suppose I have a python list or a python 1-d array (represented in numpy). assume that there is a contiguous stretch of elements how can I find the start and end coordinates (i.e. indices) of the stretch of non-zeros in this list or array? for example, a = [0, 0, 0, 0, 1, 2, 3, 4] nonzero_coords(a) should return [4, 7]. for: b = ...
Hi folks, I'm looking for a way to read in c++ a text file containing numpy arrays and put the data into vector< vector< ... > > , can anyone help me out please ? Thanks a lot. Archy EDIT: format of the text file [[[ 0 1] [ 2 3] [ 4 5] [ 6 7] [ 8 9]] [[10 11] [12 13] [14 15] [16 17] [18 19]] [[20 21] [22 23] [24 25] [26 27] [28 29]] ...
I have a 3d array, a, of shape say a.shape = (10, 10, 10) When slicing, the dimensions are squeezed automatically i.e. a[:,:,5].shape = (10, 10) I'd like to preserve the number of dimensions but also ensure that the dimension that was squeezed is the one that shows 1 i.e. a[:,:,5].shape = (10, 10, 1) I have thought of re-casting the...
Often, I am building an array by iterating through some data, e.g.: my_array = [] for n in range(1000): # do operation, get value my_array.append(value) # cast to array my_array = array(my_array) I find that I have to first build a list and then cast it (using "array") to an array. Is there a way around these? all these casting c...
I'd like to convert a list of record arrays -- dtype is (uint32, float32) -- into a numpy array of dtype np.object: X = np.array(instances, dtype = np.object) where instances is a list of arrays with data type np.dtype([('f0', '<u4'), ('f1', '<f4')]). However, the above statement results in an array whose elements are also of type n...
Hello, I am new to python, apologies if this has been asked already. Using python and numpy, I am trying to gather data across many netcdf files into a single array by iteratively calling append(). Naively, I am trying to do something like this: from numpy import * from pupynere import netcdf_file x = array([]) y = [...some list of ...
I have a numpy array with positive and negative values in. a = array([1,1,-1,-2,-3,4,5]) I want to create another array which contains a value at each index where a sign change occurs (For example, if the current element is positive and the previous element is negative and vice versa). For the array above, I would expect to get the ...
I added the legend this way: leg = fig.legend((l0,l1,l2,l3,l4,l5,l6), ('0 Cl : r2, slope, origin', '1 Cl :'+str(r1b)+' , '+str(m1)+' , '+str(b1), '2 Cl :'+str(r2b)+' , '+str(m2)+' , '+str(b2), '3 Cl :'+str(r3b)+' , '+str(m3)+' , '+str(b3), '4 Cl :'+str(r4b)+' , '+str(m4)+' , '+str(b4), '5 Cl :'+str(r5b)+...
I have created an array thusly: import numpy as np data = np.zeros( (512,512,3), dtype=np.uint8) data[256,256] = [255,0,0] What I want this to do is display a single red dot in the center of a 512x512 image. (At least to begin with... I think I can figure out the rest from there) ...
Hello all, I've got a CSV file with a format that looks like this: "FieldName1", "FieldName2", "FieldName3", "FieldName4" "04/13/2010 14:45:07.008", "7.59484916392", "10", "6.552373" "04/13/2010 14:45:22.010", "6.55478493312", "9", "3.5378543" ... Note that there are double quote characters at the start and end of each line ...
I have a data.frame in R. It contains a lot of data : gene expression levels from many (125) arrays. I'd like the data in Python, due mostly to my incompetence in R and the fact that this was supposed to be a 30 minute job. I would like the following code to work. To understand this code, know that the variable path contains the full pa...
I'm trying to vectorize a for loop that I have inside of a class method. The for loop has the following form: it iterates through a bunch of points and depending on whether a certain variable (called "self.condition_met" below) is true, calls a pair of functions on the point, and adds the result to a list. Each point here is an element i...
I am using SWIG to pass numpy arrays from Python to C++ code: %include "numpy.i" %init %{ import_array(); %} %apply (float* INPLACE_ARRAY1, int DIM1) {(float* data, int n)}; class Class { public: void test(float* data, int n) { //... } }; and in Python: c = Class() a = zeros(5) c.test(a) This works, but how can I pa...
hi there, are there any way to create an object form any class inside a numpy array?. Something like: a = zeros(4) for i in range(4): a[i]=Register() Thanks ...
Hi together, I have a scipy.sparse.dok_matrix (dimensions m x n), wanting to add a flat numpy-array with length m. for col in xrange(n): dense_array = ... dok_matrix[:,col] = dense_array However, this code raises an Exception in dok_matrix.__setitem__ when it tries to delete a non existing key (del self[(i,j)]). So, for now ...
I am fitting a Gaussian kernel density estimator to a variable that is the difference of two vectors, called "diff", as follows: gaussian_kde_covfact(diff, smoothing_param) -- where gaussian_kde_covfact is defined as: class gaussian_kde_covfact(stats.gaussian_kde): def __init__(self, dataset, covfact = 'scotts'): self.covfac...
I have two arrays and I take their logs. When I do that and try to plot their scatter plot, I get this error: File "/Library/Python/2.6/site-packages/matplotlib-1.0.svn_r7892-py2.6-macosx-10.6-universal.egg/matplotlib/pyplot.py", line 2192, in scatter ret = ax.scatter(x, y, s, c, marker, cmap, norm, vmin, vmax, alpha, linewidths, ...
I have an array with two columns in numpy. For example: a = array([[1, 5, nan, 6], [10, 6, 6, nan]]) a = transpose(a) I want to efficiently iterate through the two columns, a[:, 0] and a[:, 1] and remove any pairs that meet a certain condition, in this case if they are NaN. The obvious way I can think of is: new_a = [] fo...
I am trying to plot the following numbers on a log scale as a scatter plot in matplotlib. Both the quantities on the x and y axes have very different scales, and one of the variables has a huge dynamic range (nearly 0 to 12 million roughly) while the other is between nearly 0 and 2. I think it might be good to plot both on a log scale....
Hello! The following code does not work. It seems that the R warning message raises a python error. # enable use of python objects in rpy2 import rpy2.robjects.numpy2ri import numpy as np from rpy2.robjects import r # create an example array a = np.array([[5,2,5],[3,7,8]]) # this line leads to a warning message, which in turn raises ...