April 29, 2017, 8:29 p.m.

Numpy - useful functionalities

Importing an array in python



>>> from numpy import *
>>>
>>> data = loadtxt("myfile.txt")                       # myfile.txt contains 4 columns of numbers
>>> t,z = data[:,0], data[:,3]                         # data is 2D numpy array
>>>
>>> t,x,y,z = loadtxt("myfile.txt", unpack=True)                  # to unpack all columns
>>> t,z = loadtxt("myfile.txt", usecols = (0,3), unpack=True)     # to select just a few columns
>>> data = loadtxt("myfile.txt", skiprows = 7)                    # to skip 7 rows from top of file
>>> data = loadtxt("myfile.txt", comments = '!')                  # use '!' as comment char instead of '#'
>>> data = loadtxt("myfile.txt", delimiter=';')                   # use ';' as column separator instead of whitespace
>>> data = loadtxt("myfile.txt", dtype = int)                     # file contains integers instead of floats

 

 

cheatsheet: 

https://s3.amazonaws.com/assets.datacamp.com/blog_assets/PythonForDataScience.pdf