howto make Python list from numpy.array?

[dmitrey]

howto make Python list from numpy.array?
Thx, D.

 

[John Nagle]

howto make Python list from numpy.array?
Thx, D.

lst = map(None, arr) // for 1D arrays.

John Nagle

 

[Terry Reedy]

| howto make Python list from numpy.array?

I Googled 'numpy array Python list' and looked at the third hit
(PythonBasics) and at the bottom found your answer. About 30 seconds or
less.

tjr

 

[Amaury Forgeot d'Arc]

Hello,

John Nagle a écrit :

lst = map(None, arr) // for 1D arrays.

Which can be expressed more simply as:
lst = list(arr)

 

[dmitrey]

Thanks all.
I tried all the approaches but they don't work in my situation
I have a variable x that can be
x = 1
x = [1, 2, 3]
x = numpy.array([1,2,3])
so all troubles are with 1st caseTraceback (most recent call last):
Traceback (most recent call last):
Traceback (most recent call last):

Here I used Python 2.4.3, numpy 1.02

 

[Robert Kern]

Hello,

John Nagle a écrit :

Which can be expressed more simply as:
lst = list(arr)

For N-D arrays, that will give you a list of arrays. If you want a list of lists
(of lists of lists ... etc N times), use the .tolist() method of arrays.

--
Robert Kern

"I have come to believe that the whole world is an enigma, a harmless enigma
that is made terrible by our own mad attempt to interpret it as though it had
an underlying truth."
-- Umberto Eco

 

[Robert Kern]

Thanks all.
I tried all the approaches but they don't work in my situation
I have a variable x that can be
x = 1
x = [1, 2, 3]
x = numpy.array([1,2,3])
so all troubles are with 1st caseTraceback (most recent call last):
Traceback (most recent call last):
Traceback (most recent call last):
File "<string>", line 1, in <string>
ValueError: rank-0 arrays don't convert to lists.

Here I used Python 2.4.3, numpy 1.02

All of these results are entirely correct. A scalar (or rank-0 array) is not a
sequence.

If you have a need to transform a scalar into a sequence (e.g. transform 1 to
[1]), then you can use numpy.atleast_1d(x).tolist().

--
Robert Kern

"I have come to believe that the whole world is an enigma, a harmless enigma
that is made terrible by our own mad attempt to interpret it as though it had
an underlying truth."
-- Umberto Eco

 

[Steven D'Aprano]

Thanks all.
I tried all the approaches but they don't work in my situation
I have a variable x that can be
x = 1
x = [1, 2, 3]
x = numpy.array([1,2,3])
so all troubles are with 1st case

And yet your question was about the third case:

"howto make Python list from numpy.array?"


You should have asked:

How do I make a Python list from an int?

And the answer would be:

x = 1
lst = [x]

Another answer would be:

x = 1
lst = ["existing", "list"]
lst.append(x)