Converting tuple into array and calling the new array

Question

I am developing custom regression analysis routine and ran into a problem trying to call tuple element for calculations:

EV = np.linalg.eig(xMe)
print EV

The result of print EV is below:

(array([  4.59554481e-02,   1.73592040e+04]), matrix([[-0.99977087, -0.02140571],
    [ 0.02140571, -0.99977087]]))

It is a tuple. I need to access each element in the first array in tuple ( 4.59554481e-02, 1.73592040e+04). When I try to convert tuple using:

lEV = np.asarray(EV)

I get the following error:

ValueError                                Traceback (most recent call last)
<ipython-input-172-f46907801d9e> in <module>()
 42 print EV
 43 
---> 44 lEV = np.asarray(EV)

462     return array(a, dtype, copy=False, order=order)
463 
464 def asanyarray(a, dtype=None, order=None):

ValueError: could not broadcast input array from shape (2,2) into shape (2)

I am new to Python and probably there is a very easy way to access these two elements but I can not figure it out.

Silly of me:) It is easy: m= EV[0] and then call m[0] and m[1]. Any optimization suggestions are greatly appreciated — Toly
– Toly, Commented Sep 18, 2015 at 3:32

m00am · Accepted Answer · 2015-09-18 09:25:31Z

1

A pythonic way to do this would be to use tuple unpacking:

>>> import numpy as np

>>> a = np.array([[0,17],[42,23]])
>>> eigenvalues, eigenvectors = np.linalg.eig(a)
>>> print eigenvalues
array([-17.59037642,  40.59037642])

>>> print eigenvectors
array([[-0.69493692, -0.38630591],
       [ 0.71907071, -0.92237072]])

This allows you to unpack the two items of the tuple into two variables. On those variables you can now use a standard for loop:

>>> for value in eigenvalues:
...    print(value)
-17.5903764156
40.5903764156

Alternatively (if you know how many values you will get) you can use tuple unpacking again:

>>> ev_1, ev_2 = eigenvalues
>>> print ev_1
-17.5903764156

>>> print ev_2
40.5903764156

answered Sep 18, 2015 at 9:25

m00am

6,31612 gold badges60 silver badges74 bronze badges

Sign up to request clarification or add additional context in comments.

Collectives™ on Stack Overflow

Converting tuple into array and calling the new array

1 Answer 1

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

Comments

Your Answer

Sign up or log in

Post as a guest

Related