It&#39;s in the [python docs][1].

    import datetime
    datetime.datetime.combine(datetime.date(2011, 1, 1), 
                              datetime.time(10, 23))

returns

    datetime.datetime(2011, 1, 1, 10, 23)


   [1]: http://docs.python.org/release/2.6/library/datetime.html#datetime.datetime.combine

Let&#39;s say that I have a date in R and it&#39;s formatted as follows.

       date      
    2012-02-01 
    2012-02-01
    2012-02-02

Is there any way in R to add another column with the day of the week associated with the date? The dataset is really large, so it would not make sense to go through manually and make the changes.

    df = data.frame(date=c(&quot;2012-02-01&quot;, &quot;2012-02-01&quot;, &quot;2012-02-02&quot;)) 

So after adding the days, it would end up looking like:

       date       day
    2012-02-01   Wednesday
    2012-02-01   Wednesday
    2012-02-02   Thursday

Is this possible? Can anyone point me to a package that will allow me to do this?
Just trying to automatically generate the day by the date.


Find the day of a week

I am using Python 3.2 on Windows 7.  When I open the Python shell, how can I know what the current directory is and how can I change it to another directory where my modules are?

How to know/change current directory in Python shell?

I have two objects that represent the same event instance --- one holds the date, the other the time of this event, and I want to create a datetime object. 

Since one can&#39;t simply add date and time objects (following call fails): 

     datetime.date(2011, 01, 01) + datetime.time(10, 23)



Pythonic way to combine datetime.date and datetime.time objects

I have two objects that represent the same event instance --- one holds the date, the other the time of this event, and I want to create a datetime object.
Since one can't simply add date and time objects (following call fails):
<pre><code class="hljs language-lua"> datetime.date(2011, 01, 01) + datetime.time(10, 23)
</code></pre>

I have a time to which I want to add an hour:

    $time = &#39;10:09&#39;;

I&#39;ve tried:

    $time = strtotime(&#39;+1 hour&#39;);

    strtotime(&#39;+1 hour&#39;, $time);

    $time = date(&#39;H:i&#39;, strtotime(&#39;+1 hour&#39;));

But none of the above work.

Adding 1 hour to time variable

I&#39;m trying to generate an [RFC 3339][1] UTC timestamp in Python. So far I&#39;ve been able to do the following:

    &gt;&gt;&gt; d = datetime.datetime.now()
    &gt;&gt;&gt; print d.isoformat(&#39;T&#39;)
    2011-12-18T20:46:00.392227

My problem is with setting the UTC offset.

According to the [docs][2], the classmethod `datetime.now([tz])`, takes an optional `tz` argument where `tz must be an instance of a class tzinfo subclass`, and `datetime.tzinfo` is `an abstract base class for time zone information objects.`

This is where I get lost- How come tzinfo is an abstract class, and how am I supposed to implement it? 

---

(**NOTE:** In PHP it&#39;s as simple as `timestamp = date(DATE_RFC3339);`, which is why I can&#39;t understand why Python&#39;s approach is so convoluted...)

  [1]: https://www.rfc-editor.org/rfc/rfc3339
  [2]: http://docs.python.org/library/datetime.html

Generate RFC 3339 timestamp in Python

How can I get UTC/GMT +/- time stamp using PHP&#39;s date() function? For example, if I try

    date(&quot;Y-m-d H:i:s&quot;, time()); 

I will get Unix time stamp; but I need to get UTC/GMT time stamp with string GMT/UTC+/-0400 or GMT/UTC+/-1000 based on local timings.

get UTC time in PHP

I am dealing with dates in Python and I need to convert them to UTC timestamps to be used
inside Javascript. The following code does not work:

    &gt;&gt;&gt; d = datetime.date(2011,01,01)
    &gt;&gt;&gt; datetime.datetime.utcfromtimestamp(time.mktime(d.timetuple()))
    datetime.datetime(2010, 12, 31, 23, 0)

Converting the date object first to datetime also does not help. I tried the example at this [link][1] from, but:

    from pytz import utc, timezone
    from datetime import datetime
    from time import mktime
    input_date = datetime(year=2011, month=1, day=15)

and now either:

    mktime(utc.localize(input_date).utctimetuple())

or

    mktime(timezone(&#39;US/Eastern&#39;).localize(input_date).utctimetuple())

does work.

So general question: how can I get a date converted to seconds since epoch according to UTC?


  [1]: http://www.reddit.com/r/Python/comments/hkw9u/create_utc_timestamp_for_given_date

Converting datetime.date to UTC timestamp in Python

How can I calculate the date of the next Friday?

How to calculate next Friday?

I&#39;m trying to write a Python script that starts a subprocess, and writes to the subprocess stdin. I&#39;d also like to be able to determine an action to be taken if the subprocess crashes.

The process I&#39;m trying to start is a program called `nuke` which has its own built-in version of Python which I&#39;d like to be able to submit commands to, and then tell it to quit after the commands execute. So far I&#39;ve worked out that if I start Python on the command prompt like and then start `nuke` as a subprocess then I can type in commands to `nuke`, but I&#39;d like to be able to put this all in a script so that the master Python program can start `nuke` and then write to its [standard input][1] (and thus into its built-in version of Python) and tell it to do snazzy things, so I wrote a script that starts `nuke` like this:

    subprocess.call([&quot;C:/Program Files/Nuke6.3v5/Nuke6.3&quot;, &quot;-t&quot;, &quot;E:/NukeTest/test.nk&quot;])

Then nothing happens because `nuke` is waiting for user input. How would I now write to standard input?

I&#39;m doing this because I&#39;m running a plugin with `nuke` that causes it to crash intermittently when rendering multiple frames. So I&#39;d like this script to be able to start `nuke`, tell it to do something and then if it crashes, try again. So if there is a way to catch a crash and still be OK then that&#39;d be great.

  [1]: https://en.wikipedia.org/wiki/Standard_streams#Standard_input_.28stdin.29


How do I write to a Python subprocess&#39; stdin?

How can I put text in the top left (or top right) corner of a matplotlib figure, e.g. where a top left legend would be, or on top of the plot but in the top left corner?  E.g. if it&#39;s a plt.scatter(), then something that would be within the square of the scatter, put in the top left most corner.

I&#39;d like to do this without ideally knowing the scale of the scatterplot being plotted for example, since it will change from dataset to data set.  I just want it the text to be roughly in the upper left, or roughly in the upper right. With legend type positioning it should not overlap with any scatter plot points anyway.

thanks!

Putting text in top left corner of matplotlib plot

Let’s say I have a NumPy array, `a`:

&lt;!--language: python--&gt;

    a = np.array([
        [1, 2, 3],
        [2, 3, 4]
        ])

And I would like to add a column of zeros to get an array, `b`:

&lt;!--language: python--&gt;

    b = np.array([
        [1, 2, 3, 0],
        [2, 3, 4, 0]
        ])

How can I do this easily in NumPy?


How to add an extra column to a NumPy array

I&#39;m looking for a way to use something like the modulus operator in django. What I am trying to do is to add a classname to every fourth element in a loop.

With modulus it would look like this:

    {% for p in posts %}
        &lt;div class=&quot;post width1 height2 column {% if forloop.counter0 % 4 == 0 %}first{% endif %}}&quot;&gt;
            &lt;div class=&quot;preview&quot;&gt;
                
            &lt;/div&gt;
            &lt;div class=&quot;overlay&quot;&gt;
                
            &lt;/div&gt;
            &lt;h2&gt;p.title&lt;/h2&gt;
        &lt;/div&gt;
    {% endfor %}

Of course this doesn&#39;t work because % is a reserved character. Is there any other way to do this?


Modulus % in Django template

To state it in a general form, I&#39;m looking for a way to join several points with a **gradient color line** using **matplotlib**, and I&#39;m not finding it anywhere.
To be more specific, I&#39;m plotting a 2D random walk with a one color line. But, as the points have a relevant sequence, I would like to look at the plot and see where the data has moved. A gradient colored line would do the trick. Or a line with gradually changing transparency.

I&#39;m just trying to improve the vizualization of my data. Check out this beautiful image produced by the ggplot2 package of R. I&#39;m looking for the same in matplotlib. Thanks.

![enter image description here][1]


  [1]: http://i.stack.imgur.com/7sNmT.png

Content Type	Original Author	Original Content on Stackoverflow
Question	jb.	View Question on Stackoverflow
Solution 1 - Datetime	eumiro	View Answer on Stackoverflow

Pythonic way to combine datetime.date and datetime.time objects

Datetime Problem Overview

Datetime Solutions

Solution 1 - Datetime

How to know/change current directory in Python shell?

Find the day of a week

Attributions