from the desk of stinkpot

match tab in sed

Lawrence David — Thu, 17 May 2012 13:07:38 +0000

to replace a tab in sed:

sed ‘s///’

where is you typing CTRL-V followed by pressing TAB (thanks to atoztoa!).

alternatively:

sed ‘s/\\\t//’

use csv to write out data in python

Lawrence David — Thu, 01 Mar 2012 19:46:30 +0000

the csv module is a helpful module for writing out data in python.

here’s how to write out data:

import csv

….

color_l = ['red','green','blue']
text_l = ['roses','turtles','water']
color_f = open(foo.bar,’w')
header_l=['text','color']
csv_o = csv.DictWriter(color_f,delimiter=’;',fieldnames=header_l)
csv_o.writeheader()
row_l = [{'text':a,'color':b} for a,b in zip(text_l,color_l)]
csv_o.writerows(row_l)
color_f.close()

ftp problems with wordpress automatic update

Lawrence David — Thu, 01 Mar 2012 05:00:38 +0000

i was getting this error: “There was an error connecting to the server, Please verify the settings are correct.” when trying to use wordpress’ automatic update function.

turns out the problem was that my ftp server was disallowing local connections.

to fix, i had to uncomment the line: “local_enable=YES” from /etc/vsftpd.conf and restart the vsftpd server.

then, i noticed a new problem while updating: “Could not create directory.”

the solution: uncomment “write_enable=YES” from /etc/vsftpd.conf and restart again.

finally, i eliminated “Could not copy files.” errors by chown’ing all files and directories in my wordpress directory to be owned by the ftp user specified in the update login.

hide the axis frame in matplotlib

Lawrence David — Mon, 27 Feb 2012 22:03:58 +0000

to hide the axis bordering a figure:

fig, ax = pylab.subplots()

ax.set_frame_on(False)

remove axis labels in matplotlib

Lawrence David — Mon, 27 Feb 2012 22:02:57 +0000

to remove the labels of the x-axis:

ax.get_xaxis().set_ticks([])

to remove the labels of the y-axis:

ax.get_yaxis().set_ticks([])

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))