The behavior you are seeing can be caused if there is a module (`foo.py`) or package (`foo/__init__.py`) in your current directory that has a conflicting name.

In your case, I suspect there is a file named `prediction.py`, and you&#39;re getting that instead of the `prediction` package in your `examples` directory.


I have about 200 grayscale PNG images stored within a directory like this.

    1.png
    2.png
    3.png
    ...
    ...
    200.png

I want to import all the PNG images as NumPy arrays.
How can I do this?

Importing PNG files into Numpy?

The member [begin][1] has two overloadings one of them is `const_iterator begin() const;`. There&#39;s also the [cbegin][2] `const_iterator cbegin() const noexcept;`. Both of them returns `const_iterator` to the begin of a list. What&#39;s the difference?


  [1]: http://www.cplusplus.com/reference/vector/vector/begin/
  [2]: http://www.cplusplus.com/reference/vector/vector/cbegin/

What is the difference between cbegin and begin for vector?

I have a project having the structure

    /example
    ../prediction
    ....__init__.py
    ....a.py

PYTHONPATH is pointed to /example

now I open the python in terminal and type

    import prediction

it succeeded, but if I type

    import prediction.a

it returns error

    ImportError: No module named &#39;prediction.a&#39;; &#39;prediction&#39; is not a package

why is that? isn&#39;t that already imported as a package

Import error, No module named xxxx

I have a project having the structure
<pre><code class="hljs language-bash">/example
../prediction
....__init__.py
....a.py
</code></pre>
PYTHONPATH is pointed to /example
now I open the python in terminal and type
<pre><code class="hljs language-arduino">import prediction
</code></pre>
it succeeded, but if I type
<pre><code class="hljs language-arduino">import prediction.a
</code></pre>
it returns error
<pre><code class="hljs language-java">ImportError: No module named 'prediction.a'; 'prediction' is not a package
</code></pre>
why is that? isn't that already imported as a package

How can I get the total number of hours in a Pandas timedelta?

For example:

    &gt;&gt;&gt; td = pd.Timedelta(&#39;1 days 2 hours&#39;)
    &gt;&gt;&gt; td.get_total_hours()
    26

Note: as per the documentation, the `.hours` attribute will return the hours *component*:

    &gt;&gt;&gt; td.hours
    2

Get total number of hours from a Pandas Timedelta?

Python pandas has a pct_change function which I use to calculate the returns for stock prices in a dataframe:

    ndf[&#39;Return&#39;]= ndf[&#39;TypicalPrice&#39;].pct_change()
I am using the following code to get logarithmic returns, but it gives the exact same values as the pct.change() function:

    ndf[&#39;retlog&#39;]=np.log(ndf[&#39;TypicalPrice&#39;].astype(&#39;float64&#39;)/ndf[&#39;TypicalPrice&#39;].astype(&#39;float64&#39;).shift(1))
    #np is for numpy

Logarithmic returns in pandas dataframe

I was recently having a problem with a python ImportError, where the module was found when running on my local computer but not found on the CI server. I solved this problem by swapping `sys.path.append(path)` in my script with `sys.path.insert(0, path)` where `path` is the string module location.

Since this is my module and not an installed package ([related question][1]), why does the order of paths fix this problem?


  [1]: https://stackoverflow.com/questions/10095037/why-use-sys-path-appendpath-instead-of-sys-path-insert1-path

Effect of using sys.path.insert(0, path) and sys.path(append) when loading modules

Suppose there are two packages in a project: `some_package` and `another_package`.

    # some_package/foo.py:
    def bar():
        print(&#39;hello&#39;)

&lt;!-- --&gt;

    # another_package/function.py
    from some_package.foo import bar

    def call_bar():
        # ... code ...
        bar()
        # ... code ...

I want to test `another_package.function.call_bar` mocking out `some_package.foo.bar` because it has some network I/O I want to avoid. 

Here is a test:

    # tests/test_bar.py
    from another_package.function import call_bar

    def test_bar(monkeypatch):
        monkeypatch.setattr(&#39;some_package.foo.bar&#39;, lambda: print(&#39;patched&#39;))
        call_bar()
        assert True

To my surprise it outputs `hello` instead of `patched`. I tried to debug this thing, putting an IPDB breakpoint in the test. When I manually import `some_package.foo.bar` after the breakpoint and call `bar()` I get `patched`.

On my real project the situation is even more interesting. If I invoke pytest in the project root my function isn&#39;t patched, but when I specify `tests/test_bar.py` as an argument - it works.

As far as I understand it has something to do with the `from some_package.foo import bar` statement. If it&#39;s being executed before monkeypatching is happening then patching fails. But on the condensed test setup from the example above patching does not work in both cases.

And why does it work in IPDB REPL after hitting a breakpoint?

Pytest monkeypatch isn&#39;t working on imported function

How to get document vectors of two text documents using Doc2vec?
I am new to this, so it would be helpful if someone could point me in the right direction / help me with some tutorial

I am using gensim.

    doc1=[&quot;This is a sentence&quot;,&quot;This is another sentence&quot;]
    documents1=[doc.strip().split(&quot; &quot;) for doc in doc1 ]
    model = doc2vec.Doc2Vec(documents1, size = 100, window = 300, min_count = 10, workers=4)

I get 

&gt; AttributeError: &#39;list&#39; object has no attribute &#39;words&#39;

whenever I run this.




Doc2vec: How to get document vectors

I know of these two questions about `__init__.py` and `__main__.py`:

https://stackoverflow.com/questions/448271

https://stackoverflow.com/questions/4042905

But I don&#39;t really understand the difference between them. Or I could say I don&#39;t understand how they interact together.

What is the difference between __init__.py and __main__.py?

There is a `-&gt;`, or dash-greater-than symbol at the end of a python method, and I&#39;m not sure what it means. One might call it an arrow as well.

Here is the example:


    @property
    def get_foo(self) -&gt; Foo:
        return self._foo

where `self._foo` is an instance of Foo. 

My guess is that it is some kind of static type declaration, to tell the interpreter that `self._foo` is of type Foo. But when I tested this, if `self._foo` is not an instance of Foo, nothing unusual happens. Also, if `self._foo` is of a type other than Foo, let&#39;s say it was an `int`, then `type(SomeClass.get_foo())` returns `int`. So, what&#39;s the point of `-&gt; Foo`?

This concept is hard to lookup because it is a symbol without a common name, and the term &quot;arrow&quot; is misleading.


What does the -&gt; (dash-greater-than arrow symbol) mean in a Python method signature?

Why does Python 3 allow &quot;00&quot; as a literal for 0 but not allow &quot;01&quot; as a literal for 1? Is there a good reason? This inconsistency baffles me. (And we&#39;re talking about Python 3, which purposely broke backward compatibility in order to achieve goals like consistency.)

For example:

    &gt;&gt;&gt; from datetime import time
    &gt;&gt;&gt; time(16, 00)
    datetime.time(16, 0)
    &gt;&gt;&gt; time(16, 01)
      File &quot;&lt;stdin&gt;&quot;, line 1
        time(16, 01)
                  ^
    SyntaxError: invalid token
    &gt;&gt;&gt;

Why does Python 3 allow &quot;00&quot; as a literal for 0 but not allow &quot;01&quot; as a literal for 1?

Based on this [comment][1] and the referenced documentation, Pickle 4.0+ from Python 3.4+ should be able to pickle byte objects larger than 4&#160;GB. 

However, using python 3.4.3 or python 3.5.0b2 on Mac OS X 10.10.4, I get an error when I try to pickle a large byte array:

    &gt;&gt;&gt; import pickle
    &gt;&gt;&gt; x = bytearray(8 * 1000 * 1000 * 1000)
    &gt;&gt;&gt; fp = open(&quot;x.dat&quot;, &quot;wb&quot;)
    &gt;&gt;&gt; pickle.dump(x, fp, protocol = 4)
    Traceback (most recent call last):
      File &quot;&lt;stdin&gt;&quot;, line 1, in &lt;module&gt;
    OSError: [Errno 22] Invalid argument

Is there a bug in my code or am I misunderstanding the documentation?

  [1]: https://stackoverflow.com/a/29704623/1202808

Content Type	Original Author	Original Content on Stackoverflow
Question	Hello lad	View Question on Stackoverflow
Solution 1 - Python	larsks	View Answer on Stackoverflow

Import error, No module named xxxx

Python Problem Overview

Python Solutions

Solution 1 - Python

What is the difference between cbegin and begin for vector?

Importing PNG files into Numpy?

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