from the desk of stinkpot

hide tick lines in matplotlib

Lawrence David — Thu, 02 Feb 2012 03:41:49 +0000

to hide the tick lines in matplotlib:

xaxis = ax.xaxis

xaxis.set_ticks_position(‘none’)

horizontal grid lines in matplotlib

Lawrence David — Thu, 02 Feb 2012 01:20:23 +0000

to create only horizontal grid lines in matplotlib:

fig, ax = pylab.subplots(1)

ax.xaxis.grid(True)

pylab.grid()

label x-axis with strings, instead of numbers, in matplotlib

Lawrence David — Tue, 31 Jan 2012 16:14:57 +0000

let’s say you’ve made a bar plot and you want to label the bars by strings (e.g. ‘A’, ‘B’) instead of the default number range. to do with a list of labels named ‘bar_l’:

import pylab as pl

pl.xticks(np.arange(len(bar_l)),bar_l,rotation=45)

change default line color order in matplotlib

Lawrence David — Thu, 29 Sep 2011 03:07:27 +0000

to change the default line color order (color cycle in matplotlib-speak):

ax.set_color_cycle(['green', 'orange', 'blue', 'red','brown','pink'])

note that this will also go ahead and reset the line counter.

draw fill_between matplotlib plot with nans

Lawrence David — Tue, 20 Sep 2011 20:05:59 +0000

nan’s cause problems with the fill_between plots in matplotlib.

to fix, use the “where” input argument:

fig, ax = pl.subplots(1)

ax.fill_between(x_v,0,y_v,where=np.isfinite(y_v))

insert a tab using sed

Lawrence David — Mon, 12 Sep 2011 18:41:14 +0000

if you find that sed isn’t matching \t, the easiest workaround is to not use sed at all.

instead, install ‘gsed’, which can handle tabs.

hide upper ticks in matplotlib figure

Lawrence David — Wed, 31 Aug 2011 17:59:59 +0000

to only show the bottom ticks in a matplotlib figure:

axis_x = ax.xaxis

axis_x.tick_bottom()

get pairwise combinations of a list’s items in python

Lawrence David — Mon, 08 Aug 2011 15:41:28 +0000

use the itertools and random modules in python to get N pairwise combinations of a list’s items:

combo_it = itertools.combinations(my_list,2)
combo_l = list(combo_it)
random.shuffle(combo_l)
pair_l = combo_l[:N]

fix sudo ownership in mac os x

Lawrence David — Fri, 05 Aug 2011 19:55:09 +0000

using sudo was giving me the warning:

sudo: /var/db/sudo owned by uid 501, should be uid 0

to fix:

iMac://usr/bin/sudo chown -R root /private/var/db/sudo

resolve “Nothing can be done for the type” errors when using rpy2

Lawrence David — Wed, 03 Aug 2011 17:51:21 +0000

Importing arrays from numpy to rpy2 can throw the following error:

ValueError: Nothing can be done for the type at the moment.

To resolve, add the following to the top of your Python code:

import rpy2.robjects.numpy2ri

rpy2.robjects.numpy2ri.activate()