AttributeError: 'float' object has no attribute 'get_coords' - python-3.x

Question

I'm learning Python from this lecture: Lec 19 | MIT 6.00 Introduction to Computer Science and Programming. I'm using Python 3.6.2, lecture example runs on Python 2.x. Whats the proper way to set values of x and y in function ans_quest?
x, y = loc_list[-1].get_coords()
Can this method be called like this? This was the example in the lecture.
Full code:
import math, random, pylab, copy
class Location(object):
def __init__(self, x, y):
self.x = float(x)
self.y = float(y)
def move(self, xc, yc):
return Location(self.x+float(xc), self.y+float(yc))
def get_coords(self):
return self.x, self.y
def get_dist(self, other):
ox, oy = other.get_coords()
x_dist = self.x - ox
y_dist = self.y - oy
return math.sqrt(x_dist**2 + y_dist**2)
class Compass_Pt(object):
possibles = ('N', 'S', 'E', 'W')
def __init__(self, pt):
if pt in self.possibles: self.pt = pt
else: raise ValueError('in Compass_Pt.__init__')
def move(self, dist):
if self.pt == 'N': return (0, dist)
elif self.pt == 'S': return (0, -dist)
elif self.pt == 'E': return (dist, 0)
elif self.pt == 'W': return (-dist, 0)
else: raise ValueError('in Compass_Pt.move')
class Field(object):
''' Cartesian plane where object will be located '''
def __init__(self, drunk, loc):
self.drunk = drunk
self.loc = loc
def move(self, cp, dist):
old_loc = self.loc
xc, yc = cp.move(dist)
self.loc = old_loc.move(xc, yc)
def get_loc(self):
return self.loc
def get_drunk(self):
return self.drunk
class Drunk(object):
''' Point itself '''
def __init__(self, name):
self.name = name
def move(self, field, cp, dist = 1):
if field.get_drunk().name != self.name:
raise ValueError('Drunk.move called with drunk not in the field')
for i in range(dist):
field.move(cp, 1)
class Usual_Drunk(Drunk):
def move(self, field, dist = 1):
''' Drunk.move superclass method override. Sends additional cp attribute.'''
cp = random.choice(Compass_Pt.possibles)
Drunk.move(self, field, Compass_Pt(cp), dist)
class Cold_Drunk(Drunk):
def move(self, field, dist = 1):
cp = random.choice(Compass_Pt.possibles)
if cp == 'S':
Drunk.move(self, field, Compass_Pt(cp), 2*dist)
else:
Drunk.move(self, field, Compass_Pt(cp), dist)
class EW_Drunk(Drunk):
def move(self, field, time = 1):
cp = random.choice(Compass_Pt.possibles)
while cp != 'E' and cp != 'W':
cp = random.choice(Compass_Pt.possibles)
Drunk.move(self, field, Compass_Pt(cp), time)
def perform_trial(time, f):
start = f.get_loc()
distances = [0,0]
for t in range(1, time + 1):
f.get_drunk().move(f)
new_loc = f.get_loc()
distance = new_loc.get_dist(start)
distances.append(distance)
return distances
def perform_sim(time, num_trials, drunk_type):
dist_lists = []
loc_lists = []
for trial in range(num_trials):
d = drunk_type('Drunk' + str(trial))
f = Field(d, Location(0, 0))
distances = perform_trial(time, f)
locs = copy.deepcopy(distances)
dist_lists.append(distances)
loc_lists.append(locs)
return dist_lists, loc_lists
def ans_quest(max_time, num_trials, drunk_type, title):
dist_lists, loc_lists = perform_sim(max_time, num_trials, drunk_type)
means = []
for t in range(max_time + 1):
tot = 0.0
for dist_l in dist_lists:
tot += dist_l[t]
means.append(tot/len(dist_lists))
pylab.figure()
pylab.plot(means)
pylab.ylabel('distance')
pylab.xlabel('time')
pylab.title('{} Ave. Distance'.format(title))
lastX = []
lastY = []
for loc_list in loc_lists:
x, y = loc_list[-1].get_coords()
lastX.append(x)
lastY.append(y)
pylab.figure()
pylab.scatter(lastX, lastY)
pylab.ylabel('NW Distance')
pylab.title('{} Final location'.format(title))
pylab.figure()
pylab.hist(lastX)
pylab.xlabel('EW Value')
pylab.ylabel('Number of Trials')
pylab.title('{} Distribution of Final EW Values'.format(title))
num_steps = 50
num_trials = 10
ans_quest(num_steps, num_trials, Usual_Drunk, 'Usual Drunk ' + str(num_trials) + ' Trials')
ans_quest(num_steps, num_trials, Cold_Drunk, 'Cold Drunk ' + str(num_trials) + ' Trials')
ans_quest(num_steps, num_trials, EW_Drunk, 'EW Drunk ' + str(num_trials) + ' Trials')
pylab.show()
Error:
Traceback (most recent call last):
File "/home/tihe/Documents/CODING/Project Home/Python/biased_random_walks.py", line 194, in <module>
ans_quest(num_steps, num_trials, Usual_Drunk, 'Usual Drunk ' + str(num_trials) + ' Trials')
File "/home/tihe/Documents/CODING/Project Home/Python/biased_random_walks.py", line 175, in ans_quest
x, y = loc_list[-1].get_coords()
AttributeError: 'float' object has no attribute 'get_coords'

Answer 1

This method could be called like this if you had a list of Location objects. The error is because the loc_list is populated with distances and not Location objects. That happens in function perform_sim when instead of geting the location you are making a deep copy of distance.
Perhaps you could try something like this:
def perform_trial(time, f):
start = f.get_loc()
distances = [0,0]
locations = []
for t in range(1, time + 1):
f.get_drunk().move(f)
new_loc = f.get_loc()
locations.append(new_loc)
distance = new_loc.get_dist(start)
distances.append(distance)
return distances, locations
def perform_sim(time, num_trials, drunk_type):
dist_lists = []
loc_lists = []
for trial in range(num_trials):
d = drunk_type('Drunk' + str(trial))
f = Field(d, Location(0, 0))
distances, locations = perform_trial(time, f)
dist_lists.append(distances)
loc_lists.append(locations)
return dist_lists, loc_lists
I hope that helped you out.