sklearn doesn't have attribute 'datasets'
Question:
I have started using sckikit-learn for my work. So I was going through the tutorial which gives standard procedure to load some datasets:
$ python
>>> from sklearn import datasets
>>> iris = datasets.load_iris()
>>> digits = datasets.load_digits()
However, for my convenience, I tried loading the data in the following way:
In [1]: import sklearn
In [2]: iris = sklearn.datasets.load_iris()
However, this throws following error:
---------------------------------------------------------------------------
AttributeError Traceback (most recent call last)
<ipython-input-2-db77d2036db5> in <module>()
----> 1 iris = sklearn.datasets.load_iris()
AttributeError: 'module' object has no attribute 'datasets'
However, if I use the apparently similar method:
In [3]: from sklearn import datasets
In [4]: iris = datasets.load_iris()
It works without problem. In fact the following also works:
In [5]: iris = sklearn.datasets.load_iris()
I am completely confused about this. Am I missing something very trivial? What is the difference between the two approaches?
Answers:
sklearn
is a package. This answer said it very succinctly:
when you import a package, only variables/functions/classes in the __init__.py
file of that package are directly visible, not sub-packages or modules.
datasets
is a sub-package of sklearn
. This is why this happens:
In [1]: import sklearn
In [2]: sklearn.datasets
---------------------------------------------------------------------------
AttributeError Traceback (most recent call last)
<ipython-input-2-325a2bfc35d0> in <module>()
----> 1 sklearn.datasets
AttributeError: module 'sklearn' has no attribute 'datasets'
However, the reason why this works:
In [3]: from sklearn import datasets
In [4]: sklearn.datasets
Out[4]: <module 'sklearn.datasets' from '/home/ethan/.virtualenvs/test3/lib/python3.5/site-packages/sklearn/datasets/__init__.py'>
is that when you load the sub-package datasets
by doing from sklearn import datasets
it is automatically added to the namespace of the package sklearn
. This is one of the lesser-known “traps” of the Python import system.
Also, note that if you look at the __init__.py
for sklearn
you will see 'datasets'
as a member of __all__
, but this only allows you to do:
In [1]: from sklearn import *
In [2]: datasets
Out[2]: <module 'sklearn.datasets' from '/home/ethan/.virtualenvs/test3/lib/python3.5/site-packages/sklearn/datasets/__init__.py'>
One last point to note is that if you inspect either sklearn
or datasets
you will see that, although they are packages, their type is module
. This is because all packages are considered modules – however, not all modules are packages.
I have started using sckikit-learn for my work. So I was going through the tutorial which gives standard procedure to load some datasets:
$ python
>>> from sklearn import datasets
>>> iris = datasets.load_iris()
>>> digits = datasets.load_digits()
However, for my convenience, I tried loading the data in the following way:
In [1]: import sklearn
In [2]: iris = sklearn.datasets.load_iris()
However, this throws following error:
---------------------------------------------------------------------------
AttributeError Traceback (most recent call last)
<ipython-input-2-db77d2036db5> in <module>()
----> 1 iris = sklearn.datasets.load_iris()
AttributeError: 'module' object has no attribute 'datasets'
However, if I use the apparently similar method:
In [3]: from sklearn import datasets
In [4]: iris = datasets.load_iris()
It works without problem. In fact the following also works:
In [5]: iris = sklearn.datasets.load_iris()
I am completely confused about this. Am I missing something very trivial? What is the difference between the two approaches?
sklearn
is a package. This answer said it very succinctly:
when you import a package, only variables/functions/classes in the
__init__.py
file of that package are directly visible, not sub-packages or modules.
datasets
is a sub-package of sklearn
. This is why this happens:
In [1]: import sklearn
In [2]: sklearn.datasets
---------------------------------------------------------------------------
AttributeError Traceback (most recent call last)
<ipython-input-2-325a2bfc35d0> in <module>()
----> 1 sklearn.datasets
AttributeError: module 'sklearn' has no attribute 'datasets'
However, the reason why this works:
In [3]: from sklearn import datasets
In [4]: sklearn.datasets
Out[4]: <module 'sklearn.datasets' from '/home/ethan/.virtualenvs/test3/lib/python3.5/site-packages/sklearn/datasets/__init__.py'>
is that when you load the sub-package datasets
by doing from sklearn import datasets
it is automatically added to the namespace of the package sklearn
. This is one of the lesser-known “traps” of the Python import system.
Also, note that if you look at the __init__.py
for sklearn
you will see 'datasets'
as a member of __all__
, but this only allows you to do:
In [1]: from sklearn import *
In [2]: datasets
Out[2]: <module 'sklearn.datasets' from '/home/ethan/.virtualenvs/test3/lib/python3.5/site-packages/sklearn/datasets/__init__.py'>
One last point to note is that if you inspect either sklearn
or datasets
you will see that, although they are packages, their type is module
. This is because all packages are considered modules – however, not all modules are packages.