For loop the ticklabels, and call `set_visible()`:

    for label in cbar.ax.xaxis.get_ticklabels()[::2]:
        label.set_visible(False)

One-liner for those who are into that!

    n = 7  # Keeps every 7th label
    [l.set_visible(False) for (i,l) in enumerate(ax.xaxis.get_ticklabels()) if i % n != 0]

Just came across this thread, nice answers. 
I was looking for a way to hide every tick between the nth ticks. And found the enumerate function. So if anyone else is looking for something similar you can do it like this.


```python
for index, label in enumerate(ax.xaxis.get_ticklabels()):
    if index % n != 0:
        label.set_visible(False)
``` 


I use the following to show every 7th x label:

    plt.scatter(x, y)
    ax = plt.gca()
    temp = ax.xaxis.get_ticklabels()
    temp = list(set(temp) - set(temp[::7]))
    for label in temp:
        label.set_visible(False)
    plt.show()

It&#39;s pretty flexible, as you can do whatever you want instead of plt.scatter. Hope it helps.


I&#39;d like to change the column type from an `int` to a `uuid`. I am using the following statement

    ALTER TABLE tableA ALTER COLUMN colA SET DATA TYPE UUID;

But I get the error message

    ERROR:  column &quot;colA&quot; cannot be cast automatically to type uuid
    HINT:  Specify a USING expression to perform the conversion.

I am confused how to use `USING` to do the cast.

Postgresql change column type from int to UUID

I have the following structure to my dataFrame:

    Index: 1008 entries, Trial1.0 to Trial3.84
    Data columns (total 5 columns):
    CHUNK_NAME                    1008  non-null values
    LAMBDA                        1008  non-null values
    BETA                          1008  non-null values
    HIT_RATE                      1008  non-null values
    AVERAGE_RECIPROCAL_HITRATE    1008  non-null values
    
    chunks=[&#39;300_321&#39;,&#39;322_343&#39;,&#39;344_365&#39;,&#39;366_387&#39;,&#39;388_408&#39;,&#39;366_408&#39;,&#39;344_408&#39;,&#39;322_408&#39;,&#39;300_408&#39;]
    lam_beta=[(lambda1,beta1),(lambda1,beta2),(lambda1,beta3),...(lambda1,beta_n),(lambda2,beta1),(lambda2,beta2)...(lambda2,beta_n),........]
    
    my_df.ix[my_df.CHUNK_NAME==chunks[0]&amp;my_df.LAMBDA==lam_beta[0][0]]

I want to get the rows of the DataFrame for a particular chunk lets say `chunks[0]` and particular `lambda` value. So in this case, the output should be all rows in the DataFrame having `CHUNK_NAME=&#39;300_321&#39;` and `LAMBDA=lambda1`. There would be n rows one for each `beta` value that would be returned. But instead I get the following error. Any help in solving this problem would be appreciated.

    TypeError: cannot compare a dtyped [float64] array with a scalar of type [bool]



pandas comparison raises TypeError: cannot compare a dtyped [float64] array with a scalar of type [bool]

The labels on my horizontal colorbar are too close together and I don&#39;t want to reduce text size further:

    cbar = plt.colorbar(shrink=0.8, orientation=&#39;horizontal&#39;, extend=&#39;both&#39;, pad=0.02)
    cbar.ax.tick_params(labelsize=8)

![horizontal colorbar with bad labels][1]

I&#39;d like to preserve all ticks, but remove every other label.  

Most examples I&#39;ve found pass a user-specified list of strings to cbar.set_ticklabels().  I&#39;m looking for a general solution.  

I played around with variations of

    cbar.set_ticklabels(cbar.get_ticklabels()[::2])

and

    cbar.ax.xaxis.set_major_locator(matplotlib.ticker.MaxNLocator(nbins=4))

but I haven&#39;t found the magic combination.  

I know there must be a clean way to do this using a locator object.  


  [1]: http://i.stack.imgur.com/t52fd.png

Cleanest way to hide every nth tick label in matplotlib colorbar?

The labels on my horizontal colorbar are too close together and I don't want to reduce text size further:
<pre><code class="hljs language-ini">cbar = plt.colorbar(shrink=0.8, orientation='horizontal', extend='both', pad=0.02)
cbar.ax.tick_params(labelsize=8)
</code></pre>
<img src="http://i.stack.imgur.com/t52fd.png" alt="horizontal colorbar with bad labels">
I'd like to preserve all ticks, but remove every other label.
Most examples I've found pass a user-specified list of strings to cbar.set_ticklabels(). I'm looking for a general solution.
I played around with variations of
<pre><code class="hljs language-scss">cbar.set_ticklabels(cbar.get_ticklabels()[::2])
</code></pre>
and
<pre><code class="hljs language-ini">cbar.ax.xaxis.set_major_locator(matplotlib.ticker.MaxNLocator(nbins=4))
</code></pre>
but I haven't found the magic combination.
I know there must be a clean way to do this using a locator object.

I wrote a Python script merging two csv files, and now I want to add a header to the final csv. I tried following the suggestions reported [here][1] and I got the following error: `expected string, float found`. What is the most pythonic way to fix this?

Here is the code I am using:

    import csv

    with open(&#39;combined_file.csv&#39;, &#39;w&#39;, newline=&#39;&#39;) as outcsv:
        writer = csv.DictWriter(outcsv, fieldnames = [&quot;Date&quot;, &quot;temperature 1&quot;, &quot;Temperature 2&quot;])
        writer.writeheader()

        with open(&#39;t1.csv&#39;, &#39;r&#39;, newline=&#39;&#39;) as incsv:
            reader = csv.reader(incsv)
            writer.writerows(row + [0.0] for row in reader)

        with open(&#39;t2.csv&#39;, &#39;r&#39;, newline=&#39;&#39;) as incsv:
            reader = csv.reader(incsv)
            writer.writerows(row[:1] + [0.0] + row[1:] for row in reader)


  [1]: https://stackoverflow.com/questions/15907200/how-to-add-a-header-to-a-csv-file-in-python

Pythonically add header to a csv file

 I am new to Python to bear with me.

1. I installed Anaconda, works great.
2. I setup a Python 3 environment following the Anaconda [cmd line instructions][1], works great.
3. I [setup Anaconda&#39;s Python 3 environment as Pycharm&#39;s interpreter][2], works great.
4. I launched the [Anaconda &quot;launcher.app&quot;][3] and launched IPython Notebook. However, iPython Notebook is running Python 2 not 3.

Over three hours of Googling later, I cannot figure out how to set IPython Notebook to run Python 3 instead of 2.


  [1]: http://continuum.io/blog/anaconda-python-3
  [2]: http://docs.continuum.io/anaconda/ide_integration.html
  [3]: http://docs.continuum.io/_images/Anaconda_Launcher.png

How To Get IPython Notebook To Run Python 3?

I have two DataFrames with the following column names:

    frame_1:
    event_id, date, time, county_ID
    
    frame_2:
    countyid, state

I would like to get a DataFrame with the following columns by joining (left) on `county_ID = countyid`:

    joined_dataframe
    event_id, date, time, county, state

I cannot figure out how to do it if the columns on which I want to join are not the index.

Joining pandas DataFrames by Column names

In Pandas, when I select a label that only has one entry in the index I get back a Series, but when I select an entry that has more then one entry I get back a data frame.

Why is that?  Is there a way to ensure I always get back a data frame?


    In [1]: import pandas as pd
    
    In [2]: df = pd.DataFrame(data=range(5), index=[1, 2, 3, 3, 3])
    
    In [3]: type(df.loc[3])
    Out[3]: pandas.core.frame.DataFrame
    
    In [4]: type(df.loc[1])
    Out[4]: pandas.core.series.Series

Pandas selecting by label sometimes return Series, sometimes returns DataFrame

How do I remove a package from Pypi?

I uploaded a package to Pypi several months ago.  The package is now obsolete and I&#39;d like to formally remove it.  I cannot find any documentation on how to *remove* my package.

How to remove a package from Pypi

I&#39;m trying to colorize a Voronoi Diagram created using [`scipy.spatial.Voronoi`][1]. Here&#39;s my code:

    import numpy as np
    import matplotlib.pyplot as plt
    from scipy.spatial import Voronoi, voronoi_plot_2d

    # make up data points
    points = np.random.rand(15,2)

    # compute Voronoi tesselation
    vor = Voronoi(points)

    # plot
    voronoi_plot_2d(vor)

    # colorize
    for region in vor.regions:
        if not -1 in region:
            polygon = [vor.vertices[i] for i in region]
            plt.fill(*zip(*polygon))

    plt.show()

The resulting image:

![Voronoi Diagram][2]

As you can see some of the Voronoi regions at the border of the image are not colored. That is because some indices to the Voronoi vertices for these regions are set to `-1`, i.e., for those vertices outside the Voronoi diagram. According to the docs:

&gt; _regions:_ (list of list of ints, shape (nregions, *)) Indices of the Voronoi vertices forming each Voronoi region. **-1 indicates vertex outside the Voronoi diagram.**

In order to colorize these regions as well, I&#39;ve tried to just remove these &quot;outside&quot; vertices from the polygon, but that didn&#39;t work. I think, I need to fill in some points at the border of the image region, but I can&#39;t seem to figure out how to achieve this reasonably.

Can anyone help?

  [1]: http://docs.scipy.org/doc/scipy-dev/reference/generated/scipy.spatial.Voronoi.html
  [2]: http://i.stack.imgur.com/vmZpK.png

Colorize Voronoi Diagram

When performing `pip install -r requirements.txt`, I get the following error during the stage where it is installing `matplotlib`:


    REQUIRED DEPENDENCIES AND EXTENSIONS
                     numpy: yes [not found. pip may install it below.]
                  dateutil: yes [dateutil was not found. It is required for date
                            axis support. pip/easy_install may attempt to
                            install it after matplotlib.]
                   tornado: yes [tornado was not found. It is required for the
                            WebAgg backend. pip/easy_install may attempt to
                            install it after matplotlib.]
                 pyparsing: yes [pyparsing was not found. It is required for
                            mathtext support. pip/easy_install may attempt to
                            install it after matplotlib.]
                     pycxx: yes [Couldn&#39;t import.  Using local copy.]
                    libagg: yes [pkg-config information for &#39;libagg&#39; could not
                            be found. Using local copy.]
                  freetype: no  [pkg-config information for &#39;freetype2&#39; could
                            not be found.]

   ...


    The following required packages can not be built:

                        * freetype

Shouldn&#39;t `pip install -r requirements.txt` also install freetype? How should freetype be installed in Ubuntu 12.04 so it works with `matplotlib`?

Ubuntu running `pip install` gives error &#39;The following required packages can not be built: * freetype&#39;

I have a problem making histograms from pandas series objects and I can&#39;t understand why it does not work. The code has worked fine before but now it does not.

Here is a bit of my code (specifically, a pandas series object I&#39;m trying to make a histogram of):

    type(dfj2_MARKET1[&#39;VSPD2_perc&#39;])

which outputs the result: 
    `pandas.core.series.Series`

Here&#39;s my plotting code:

    fig, axes = plt.subplots(1, 7, figsize=(30,4))
    axes[0].hist(dfj2_MARKET1[&#39;VSPD1_perc&#39;],alpha=0.9, color=&#39;blue&#39;)
    axes[0].grid(True)
    axes[0].set_title(MARKET1 + &#39;  5-40 km / h&#39;)

Error message:

        AttributeError                            Traceback (most recent call last)
        &lt;ipython-input-75-3810c361db30&gt; in &lt;module&gt;()
          1 fig, axes = plt.subplots(1, 7, figsize=(30,4))
          2 
        ----&gt; 3 axes[1].hist(dfj2_MARKET1[&#39;VSPD2_perc&#39;],alpha=0.9, color=&#39;blue&#39;)
          4 axes[1].grid(True)
          5 axes[1].set_xlabel(&#39;Time spent [%]&#39;)
    
        C:\Python27\lib\site-packages\matplotlib\axes.pyc in hist(self, x, bins, range, normed,          weights, cumulative, bottom, histtype, align, orientation, rwidth, log, color, label,    stacked, **kwargs)
       8322             # this will automatically overwrite bins,
       8323             # so that each histogram uses the same bins
    -&gt; 8324             m, bins = np.histogram(x[i], bins, weights=w[i], **hist_kwargs)
       8325             m = m.astype(float) # causes problems later if it&#39;s an int
       8326             if mlast is None:
    
        C:\Python27\lib\site-packages\numpy\lib\function_base.pyc in histogram(a, bins, range,     normed, weights, density)
        158         if (mn &gt; mx):
        159             raise AttributeError(
    --&gt; 160                 &#39;max must be larger than min in range parameter.&#39;)
        161 
        162     if not iterable(bins):
    
    AttributeError: max must be larger than min in range parameter.



Matplotlib/Pandas error using histogram

I want to hide my ticks label on a plot I created, but keep this tick itself (the little marks on the axis). When I try to use what I&#39;ve found [here](https://stackoverflow.com/questions/2176424/hiding-axis-text-in-matplotlib-plots), for example, the entire tick is removed, and not just the labels. How can I remove only the labels then? 


How to hide ticks label in python but keep the ticks in place?

I keep seeing people use `%pylab` in various code snippits, particularly with iPython. However, I cannot see where `%pylab` is mentioned anywhere in Learning Python (and the few other Python books I have) and am not really sure what it means.

I&#39;m sure the answer is simple, but can anyone enlighten me?

Content Type	Original Author	Original Content on Stackoverflow
Question	David Shean	View Question on Stackoverflow
Solution 1 - Python	HYRY	View Answer on Stackoverflow
Solution 2 - Python	malla	View Answer on Stackoverflow
Solution 3 - Python	Jacob Scherffenberg-Møller	View Answer on Stackoverflow
Solution 4 - Python	Ben	View Answer on Stackoverflow

Cleanest way to hide every nth tick label in matplotlib colorbar?

Python Problem Overview

Python Solutions

Solution 1 - Python

Solution 2 - Python

Solution 3 - Python

Solution 4 - Python

pandas comparison raises TypeError: cannot compare a dtyped [float64] array with a scalar of type [bool]

Postgresql change column type from int to UUID

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