前俩篇博客介绍了
1. 使用Python，networkx对卡勒德胡赛尼三部曲之《群山回唱》人物关系图谱绘制
2. 使用Python，networkx绘制有向层级结构图
3. 使用Python，maplotlib绘制树型有向层级结构图 这篇博客是绘制层级结构图三部曲最后一篇。

1. 效果图

按父子层级结构绘制图形，并标记之间的关联关系，并根据不同标签绘制不同颜色箭头（hello的蓝色箭头，bad的红色箭头，默认绿色箭头），效果图如下：

同样是表达层级结构关系，可以很明显的看出来这比上篇博客使用networkx绘制的层级图要清楚很多，一目了然。

不同箭头样式：

支持的所有箭头及箭头弯曲程度样式如下：

2. 源码

2.1 plotTree.py绘制层级结构及不同样式

# python plotTree.py
# 绘制层级结构图，并根据标签值对树绘制不同颜色


import matplotlib.pyplot as plt

plt.rcParams['backend'] = 'TkAgg'
decisionNode = dict(boxstyle="sawtooth", fc="0.8")
leafNode = dict(boxstyle="round4", fc="0.8")


def getNumLeafs(myTree):
    numLeafs = 0
    firstStr = list(myTree.keys())[0]
    secondDict = myTree[firstStr]
    for key in secondDict.keys():
        if type(secondDict[
                    key]).__name__ == 'dict':  # test to see if the nodes are dictonaires, if not they are leaf nodes
            numLeafs += getNumLeafs(secondDict[key])
        else:
            numLeafs += 1
    return numLeafs


def getTreeDepth(myTree):
    maxDepth = 0
    firstStr = list(myTree.keys())[0]
    secondDict = myTree[firstStr]
    for key in secondDict.keys():
        if type(secondDict[
                    key]).__name__ == 'dict':  # test to see if the nodes are dictonaires, if not they are leaf nodes
            thisDepth = 1 + getTreeDepth(secondDict[key])
        else:
            thisDepth = 1
        if thisDepth > maxDepth: maxDepth = thisDepth
    return maxDepth


def plotNode(nodeTxt, centerPt, parentPt, nodeType, color):
    # 分别表示箭头的样式，俩边距离边框的值，以及箭头线的弯曲程度，箭头的颜色
    arrow_args = dict(arrowstyle="<-", shrinkA=10, shrinkB=10, patchA=None, patchB=None, connectionstyle="arc3,rad=0.3",
                      color=color)
    arrow_args = dict(arrowstyle="<-", shrinkA=10, shrinkB=10, patchA=None, patchB=None, connectionstyle="arc3, rad = 0.",
                      color=color)
    createPlot.ax1.annotate(nodeTxt, xy=parentPt, xycoords='axes fraction',
                            xytext=centerPt, textcoords='axes fraction',
                            va="center", ha="center", bbox=nodeType, arrowprops=arrow_args)


def plotMidText(cntrPt, parentPt, txtString):
    xMid = (parentPt[0] - cntrPt[0]) / 2.0 + cntrPt[0]
    yMid = (parentPt[1] - cntrPt[1]) / 2.0 + cntrPt[1]
    createPlot.ax1.text(xMid, yMid, txtString, va="center", ha="center", rotation=30)


def getArrowColors(parentNode, firstStr, edgeDict):
    key = parentNode + '->' + firstStr
    if not edgeDict.__contains__(key):
        color = 'black'
    elif edgeDict[key].__contains__('hello'):
        color = 'blue'
    elif edgeDict[key].__contains__('bad'):
        color = 'red'
    else:
        color = 'green'
    return color


def getArrowAttrTxt(parentNode, firstStr, edgeDict):
    key = parentNode + '->' + firstStr
    if not edgeDict.__contains__(key):
        return ''
    return edgeDict[key]


def plotTree(myTree, parentPt, parentNode, nodeTxt):
    numLeafs = getNumLeafs(myTree)
    depth = getTreeDepth(myTree)
    firstStr = list(myTree.keys())[0]
    cntrPt = (plotTree.xOff + (1.0 + float(numLeafs)) / 2.0 / plotTree.totalW, plotTree.yOff)
    plotMidText(cntrPt, parentPt, getArrowAttrTxt(parentNode, firstStr, edgeDict))
    plotNode(firstStr, cntrPt, parentPt, decisionNode, getArrowColors(parentNode, firstStr, edgeDict))
    secondDict = myTree[firstStr]
    plotTree.yOff = plotTree.yOff - 1.0 / plotTree.totalD
    for key in secondDict.keys():
        if type(secondDict[key]).__name__ == 'dict':
            print("++++++++++++: ", key, firstStr)
            plotTree(secondDict[key], cntrPt, firstStr, str(key))  # recursion
        else:
            print('----: ', secondDict[key], firstStr, key)
            plotTree.xOff = plotTree.xOff + 1.0 / plotTree.totalW
            plotNode(secondDict[key], (plotTree.xOff, plotTree.yOff), cntrPt, leafNode,
                     getArrowColors(firstStr, secondDict[key], edgeDict))
            plotMidText((plotTree.xOff, plotTree.yOff), cntrPt, getArrowAttrTxt(firstStr, secondDict[key], edgeDict))
    plotTree.yOff = plotTree.yOff + 1.0 / plotTree.totalD


def createPlot(inTree):
    fig = plt.figure(1, facecolor='white')
    fig.clf()
    axprops = dict(xticks=[], yticks=[])
    createPlot.ax1 = plt.subplot(111, frameon=False, **axprops)  # no ticks
    # createPlot.ax1 = plt.subplot(111, frameon=False) #ticks for demo puropses
    plotTree.totalW = float(getNumLeafs(inTree))
    plotTree.totalD = float(getTreeDepth(inTree))
    plotTree.xOff = -0.5 / plotTree.totalW;
    plotTree.yOff = 1.0;
    plotTree(inTree, (0.5, 1.0), 'A', '')
    plt.show()


def retrieveTree(i):
    listOfTrees = [{'no surfacing': {0: 'no', 1: {'flippers': {0: 'no', 1: 'yes'}}}},
                   {'no surfacing': {0: 'no', 1: {'flippers': {0: {'head': {0: 'no', 1: 'yes'}}, 1: 'no'}}}}
                   ]
    return listOfTrees[i]


def getTree(treeDict, nood):
    retrieveTree = {}
    for i, val in enumerate(treeDict[nood]):
        print(i, nood, val)
        if (treeDict.__contains__(val)):
            subTree = {}
            subTree[val] = getTree(treeDict, val)
            retrieveTree[i] = subTree
        else:
            retrieveTree[i] = val
    return retrieveTree


def getRetrieveTree():
    treeDict = {}
    edgeDict = {}
    with open("res/tree.txt", 'r', encoding='utf-8', errors='ignore') as f:
        data = f.readlines()

        for i, line in enumerate(data):
            parentNode = line.split(",")[0]
            childNode = line.split(",")[1]
            edgeDict[parentNode + "->" + childNode] = line.split(",")[2]
            # print(parentNode, childNode)
            if not treeDict.__contains__(parentNode):
                treeDict[parentNode] = set()
            treeDict[parentNode].add(childNode)

    print(treeDict)
    treeDict0 = {}
    treeDict0['A'] = getTree(treeDict, 'A')

    # print(treeDict0)
    return (treeDict0, edgeDict)


# treeDemo = retrieveTree(1)
# print(treeDemo)
# createPlot(treeDemo)
(treeDict, edgeDict) = getRetrieveTree()
print(treeDict)
createPlot(treeDict)

2.2 plotArrow.py 支持的所有箭头样式

# python plotArrow.py
from matplotlib import pyplot as plt

print(plt.rcParams['backend'])  # module://backend_interagg
plt.rcParams['backend'] = 'TkAgg'


def demo_con_style(ax, connectionstyle):
    x1, y1 = 0.3, 0.2
    x2, y2 = 0.8, 0.6

    ax.plot([x1, x2], [y1, y2], ".")
    ax.annotate("", xy=(x1, y1), xycoords='data',
                xytext=(x2, y2), textcoords='data',
                arrowprops=dict(arrowstyle="->", color="0.5",
                                shrinkA=5, shrinkB=5,
                                patchA=None, patchB=None,
                                connectionstyle=connectionstyle,
                                ),
                )

    ax.text(.05, .95, connectionstyle.replace(",", ",\n"),
            transform=ax.transAxes, ha="left", va="top")


fig, axs = plt.subplots(3, 5, figsize=(8, 4.8))
demo_con_style(axs[0, 0], "angle3, angleA = 90, angleB = 0")
demo_con_style(axs[1, 0], "angle3, angleA = 0, angleB = 90")
demo_con_style(axs[0, 1], "arc3, rad = 0.")
demo_con_style(axs[1, 1], "arc3, rad = 0.3")
demo_con_style(axs[2, 1], "arc3, rad = -0.3")
demo_con_style(axs[0, 2], "angle, angleA = -90, angleB = 180, rad = 0")
demo_con_style(axs[1, 2], "angle, angleA = -90, angleB = 180, rad = 5")
demo_con_style(axs[2, 2], "angle, angleA = -90, angleB = 10, rad = 5")
demo_con_style(axs[0, 3], "arc, angleA = -90, angleB = 0, armA = 30, armB = 30, rad = 0")
demo_con_style(axs[1, 3], "arc, angleA = -90, angleB = 0, armA = 30, armB = 30, rad = 5")
demo_con_style(axs[2, 3], "arc, angleA = -90, angleB = 0, armA = 0, armB = 40, rad = 0")
demo_con_style(axs[0, 4], "bar, fraction = 0.3")
demo_con_style(axs[1, 4], "bar, fraction = -0.3")
demo_con_style(axs[2, 4], "bar, angle = 180, fraction = -0.2")

for ax in axs.flat:
    ax.set(xlim=(0, 1), ylim=(0, 1), xticks=[], yticks=[], aspect=1)
fig.tight_layout(pad=0.2)

plt.show()

参考

• https://blog.csdn.net/weixin_42915773/article/details/111566041
• https://blog.csdn.net/TQCAI666/article/details/103689182