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Inverse Distance Weighted (IDW) Interpolation with Python

changed 20 Oct: this class Invdisttree combines inverse-distance weighting and scipy.spatial.KDTree. Forget the original brute-force answer; this is imho the method of choice for scattered-data interpolation. “”” invdisttree.py: inverse-distance-weighted interpolation using KDTree fast, solid, local “”” from __future__ import division import numpy as np from scipy.spatial import cKDTree as KDTree # http://docs.scipy.org/doc/scipy/reference/spatial.html __date__ = “2010-11-09 … Read more

Meaning of inter_op_parallelism_threads and intra_op_parallelism_threads

The inter_op_parallelism_threads and intra_op_parallelism_threads options are documented in the source of the tf.ConfigProto protocol buffer. These options configure two thread pools used by TensorFlow to parallelize execution, as the comments describe: // The execution of an individual op (for some op types) can be // parallelized on a pool of intra_op_parallelism_threads. // 0 means the … Read more

How to “properly” print a list?

In Python 2: mylist = [‘x’, 3, ‘b’] print ‘[%s]’ % ‘, ‘.join(map(str, mylist)) In Python 3 (where print is a builtin function and not a syntax feature anymore): mylist = [‘x’, 3, ‘b’] print(‘[%s]’ % ‘, ‘.join(map(str, mylist))) Both return: [x, 3, b] This is using the map() function to call str for each … Read more

How to set env variable in Jupyter notebook

To set an env variable in a jupyter notebook, just use a % magic commands, either %env or %set_env, e.g., %env MY_VAR=MY_VALUE or %env MY_VAR MY_VALUE. (Use %env by itself to print out current environmental variables.) See: http://ipython.readthedocs.io/en/stable/interactive/magics.html

Debugging (displaying) SQL command sent to the db by SQLAlchemy

In addition to echo parameter of create_engine() there is a more flexible way: configuring logging to echo engine statements: import logging logging.basicConfig() logging.getLogger(‘sqlalchemy.engine’).setLevel(logging.INFO) See Configuring Logging section of documentation for more information.

Pythonic way to check if a file exists? [duplicate]

To check if a path is an existing file: os.path.isfile(path) Return True if path is an existing regular file. This follows symbolic links, so both islink() and isfile() can be true for the same path.

Using Colormaps to set color of line in matplotlib

The error you are receiving is due to how you define jet. You are creating the base class Colormap with the name ‘jet’, but this is very different from getting the default definition of the ‘jet’ colormap. This base class should never be created directly, and only the subclasses should be instantiated. What you’ve found … Read more

A very simple multithreading parallel URL fetching (without queue)

Simplifying your original version as far as possible: import threading import urllib2 import time start = time.time() urls = [“http://www.google.com”, “http://www.apple.com”, “http://www.microsoft.com”, “http://www.amazon.com”, “http://www.facebook.com”] def fetch_url(url): urlHandler = urllib2.urlopen(url) html = urlHandler.read() print “‘%s\’ fetched in %ss” % (url, (time.time() – start)) threads = [threading.Thread(target=fetch_url, args=(url,)) for url in urls] for thread in threads: thread.start() … Read more

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How to make scipy.interpolate give an extrapolated result beyond the input range?

As of SciPy version 0.17.0, there is a new option for scipy.interpolate.interp1d that allows extrapolation. Simply set fill_value=”extrapolate” in the call. Modifying your code in this way gives: import numpy as np from scipy import interpolate x = np.arange(0,10) y = np.exp(-x/3.0) f = interpolate.interp1d(x, y, fill_value=”extrapolate”) print f(9) print f(11) and the output is: … Read more