How to turn a vector into a matrix in R?

Just use matrix: matrix(vec,nrow = 7,ncol = 7) One advantage of using matrix rather than simply altering the dimension attribute as Gavin points out, is that you can specify whether the matrix is filled by row or column using the byrow argument in matrix.

Recommendation for C# Matrix Library [closed]

Math.NET Numerics is very nice, if it supports the operations you want. The older Math.Net Iridium still supports more options. Also, dnAnalytics is quite nice, but no longer being developed. (It, as well as Iridium, are being merged into Math.NET Numerics.) On the commercial side, there are some very good, robust options. The Extreme Optimization … Read more

Numpy ‘smart’ symmetric matrix

If you can afford to symmetrize the matrix just before doing calculations, the following should be reasonably fast: def symmetrize(a): “”” Return a symmetrized version of NumPy array a. Values 0 are replaced by the array value at the symmetric position (with respect to the diagonal), i.e. if a_ij = 0, then the returned array … Read more

Inverse of a matrix using numpy

The I attribute only exists on matrix objects, not ndarrays. You can use numpy.linalg.inv to invert arrays: inverse = numpy.linalg.inv(x) Note that the way you’re generating matrices, not all of them will be invertible. You will either need to change the way you’re generating matrices, or skip the ones that aren’t invertible. try: inverse = … Read more

How do I multiply matrices in PyTorch?

Use torch.mm: torch.mm(a, b) torch.dot() behaves differently to np.dot(). There’s been some discussion about what would be desirable here. Specifically, torch.dot() treats both a and b as 1D vectors (irrespective of their original shape) and computes their inner product. The error is thrown because this behaviour makes your a a vector of length 6 and … Read more

Android: How to rotate a bitmap on a center point

I hope the following sequence of code will help you: Bitmap targetBitmap = Bitmap.createBitmap(targetWidth, targetHeight, config); Canvas canvas = new Canvas(targetBitmap); Matrix matrix = new Matrix(); matrix.setRotate(mRotation,source.getWidth()/2,source.getHeight()/2); canvas.drawBitmap(source, matrix, new Paint()); If you check the following method from ~frameworks\base\graphics\java\android\graphics\Bitmap.java public static Bitmap createBitmap(Bitmap source, int x, int y, int width, int height, Matrix m, boolean … Read more

Scale and mirror SVG object

To apply both scale and flip, just list both in your transform: transform=”scale(2,2) scale(-1,1)” Or simply combine the values: transform=”scale(-2,2)” Of course, the issue you have with negative scales is that the objects get flipped across the origin (top left) of the SVG, so they can go off the edge of the document. You need … Read more