Python Numpy: Sub-arrays to one list

Question

I have a numpy array x that looks like this:

In: x
Out: 
array([[array([ 1.]), 0.0],
       [array([-0.00770808]), array([ 0.90825723])],
       [array([-0.0358526]), array([ 0.59267366])],
       [array([ 0.0088844]), array([ 0.89480382])],
       [array([ 0.0387529]), array([ 0.56483939])],
       [array([-0.08508252]), array([ 0.20664826])],
       [array([-0.04159874]), array([ 0.538443])],
       [array([ 0.07626737]), array([ 0.25998565])],
       [array([ 0.00222671]), array([ 0.97386301])],
       [array([-0.12652962]), array([ 0.0621885])],
       [array([ 0.01404373]), array([ 0.83703121])]], dtype=object)

You see that there are 11 tuples. I want to create a list with each of the first elements from each tuples. That would be a list that looks like this: [1, -0.00770808, -0.0358526, 0.0088844, 0.0387529 ... ]. How can I do this?

Ashwini Chaudhary · Accepted Answer · 2014-06-25 21:45:36Z

3

You can do something like this:

>>> x[:,0].astype('float')
array([ 1.        , -0.00770808, -0.0358526 ,  0.0088844 ,  0.0387529 ,
       -0.08508252, -0.04159874,  0.07626737,  0.00222671, -0.12652962,
        0.01404373])

answered Jun 25, 2014 at 21:45

Ashwini Chaudhary

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2 Comments

Plug4 Over a year ago

Ohhh I see ... astype('float')...that's what I was missing... I just need the list as well so list(x[:,0].astype('float')) Thanks!

Ashwini Chaudhary Over a year ago

@Plug4 You can use x[:,0].astype('float').tolist() if you need a list.

timgeb · Accepted Answer · 2014-06-25 21:48:13Z

1

You can simply issue

mylist = [a[0][0] for a in x]

where x is your array. Demo:

>>> mylist = [a[0][0] for a in x]
>>> mylist
[1.0, -0.00770808, -0.035852599999999998, 0.0088844000000000006, 0.0387529, -0.085082519999999995, -0.041598740000000002, 0.076267370000000001, 0.0022267099999999998, -0.12652962000000001, 0.014043730000000001]

answered Jun 25, 2014 at 21:48

timgeb

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