每个句柄具有不同数量和颜色标记的 Matplotlib 图例
Matplotlib Legend with Different Number and Color of Markers per Handle
鉴于以下情况：
import pandas as pd
import matplotlib.pyplot as plt
d=pd.DataFrame({'category':['a','a','a','b','b','b'],
'year':[1,2,1,2,1,2],
'x':[2,4,5,1,2,3],
'y':[1,2,3,2,4,6],
'clr':['grey','green','grey','blue','grey','orange']})
d
category clr x y year
0 a grey 2 1 1
1 a green 4 2 2
2 a grey 5 3 1
3 b blue 1 2 2
4 b grey 2 4 1
5 b orange 3 6 2
和
for i in np.arange(len(d)):
plt.plot(d.x[i],d.y[i],marker='o',linestyle='none',markerfacecolor=d.clr[i],
markeredgecolor='none',markersize=15)
#clean up axes
plt.tick_params(axis='x',which='both',bottom='off',top='off',color='none',labelcolor='none')
plt.tick_params(axis='y',which='both',left='off',right='off',color='none',labelcolor='none')
lgnd=plt.legend(['Year 1','Year 2'],
numpoints=1,
loc=0,
ncol=1,
fontsize=10,
frameon=False)
lgnd.legendHandles[0]._legmarker.set_markersize(15)
lgnd.legendHandles[1]._legmarker.set_markersize(15)
我希望图例中第 1 年的标记有一个灰点（目前如此），但第 2 年的标记有一个点代表每种不同的颜色（在本例中为橙色、蓝色, 和绿点都在同一行上，此时顺序无关紧要，连续）。
像这样：
我尝试了以下方法，但无济于事：
lgnd.legendHandles[1]._legmarker.set_numpoints(len(d.clr.unique()))
lgnd.legendHandles[1]._legmarker.set_markeredgecolor(d.clr)
提前致谢！
我很高兴为您的问题找出解决方案（并在此过程中学习了一些新技巧）。本质上，您可以创建自己的图例处理程序对象以将所有颜色映射到年份。可以通过制作任何具有函数 legend_artist(self, legend, orig_handle, fontsize, handlebox) 的对象来制作自定义图例处理程序。可以在 this page 的 "Implementing custom handler" 部分中找到此工作原理的详细信息。我把代码里的解释都注释掉了，因为文字太多，没有代码可以展示。
示例代码：
import numpy as np
import pandas as pd
import matplotlib.pyplot as plt
import pdb
import matplotlib.patches as mpatches
class MyLegendHandler(object):
def __init__(self,color):
self.color = color
def legend_artist(self, legend, orig_handle, fontsize, handlebox):
x0, y0 = handlebox.xdescent, handlebox.ydescent #offset of the lower left corner
width, height = handlebox.width, handlebox.height #width, height bound box of legend, for now, it is the dimension of each circle legend
#NOTE: to be practicle, let's just set radius = height as if width != height, it's an ellipse
#NOTE: these will latter on be changed internally to accomdate adding text
handlebox.width += len(self.color)*height # reset width of handlebox to accomodate multiple legends
for i in range(len(self.color)): #loop through all colors
#for each color, draw a circle of that color
#NOTE: play around here to align the legends right rather than left :)
center = [0.5*(i + 1) * width - 0.5*x0, 0.5 * height - 0.5 * y0]
patch = mpatches.Ellipse(center, height, height, facecolor=self.color[i],
edgecolor=None, hatch=None, transform=handlebox.get_transform())
handlebox.add_artist(patch)
return patch
###################################
d=pd.DataFrame({'category':['a','a','a','b','b','b'],
'year':[1,2,1,2,1,2],
'x':[2,4,5,1,2,3],
'y':[1,2,3,2,4,6],
'clr':['grey','green','grey','blue','grey','orange']})
unique_year_elements = []
years_seen = []
tmp = None
my_map = {}
for i in np.arange(len(d)):
tmp, = plt.plot(d.x[i],d.y[i],marker='o',linestyle='none',markerfacecolor=d.clr[i],
markeredgecolor='none',markersize=15)
#collect the plot elements that are of unique years-- 1 year might have several plot element, we only need 1
if not (d.year[i] in years_seen):
years_seen.append(d.year[i])
unique_year_elements.append(tmp)
#build handler_map for plt.legend to map elements to its legend handler object
for i in np.arange(len(years_seen)):
color_list = d.loc[d['year'] == years_seen[i]].clr.unique().tolist()
#pdb.set_trace()
my_map[unique_year_elements[i]] = MyLegendHandler(color_list)
#creating the legend object
plt.legend( unique_year_elements, ["Year "+str(y) for y in years_seen],
handler_map=my_map)
#clean up axes
plt.tick_params(axis='x',which='both',bottom='off',top='off',color='none',labelcolor='none')
plt.tick_params(axis='y',which='both',left='off',right='off',color='none',labelcolor='none')
plt.show()
示例输出：
另一种对我有用的方法是绘制圆圈（椭圆 - 看看为什么 here）和文本：
import matplotlib.patches as mpatches
#Set ellipse dimension coordinates
xmax_el=xmax/30
ymax_el=ymax/28
#Set ellipse y-location coordinates
yloc1=max(ind)+2.5
yloc2=max(ind)+1.75
#Create first circle in grey as just one grey circle is needed:
circlex=mpatches.Ellipse((pmax-.2*pmax,yloc1), xmax_el, ymax_el ,alpha=0.5,clip_on=False\
,edgecolor='grey',linewidth=2,facecolor='none')
#Start a list of patches (circles), with the grey one being the first:
patches=[circlex]
clrs=['g','r','b']
#Populate a list of circles, one for each unique color for patch names
circles=[]
for i in np.arange(len(clrs)):
circles.append('circle'+str(i))
#This list is for multiplying by the x-position dimension to space out the colored bubbles:
clrnum=np.arange(len(clrs))
#Reverse the order of colors so they plot in order on the chart (if clrs was based on real data that is being plotted)
clrs2=clrs[::-1]
#Iterate through the color, circle, and circle number lists, create patches, and plot.
for i,j,k in zip(clrs2,circles,clrnum):
j=mpatches.Ellipse((pmax-(.2+k*0.05)*pmax,yloc2),xmax_el,ymax_el,alpha=0.5,clip_on=False,edgecolor=i,linewidth=2,facecolor='none')
patches.append(j)
for i in patches:
ax.add_artist(i)
#Add text:
ax.text(pmax-.15*pmax,yloc1,'2015 Plan Offering',color='grey',ha='left',va='center')
ax.text(pmax-.15*pmax,yloc2,'2016 Plan Offering',color='grey',ha='left',va='center')
结果：
鉴于以下情况：
import pandas as pd
import matplotlib.pyplot as plt
d=pd.DataFrame({'category':['a','a','a','b','b','b'],
'year':[1,2,1,2,1,2],
'x':[2,4,5,1,2,3],
'y':[1,2,3,2,4,6],
'clr':['grey','green','grey','blue','grey','orange']})
d
category clr x y year
0 a grey 2 1 1
1 a green 4 2 2
2 a grey 5 3 1
3 b blue 1 2 2
4 b grey 2 4 1
5 b orange 3 6 2
和
for i in np.arange(len(d)):
plt.plot(d.x[i],d.y[i],marker='o',linestyle='none',markerfacecolor=d.clr[i],
markeredgecolor='none',markersize=15)
#clean up axes
plt.tick_params(axis='x',which='both',bottom='off',top='off',color='none',labelcolor='none')
plt.tick_params(axis='y',which='both',left='off',right='off',color='none',labelcolor='none')
lgnd=plt.legend(['Year 1','Year 2'],
numpoints=1,
loc=0,
ncol=1,
fontsize=10,
frameon=False)
lgnd.legendHandles[0]._legmarker.set_markersize(15)
lgnd.legendHandles[1]._legmarker.set_markersize(15)
我希望图例中第 1 年的标记有一个灰点（目前如此），但第 2 年的标记有一个点代表每种不同的颜色（在本例中为橙色、蓝色, 和绿点都在同一行上，此时顺序无关紧要，连续）。 像这样：
我尝试了以下方法，但无济于事：
lgnd.legendHandles[1]._legmarker.set_numpoints(len(d.clr.unique()))
lgnd.legendHandles[1]._legmarker.set_markeredgecolor(d.clr)
提前致谢！
我很高兴为您的问题找出解决方案（并在此过程中学习了一些新技巧）。本质上，您可以创建自己的图例处理程序对象以将所有颜色映射到年份。可以通过制作任何具有函数 legend_artist(self, legend, orig_handle, fontsize, handlebox) 的对象来制作自定义图例处理程序。可以在 this page 的 "Implementing custom handler" 部分中找到此工作原理的详细信息。我把代码里的解释都注释掉了，因为文字太多，没有代码可以展示。
示例代码：
import numpy as np
import pandas as pd
import matplotlib.pyplot as plt
import pdb
import matplotlib.patches as mpatches
class MyLegendHandler(object):
def __init__(self,color):
self.color = color
def legend_artist(self, legend, orig_handle, fontsize, handlebox):
x0, y0 = handlebox.xdescent, handlebox.ydescent #offset of the lower left corner
width, height = handlebox.width, handlebox.height #width, height bound box of legend, for now, it is the dimension of each circle legend
#NOTE: to be practicle, let's just set radius = height as if width != height, it's an ellipse
#NOTE: these will latter on be changed internally to accomdate adding text
handlebox.width += len(self.color)*height # reset width of handlebox to accomodate multiple legends
for i in range(len(self.color)): #loop through all colors
#for each color, draw a circle of that color
#NOTE: play around here to align the legends right rather than left :)
center = [0.5*(i + 1) * width - 0.5*x0, 0.5 * height - 0.5 * y0]
patch = mpatches.Ellipse(center, height, height, facecolor=self.color[i],
edgecolor=None, hatch=None, transform=handlebox.get_transform())
handlebox.add_artist(patch)
return patch
###################################
d=pd.DataFrame({'category':['a','a','a','b','b','b'],
'year':[1,2,1,2,1,2],
'x':[2,4,5,1,2,3],
'y':[1,2,3,2,4,6],
'clr':['grey','green','grey','blue','grey','orange']})
unique_year_elements = []
years_seen = []
tmp = None
my_map = {}
for i in np.arange(len(d)):
tmp, = plt.plot(d.x[i],d.y[i],marker='o',linestyle='none',markerfacecolor=d.clr[i],
markeredgecolor='none',markersize=15)
#collect the plot elements that are of unique years-- 1 year might have several plot element, we only need 1
if not (d.year[i] in years_seen):
years_seen.append(d.year[i])
unique_year_elements.append(tmp)
#build handler_map for plt.legend to map elements to its legend handler object
for i in np.arange(len(years_seen)):
color_list = d.loc[d['year'] == years_seen[i]].clr.unique().tolist()
#pdb.set_trace()
my_map[unique_year_elements[i]] = MyLegendHandler(color_list)
#creating the legend object
plt.legend( unique_year_elements, ["Year "+str(y) for y in years_seen],
handler_map=my_map)
#clean up axes
plt.tick_params(axis='x',which='both',bottom='off',top='off',color='none',labelcolor='none')
plt.tick_params(axis='y',which='both',left='off',right='off',color='none',labelcolor='none')
plt.show()
示例输出：
另一种对我有用的方法是绘制圆圈（椭圆 - 看看为什么 here）和文本：
import matplotlib.patches as mpatches
#Set ellipse dimension coordinates
xmax_el=xmax/30
ymax_el=ymax/28
#Set ellipse y-location coordinates
yloc1=max(ind)+2.5
yloc2=max(ind)+1.75
#Create first circle in grey as just one grey circle is needed:
circlex=mpatches.Ellipse((pmax-.2*pmax,yloc1), xmax_el, ymax_el ,alpha=0.5,clip_on=False\
,edgecolor='grey',linewidth=2,facecolor='none')
#Start a list of patches (circles), with the grey one being the first:
patches=[circlex]
clrs=['g','r','b']
#Populate a list of circles, one for each unique color for patch names
circles=[]
for i in np.arange(len(clrs)):
circles.append('circle'+str(i))
#This list is for multiplying by the x-position dimension to space out the colored bubbles:
clrnum=np.arange(len(clrs))
#Reverse the order of colors so they plot in order on the chart (if clrs was based on real data that is being plotted)
clrs2=clrs[::-1]
#Iterate through the color, circle, and circle number lists, create patches, and plot.
for i,j,k in zip(clrs2,circles,clrnum):
j=mpatches.Ellipse((pmax-(.2+k*0.05)*pmax,yloc2),xmax_el,ymax_el,alpha=0.5,clip_on=False,edgecolor=i,linewidth=2,facecolor='none')
patches.append(j)
for i in patches:
ax.add_artist(i)
#Add text:
ax.text(pmax-.15*pmax,yloc1,'2015 Plan Offering',color='grey',ha='left',va='center')
ax.text(pmax-.15*pmax,yloc2,'2016 Plan Offering',color='grey',ha='left',va='center')
结果：