matplotlib python 列表全面吗？

如何解决matplotlib python 列表全面吗？

我想做一个简单的图表来显示每天所有约会的总利润。结果显示类似的东西

这绝对是不对的。 我知道这个问题在我的 views.py 列表中很全面，但不知道如何解决它.. 任何帮助表示赞赏

models.py

class Service(models.Model):
  service_name = models.CharField(max_length=50)
  service_price = models.DecimalField(max_digits=8,decimal_places=2)
  physician = models.ForeignKey('Physician',on_delete=models.CASCADE)

  def __str__(self):
        return self.service_name

class Appointment(models.Model):
  appointment_date = models.DateField(null=True)
  appointment_time = models.TimeField(null=True)
  patient = models.ForeignKey('Patient',on_delete=models.CASCADE)
  reseptionist = models.ForeignKey('Reseptionist',on_delete=models.SET_NULL,blank=True,null=True)
  service = models.ForeignKey('Service',on_delete=models.CASCADE)
  physician = models.ForeignKey('Physician',on_delete=models.CASCADE)

plots.py

import matplotlib as mpl
mpl.use('Agg')

import matplotlib.pyplot as plt
import base64
from io import BytesIO

def get_graph():
  buffer = BytesIO()
  plt.savefig(buffer,format="png")
  buffer.seek(0)
  img = buffer.getvalue()
  g = base64.b64encode(img)
  g = g.decode("utf-8")
  buffer.close()
  return g


def line_plot(x,y):
  plt.figure(figsize=(4,4)) 
  plt.plot(x,y)
  return get_graph()

views.py

from .plots import line_plot
def index(request): 
    prices = Appointment.objects.all()
    revenue = [x.service.service_price for x in prices]
    
    day = [x.appointment_date for x in prices ]
    
    c = pie_plot(revenue,day)
    
    context = {'chart': c }

    return render(request,'index.html',context)