How do I solve a NoneType Error when programming a robot to move?-CodePudding

I'm trying to get a robot to move from one coordinate to a target coordinate to "collect a pizza" then move with the pizz to a new set of coordinates however the following NonType Eroor comes up and i dont know what this means. here is my move code:

def move(self):
    for c in [0,1]:
      if (self.coordinates[c] < self.target[c]):
        if ((self.target[c] - self.coordinates[c]) < self.max[c]):
          self.velocity[c] = (self.target[c] - self.coordinates[c])
        else: 
          self.velocity[c] = self.max[c]
      elif (self.coordinates[c] > self.target[c]):
        if ((self.coordinates - self.target[c]) < self.max[c]):
          self.velocity[c] = -(self.coordinates[c] - self.target[c])
        else: 
          self.velocity[c] = -self.max[c]
      else:
        self.velocity[c] = 0
      self.coordinates[c]  = self.velocity[c]

and here is the error message:

TypeError                                 Traceback (most recent call last)
<ipython-input-140-00c07d25f390> in <module>()
     33       robot.activity = 'idle'
     34 
---> 35   robot.move()
     36   ecosystem.update()
     37   print(ecosystem.hour)

<ipython-input-136-c31d02f30645> in move(self)
     36   def move(self):
     37     for c in [0,1]:
---> 38       if (self.coordinates[c] < self.target[c]):
     39         if ((self.target[c] - self.coordinates[c]) < self.max[c]):
     40           self.velocity[c] = (self.target[c] - self.coordinates[c])

TypeError: 'NoneType' object is not subscriptable

this is the robot code

class Robot: 
  model = 'robot1'
  def __init__(self): 
    self.coordinates = [1,2,0]           
    self.kind = 'Robot'
    self.max = [1,1,0]
    self.velocity = [1,1,0]
    self.status = 'on'
    self.name = 'robotJL'
    self.activity = 'idle'
    self.target = None
    self.age = 0
    self.serviced = 0
    self.soc = 600
    self.capacity = 600
    self.service = 0
    self.size = 500
    self.damage = 0
    self.color = 'green'
    self.shape = 'triangle'
    self.on_arena = 0
    self.service = 0
    self.weight = 50
    self.payload = 100
    self.cargo = None
    self.distance = 0
    self.energy = 0

CodePudding user response：

I suppose, one of the properties of your robot object (coordinates or target) is None, you should check it.

CodePudding user response：

It means that target coordinates or present coordinates contain None value because of that it is not allowing you to use either self.coordinates[c] or self.target[c]. Printing both the values out will give you clear understanding.