CODEWITHSUNDEEP
pythonnumpy
Kuo-Hsien Chang
Kuo-Hsien Chang

Reputation: 935

How to average several readings in python?

A sensor generates an reading every one second for five seconds. I was trying to use the function np.mean to calculate the average of five sensor readings (i.e., sensor1_t1 to sensor1_t5), however it doesn't work.

Can you please help me on this?

Thanks.

sensor1_t1 = BridgeValue(0) * 274.0 - 2.1
sleep(1)
sensor1_t2 = BridgeValue(0) * 274.0 - 2.1
sleep(1)
sensor1_t3 = BridgeValue(0) * 274.0 - 2.1
sleep(1)
sensor1_t4 = BridgeValue(0) * 274.0 - 2.1
sleep(1)
sensor1_t5 = BridgeValue(0) * 274.0 - 2.1
sleep(1)

# my code - not working
#avg_sensor1 = np.mean(sensor1_t1, sensor1_t2, sensor1_t3, sensor1_t4, sensor1_t5)

Upvotes: 0

Views: 417

Answers (3)

tom10
tom10

Reputation: 69172

This would be more easily done using Numpy arrays throughout. Something like:

import numpy as np

N = 5
sensor1 = np.zeros((N,), dtype=float)

for i in range(N):
    sensor1[i] = BridgeValue(0) * 274.0 - 2.1
    sleep(1)

average = np.mean(sensor1)

Upvotes: 2

Brad Solomon
Brad Solomon

Reputation: 40878

You need to pass an array-like object to the a parameter of np.mean. Try:

avg_sensor1 = np.mean([sensor1_t1, sensor1_t2, sensor1_t3, sensor1_t4, sensor1_t5])

You're currently passing 5 arguments when you need to pass them as one array-like object.

In other words, the syntax for np.mean is:

numpy.mean(a, axis=None, dtype=None, out=None, ...

The way you currently are calling the function, you're passing 5 positional arguments. These get interpreted as separate parameters:

  • sensor1_t1 is passed to a
  • sensor1_t2 is passed to axis
  • sensor1_t3 is passed to dtype

...and so on.

Note that the syntax I suggested passes a list, which is one of the structures that's considered "array-like." More on that here if you are interested.

Upvotes: 3

etaloof
etaloof

Reputation: 662

Because numpy is mainly used with arrays (especially numpy.ndarray) numpy.mean expects an array as it's first argument. But you don't need to create an ndarray you can simply change np.mean(sensor1_t1, sensor1_t2, sensor1_t3, sensor1_t4, sensor1_t5) to np.mean([sensor1_t1, sensor1_t2, sensor1_t3, sensor1_t4, sensor1_t5]) and numpy will take care of the rest.

Upvotes: 0

Related Questions