major", pad=7)
host.spines["right"].set_visible(False)
host.xaxis.tick_top()
host.set_title("各类学校的师生数目比较", fontsize=18, pad=12)
colors = plt.cm.Set1.colors
legend_handles = [None for _ in xnames]
for j in range(ys.shape[0]):
    verts = list(
        zip(
            [x for x in np.linspace(0, len(ys) - 1, len(ys) * 3 - 2, endpoint=True)],
            np.repeat(zs[j, :], 3)[1:-1],
        )
    )
    codes = [Path.MOVETO] + [Path.CURVE4 for _ in range(len(verts) - 1)]
    path = Path(verts, codes)
    patch = patches.PathPatch(
        path, facecolor="none", lw=2, alpha=0.7, edgecolor=colors[j]
    )
    legend_handles[j] = patch
    host.add_patch(patch)
host.legend(
    xnames,
    loc="lower center",
    bbox_to_anchor=(0.5, -0.18),
    ncol=len(xnames),
    fancybox=True,
    shadow=True,
)
plt.tight_layout()
plt.show()