To expand on what Ignacio said:

`a == b` and `a != b` test whether two objects have the same *value*. You can override an object&#39;s `__eq__` and `__ne__` methods to determine what that means.

`a is b` and `a is not b` test whether two objects are the same thing. It&#39;s like doing `id(a) == id(b)`

It&#39;s not relational comparison, it&#39;s identity. And it translates to `not (A is B)`.

[python 2.7.3 documentation, 5.9. Comparisons][1]:

&gt; The operators &lt;, &gt;, ==, &gt;=, &lt;=, and != compare the values of two objects. 

and about operator **is** in the same chapter:

&gt;The operators is and is not test for object identity: x is y is true if and only if x and y are the same object. x is not y yields the inverse truth value.

 [1]: http://docs.python.org/reference/expressions.html

    A != B

means that &quot;A *is not equal to* B&quot;, not &quot;A *is equal to not* B&quot;.

This is currently what I have to delete the file but it&#39;s not working. I thought it may be permission problems or something but it wasn&#39;t. The file that I am testing with is empty and exists, so not sure why it doesn&#39;t delete it.

    UserInput.prompt(&quot;Enter name of file to delete&quot;);
    String name = UserInput.readString();
    File file = new File(&quot;\\Files\\&quot; + name + &quot;.txt&quot;);
    file.delete();

Any help would be GREATLY appreciated!

I now have:

     

    File file = new File(catName + &quot;.txt&quot;);
    String path = file.getCanonicalPath();
    File filePath = new File(path);
    filePath.delete();

To try and find the correct path at run time so that if the program is transferred to a different computer it will still find the file.

Java &#39;file.delete()&#39; Is not Deleting Specified File

For data that is known to have seasonal, or daily patterns I&#39;d like to use fourier analysis be used to make predictions. After running fft on time series data, I obtain coefficients. How can I use these coefficients for prediction? 

I believe FFT assumes all data it receives constitute one period, then, if I simply regenerate data using ifft, I am also regenerating the continuation of my function, so can I use these values for future values? 

Simply put: I run fft for t=0,1,2,..10 then using ifft on coef, can I use regenerated time series for t=11,12,..20 ?  

Using fourier analysis for time series prediction

I notice there is a comparison operator `is not`. Should I literally translate it into 

    != 

instead of 

    == not


python &#39;is not&#39; operator

I notice there is a comparison operator <code>is not</code>. Should I literally translate it into
<pre><code class="hljs language-diff">!= 
</code></pre>
instead of
<pre><code class="hljs">== not
</code></pre>

Let&#39;s say I have a file. How do I write &quot;hello&quot; TAB &quot;alex&quot;?


How do I write a &quot;tab&quot; in Python?

I was trying to install Python packages a system I recently gained access to. I was trying to take advantage of Python&#39;s relatively new [per user site-packages directory][1], and the new option `--user`. (The option is [currently undocumented][2], however it exists for Python 2.6+; you can see the help by running `python setup.py install --help`.)

When I tried running

    python setup.py install --user

on any package I downloaded, I always got the following error:

    error: can&#39;t combine user with with prefix/exec_prefix/home or install_(plat)base

The error was extremely perplexing because, as you can see, I wasn&#39;t providing the `--prefix`, `--exec-prefix`, `--install-base`, or `--install-platbase` flags as command line options. I wasted a lot of time trying to figure out what the problem was. I document my answer below, in hopes to spare some other poor soul a few hours of [yak shaving][3].


  [1]: http://docs.python.org/whatsnew/2.6.html#pep-370-per-user-site-packages-directory
  [2]: http://bugs.python.org/issue10745
  [3]: http://en.wiktionary.org/wiki/yak_shaving

Combine --user with --prefix error with setup.py install

I have a Python program that spawns many threads, runs 4 at a time, and each performs an expensive operation. Pseudocode:

    for object in list:
        t = Thread(target=process, args=(object))
        # if fewer than 4 threads are currently running, t.start(). Otherwise, add t to queue

But when the program is run, Activity Monitor in OS X shows that 1 of the 4 logical cores is at 100% and the others are at nearly 0. Obviously I can&#39;t force the OS to do anything but I&#39;ve never had to pay attention to performance in multi-threaded code like this before so I was wondering if I&#39;m just missing or misunderstanding something.

Thanks.


Python threads all executing on a single core

I have this code:

    &gt;&gt;&gt; for i in xrange(20):
    ...     print &#39;a&#39;,
    ... 
    a a a a a a a a a a a a a a a a a a a a

I want to output `&#39;a&#39;`, without `&#39; &#39;` like this:

    aaaaaaaaaaaaaaaaaaaa

Is it possible?

Printing without newline (print &#39;a&#39;,) prints a space, how to remove?

In [my previous question I got an excellent answer](https://stackoverflow.com/questions/4087919/how-can-i-improve-my-paw-detection/4092160#4092160) that helped me detect where a paw hit a pressure plate, but now I&#39;m struggling to link these results to their corresponding paws:

![alt text][1]

I manually annotated the paws (RF=right front, RH= right hind, LF=left front, LH=left hind).

As you can see there&#39;s clearly a repeating pattern and it comes back in almost every measurement. [Here&#39;s a link to a presentation of 6 trials that were manually annotated.](https://docs.google.com/viewer?a=v&amp;pid=explorer&amp;chrome=true&amp;srcid=0B1W3cjBV_DpNYjNhYjFjYzctZjJjNi00ODVkLWExMjctYmQ5YWJhOWU3ZDg0&amp;hl=en&amp;authkey=CO6_lbIE)

My initial thought was to use heuristics to do the sorting, like:

- There&#39;s a ~60-40% ratio in weight bearing between the front and hind paws;
- The hind paws are generally smaller in surface;
- The paws are (often) spatially divided in left and right.

However, I’m a bit skeptical about my heuristics, as they would fail on me as soon as I encounter a variation I hadn’t thought off. They also won’t be able to cope with measurements from lame dogs, whom probably have rules of their own. 

Furthermore, the annotation suggested by Joe sometimes get&#39;s messed up and doesn&#39;t take into account what the paw actually looks like.

Based on the answers I received [on my question about peak detection within the paw](https://stackoverflow.com/questions/3684484), I’m hoping there are more advanced solutions to sort the paws. Especially because the pressure distribution and the progression thereof are different for each separate paw, almost like a fingerprint. I hope there&#39;s a method that can use this to cluster my paws, rather than just sorting them in order of occurrence. 

![alt text][2]

**So I&#39;m looking for a better way to sort the results with their corresponding paw.** 

For anyone up to the challenge, [I have pickled a dictionary](https://stackoverflow.com/questions/3685265/how-to-write-a-multidimensional-array-to-a-text-file/3685295#3685295) with [all the sliced arrays that contain the pressure data of each paw](http://dl.dropbox.com/u/5207386/walk_sliced_data) (bundled by measurement) and [the slice that describes their location](http://dl.dropbox.com/u/5207386/walk_data_slices) (location on the plate and in time). 

To clarfiy: walk_sliced_data is a dictionary that contains [&#39;ser_3&#39;, &#39;ser_2&#39;, &#39;sel_1&#39;, &#39;sel_2&#39;, &#39;ser_1&#39;, &#39;sel_3&#39;], which are the names of the measurements. Each measurement contains another dictionary, [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10] (example from &#39;sel_1&#39;) which represent the impacts that were extracted. 

Also note that &#39;false&#39; impacts, such as where the paw is partially measured (in space or time) can be ignored. They are only useful because they can help recognizing a pattern, but 
won&#39;t be analyzed. 

And for anyone interested, [I’m keeping a blog with all the updates regarding the project!](http://www.flipserd.com/blog)

  [1]: http://i.stack.imgur.com/1KbIz.png
  [2]: http://i.stack.imgur.com/hFmOn.png

Content Type	Original Author	Original Content on Stackoverflow
Question	nos	View Question on Stackoverflow
Solution 1 - Python	Thomas K	View Answer on Stackoverflow
Solution 2 - Python	Ignacio Vazquez-Abrams	View Answer on Stackoverflow
Solution 3 - Python	2r2w	View Answer on Stackoverflow
Solution 4 - Python	zsalzbank	View Answer on Stackoverflow

python 'is not' operator

Python Problem Overview

Python Solutions

Solution 1 - Python

Solution 2 - Python

Solution 3 - Python

Solution 4 - Python

Using fourier analysis for time series prediction

Java 'file.delete()' Is not Deleting Specified File

Attributions