thearn’s gists

thearn / fft_convolution.py

Last active November 18, 2023 09:47

1D and 2D FFT-based convolution functions in Python, using numpy.fft

	from numpy.fft import fft, ifft, fft2, ifft2, fftshift
	import numpy as np

	def fft_convolve2d(x,y):
	""" 2D convolution, using FFT"""
	fr = fft2(x)
	fr2 = fft2(np.flipud(np.fliplr(y)))
	m,n = fr.shape
	cc = np.real(ifft2(fr*fr2))
	cc = np.roll(cc, -m/2+1,axis=0)

thearn / svd_approximate.py

Last active January 8, 2024 20:25

Function to generate an SVD low-rank approximation of a matrix, using numpy.linalg.svd. Can be used as a form of compression, or to reduce the condition number of a matrix.

	import numpy as np


	def low_rank_approx(SVD=None, A=None, r=1):
	"""
	Computes an r-rank approximation of a matrix
	given the component u, s, and v of it's SVD

	Requires: numpy
	"""

thearn / gzip_pickle.py

Created April 20, 2013 00:57

Functions for saving and loading python objects using pickle with gzip compression.

	import pickle
	import gzip

	def save(object, filename, protocol = 0):
	"""Saves a compressed object to disk
	"""
	file = gzip.GzipFile(filename, 'wb')
	file.write(pickle.dumps(object, protocol))
	file.close()

thearn / pprocess_test.py

Created April 20, 2013 01:07

An experiment with pprocess

	import pprocess
	import time
	import numpy as np

	# Define a function to parallelize:
	def takeuptime(x):
	"""A function to waste CPU cycles"""
	time.sleep(0.1)
	return x[-1]

thearn / brew.py

Last active December 16, 2015 10:59

A simple command-line app to help profile homebrew'ed beer. User inputs starting temperature, starting original gravity, and the app will compute and print temperature-adjusted original gravity and max potential ABV. Final (post-fermentation) temperature and specific-gravity can also be input to calculate effective ABV, calories per serving, and…

	def adjust(t, og):
	t2 = 1.34722124e-4 * t
	t3 = 2.04052596e-6 * t ** 2
	t4 = 2.32820948e-9 * t ** 3
	sgcf = 1.00130346 - t2 + t3 - t4
	sg = og * sgcf
	adjusted_og = sg
	OE = -668.962 + 1262.45 * sg - 776.43 * sg * sg + 182.94 * sg * sg * sg
	abv_max = (sg - 1) * 105 * 1.25

thearn / fft_series.py

Last active December 16, 2015 11:49

Class for buffering an incoming data series and computing an FFT

	import numpy as np
	import time


	class bandProcess(object):

	"""
	Component to isolate specific frequency bands
	"""

thearn / ip.py

Last active December 16, 2015 11:59

A python code to determine a computer's external IP address, which is then written to a text file. Run from a dropbox folder (or something similar), this provides a very simple way to determine your home's dynamic external IP address remotely.

	import urllib
	import re
	import time
	import datetime


	def get_ip():
	group = re.compile(u'(?P<ip>\d+\.\d+\.\d+\.\d+)').search(
	urllib.URLopener().open('http://jsonip.com/').read()).groupdict()
	return group['ip']

thearn / opencv-python-ipcam.py

Last active January 12, 2023 17:01

python-opencv ip camera example

	import base64
	import time
	import urllib2

	import cv2
	import numpy as np


	"""
	Examples of objects for image frame aquisition from both IP and

thearn / microscope.py

Last active December 17, 2015 09:29

Code to operate USB microscope, with selectable contrast correction

	import cv2

	# Create object to read images from camera 0
	cam = cv2.VideoCapture(1)


	class imgSlice(object):

	def __init__(self):
	self.x = 0

thearn / capture.py

Created June 15, 2013 21:31

Screen capture using python PIL

	import time
	import Image
	import ImageGrab

	while True:
	time.sleep(0.5)
	t = str(time.time()).replace('.','-')
	tt = time.time()
	img=ImageGrab.grab()
	img = img.resize((800,600))

Tristan Hearn thearn