Grant (and Pyro-users),
Thanks for the bug report! You were right, and in fact there were a few
issues with that little bit of code. I've updated CVS to include the
following in pyrobot/robot/device.py:
elif type(item) == types.SliceType:
if item.step:
step = item.step
else:
step = 1
if item.start == None:
if step > 0:
start = 0
else:
start = len(self) - 1
else:
start = item.start
if item.stop == None:
if step > 0:
stop = len(self)
else:
stop = -1
elif item.stop > len(self):
stop = len(self)
else:
stop = item.stop
if start < 0 and step > 0:
start = len(self) + start
if stop < 0 and step > 0:
stop = len(self) + stop
return [self.getSensorValue(p) for p in xrange(start, stop,
step)]
This allows it to act much more similarly to Python's slice behavior,
including:
self.robot.sonar[0][:]
self.robot.sonar[0][:-1]
self.robot.sonar[0][-3:-1]
self.robot.sonar[0][::2]
Let me know if you see anything wrong with this. Thanks again!
-Doug
Grant Braught wrote:
Hi Doug,
We've been working on a summer research project here using Pyro and seem
to have come across a bug. There is an easy work-around so it's not too
big a deal but I thought I'd let you know. It seems that when using
list slices to access a range of sensor values, the value of the sensor
with the maximum index is never included. Here's some sample code that
illustrates the bug:
===
from pyrobot.brain import Brain
class BugBrain(Brain):
def step(self):
rrangea = [s.value for s in self.robot.sonar[0]['all']]
rrangeb = [s.value for s in self.robot.sonar[0][0:16]]
print len(rrangea) # prints 16
print rrangea # prints all 16 sonar values.
print
print len(rrangeb) # prints 15
print rrangeb # prints all but the last sonar value.
print
print
# Create the brain and return it to the Pyrobot program.
def INIT(engine):
return BugBrain('BB', engine)
===
It looks like this is caused by some code in the __getItem__ method in
the Device class.
elif type(item) == types.SliceType:
if item.stop >= len(self): stop = len(self) - 1
else: stop = item.stop
step = 1
if item.step:
step = item.step
return [self.getSensorValue(p) for p in xrange(item.start,
stop, step)]
This seems to cut off the last element when a slice is being used to
access the sensor values.
===
Since the range names work we can just use those with no problem. We
actually discovered this using the bumpers where we wanted to get the
rear bumpers ([s.value for s in self.robot.bumpers[0][5:10]) and then
check each one to see if it was triggered. That list turned out to only
have 4 elements in it, causing out of bounds errors when we checked the
[4]th index.
===
Thanks again for all your hard work in putting the Pyro stuff together
and maintaining it! It is a great tool!
Grant
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