Given a character array: In [21]: x = np.array(['a ','bb ','cccc ']) One can remove the whitespace using: In [22]: np.char.strip(x) Out[22]: array(['a', 'bb', 'cccc'], dtype='|S8') but is there a way to also shrink the width of the column to the minimum required size, in the above case |S4? ...
What is the best way to touch two following values in an numpy array? example: npdata = np.array([13,15,20,25]) for i in range( len(npdata) ): print npdata[i] - npdata[i+1] this looks really messed up and additionally needs exception code for the last iteration of the loop. any ideas? Thanks! ...
Okay this is werid, i keep getting the error, randomly. ValueError: matrix must be 2-dimensional So i tracked it down, and cornered it to basically something like this: a_list = [[(1,100) for _ in range(32)] for _ in range(32)] numpy.matrix(a_list) Whats wrong with this? If i print a_list it is clearly a 2d matrix of tuples, howeve...
Hi, the following code comes from the matplotlib gallery: #!/usr/bin/env python from pylab import * x = array([10, 8, 13, 9, 11, 14, 6, 4, 12, 7, 5]) y = array([8.04, 6.95, 7.58, 8.81, 8.33, 9.96, 7.24, 4.26, 10.84, 4.82, 5.68]) I am new to python, and would like to change the content of x and y from an input file. I have two short ...
I want to create a list containing the 3-D coords of a grid of regularly spaced points, each as a 3-element tuple. I'm looking for advice on the most efficient way to do this. In C++ for instance, I simply loop over three nested loops, one for each coordinate. In Matlab, I would probably use the meshgrid function (which would do it in ...
Okay this is probably a really dumb question, however it's really starting to hurt. I have a numpy matrix, and basically I print it out row by row. However I want to make each row be formatted and separated properly. >>> arr = numpy.matrix([[x for x in range(5)] for y in range(5)]) >>> arr matrix([[0, 1, 2, 3, 4], [0, 1, 2, 3,...
What's wrong with this snippet of code? import numpy as np from scipy import stats d = np.arange(10.0) cutoffs = [stats.scoreatpercentile(d, pct) for pct in range(0, 100, 20)] f = lambda x: np.sum(x > cutoffs) fv = np.vectorize(f) # why don't these two lines output the same values? [f(x) for x in d] # => [0, 1, 2, 2, 3, 3, 4, 4, 5, 5]...
I have had that problem before and I couldn't solve it how do I fit a 2d surface z=f(x,y) with a polynomial in numpy (full crossterms). Thanks in advance, Wolfgang ...
Hey, folks. So, I'm doing some Kmeans classification using numpy arrays that are quite sparse-- lots and lots of zeroes. I figured that I'd use scipy's 'sparse' package to reduce the storage overhead, but I'm a little confused about how to create arrays, not matrices. I've gone through this tutorial on how to create sparse matrices: h...
Hello all. Firstly - thanks again for all your help. Sorry not to have accepted the responses to my previous questions as I did not know how the system worked (thanks to Mark for pointing that out!). I have since been back and gratefully acknowledged the kind help I have received. My question: when plotting a graph with a discontinuity/...
I would like to use the sunperf libraries when compiling scipy and numpy. I tried using setupscons.py which seems to check from SUNPERF libraries, but it didnt recognize where mine are: here is a listing of /pkg/linux/SS12/sunstudio12.1 (thats where the sunperf library lives): wkerzend@mosura:/home/wkerzend>ls /pkg/linux/SS12/sunstudio1...
is there a data viewer in python/ipython like the variable editor in MATLAB? ...
Hi, I'm porting an C++ scientific application to python, and as I'm new to python, some problems come to my mind: 1) I'm defining a class that will contain the coordinates (x,y). These values will be accessed several times, but they only will be read after the class instantiation. Is it better to use an tuple or an numpy array, both in...
Hi, is there a numpy-thonic way, e.g. function, to find the 'nearest value' in an array? example: np.find_nearest( array, value ) thanks in advance! ...
Is there a smart and space-efficient symmetric matrix in numpy which automatically (and transparently) fills the position at [j][i] when [i][j] is written to? a = numpy.symmetric((3, 3)) a[0][1] = 1 a[1][0] == a[0][1] # True print a # [[0 1 0], [1 0 0], [0 0 0]] assert numpy.all(a == a.T) # for any symmetric matrix An automatic Hermi...
I recently asked about trying to optimise a Python loop for a scientific application, and received an excellent, smart way of recoding it within NumPy which reduced execution time by a factor of around 100 for me! However, calculation of the B value is actually nested within a few other loops, because it is evaluated at a regular grid o...
I swear this should be so easy... Why is it not? :( In fact, I want to combine 2 parts of the same array to make a complex array: Data[:,:,:,0] , Data[:,:,:,1] These don't work: x = np.complex(Data[:,:,:,0], Data[:,:,:,1]) x = complex(Data[:,:,:,0], Data[:,:,:,1]) Am I missing something? Does numpy not like performing array functi...
Let's say I have an array of zeros: a = numpy.zeros(1000) I then introduce some repetitive 'events': a[range(0, 1000, 30)] = 1 Question is, how do I detect the 'signal' there? Because it's far from the ideal signal if I do the 'regular' FFT I don't get a clear indication of where my 'true' signal is: f = abs(numpy.fft.rfft(a)) Is t...
I have a fairly simple math operation I'd like to perform on a array. Let me write out the example: A = numpy.ndarray((255, 255, 3), dtype=numpy.single) # .. for i in range(A.shape[0]): for j in range(A.shape[1]): x = simple_func1(i) y = simple_func2(j) A[i, j] = (alpha * x * y + beta * x**2 + gamma * y**2, 1...
I have a problem where depending on the result of a random coin flip, I have to sample a random starting position from a string. If the sampling of this random position is uniform over the string, I thought of two approaches to do it: one using multinomial from numpy.random, the other using the simple randint function of Python standard...