How to access the key values in a nested python dictionary with variables?

Question

I am cleaning up some ROS robot code using the method in this QA. This is not ROS related.

Here is the original code:

 data = []
 data.append(sensor[thermo].data.thermo)
 data.append(sensor[imu].data.imu.x)
 data.append(sensor[imu].data.imu.rotation.x)

Now I have a list of tuples containing all the topics so I can loop around:

topics = [('thermo', 'thermo'),
          ('imu', 'imu.x')
          ('imu', 'imu.rotation.x')]

and:

for sensor, topic in topics:
    data.append(getattr[sensor].data, topic)

This works for thermo, but not for imu, and I am getting the following error:

AttributeError: 'imu' object has no attribute 'x'

How can I fix the getattr statement to achieve the goal here?

If the depth is fixed, you can combine getattr : ...getattr(getattr(sensor[thermo], "att1", None), "attr2", None)... — machine424
– machine424, Commented May 3, 2019 at 21:56
Or you can use reduce from functools: reduce(getattr, "att1.att2.att3".split('.'), sensor[imu]) I think the question is duplicated : stackoverflow.com/questions/3279082/… — machine424
– machine424, Commented May 3, 2019 at 22:03
@machine424 If you think this question is a duplicate of another post, flag it as such. Also, OP, your Q&A link is broken, so you should update it to the correct URL. — Mihai Chelaru
– Mihai Chelaru, Commented May 4, 2019 at 0:15

machine424 · Accepted Answer · 2019-05-22 12:58:04Z

1

The function reduce of functools can be used:

reduce(getattr, "att1.att2.att3".split('.'), sensor[imu])

answered May 22, 2019 at 12:58

machine424

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