one-liners in linux and more

import numpy as np

dat=[some array of numbers]

np.percentile(dat,10)

np.percentile(dat, 90)

np.mean(dat)

np.median(dat)

To compile a C or program (extension .c), use the command 

gcc programname.c

Use the -o option to specify the output name

gcc -o newname programname.c

If the extension is .cpp, then it is a C++ program and you can use

g++ programname.cpp

All parameters are

numpy.loadtxt(fname, dtype=<type 'float'>, comments='#', delimiter=None, converters=None, skiprows=0, usecols=None, unpack=False, ndmin=0)

fname is the filename ‘./sample.txt’), where the text needs to be columns of the same length, ie no missing values (for missing values look into genfromtxt)

To get the format XXX.XX for a column of numbers, try:

awk ‘{printf “%3.2f\n”, $1}’

for the double quote “ awk ‘BEGIN{print “\””}’

surprisingly easy :) and listed in the manual for ‘sort’ command (>> man sort)

as an example, say you have a commas as the FS. to sort, use the option

sort --field-separator=,

One use of argparse in Python that I use often is writing a script that takes an input from the command line. This way, you can run the script iteratively over multiple files. 

Some good/common things to import on python

Given a text file that formed like a complete matrix, you can use python and numpy to get the transpose of it as needed by using the following lines:

use the command to bring up the ipython gui

ipython notebook

and use the command to see the figure without on the same page of results

use the command 

makecpt -T1/3/0.5 -Z > ppp.cpt

to create a color bar from value of 1 to value of 3 in 0.5 intervals stored in a file called ppp.cpt. This ppp.cpt file is used in the script that makes the plot within the line

cpt=“ppp.cpt”

An example (as of the day this is posted) is in the space I have on hydra, I have a file called .plot.temp.scr -- it is a script that was originally used to create a plot of temperature. I use the command

./plt.temp.scr precip.climatology

Useful for when figures/graphics are not supported and you want to save the figure directly without it popping up

import matplotlib as mpl import matplotlib.pyplot as plt mpl.use(’Agg’)

<<code>>

Use awk to find the minimum and maximum value of column one in some file ‘data.txt’