I have two arrays x and y. Here I’ve plotted them using Matplotlib and found the global minima using this simple logic. Here is the output that I’m getting: After that I’ve smoothen the graph BSpline Now my position of the global minima has changed and that simple logic will not work here. I…
Tag: numpy
Fill up column based on condition goes wrong
I am trying to fill a column based on condition but something goes wrong. So I am expecting if it is not 2017 there should be a no. But yet the years 2019 and 2020 also get filled up with yes. Does anyone know what went wrong? Answer Use Series.between instead & for bitwise AND, for chain by bitwise OR
colors are wrong numpy array for pillow image when I use txt
firstly I am transforming an image into numpy array and writing it to a text file and this part is working the problem is when i copy the txt content and dynamically paste it as vector and display the image. the colors are showing wrong. enter image description here enter image description here ` ` I need to …
Losing cell formats when accessing rows
In some circumstances the format (int, float, etc) of a cell is lost when accessing via its row. In that example the first column has integers and the second floats. But the 111 is converted into 111.0. The output I would expect is like this I have an idea why this happens. But IMHO this isn’t user frie…
Generate random binary matrix constrained to no null row
I want to generate a random binary matrix, so I’m using W=np.random.binomial(1, p, (n,n)). It works fine, but I want a constraint that no row is just of 0s. I create the following function: It also works fine, but it seems to me too inefficient. Is there a faster way to create this constraint? Answer Wh…
How can I sort 2d array includes only string characters in Python?
There is an array as below; I used the following codes to sort this array by the second column but without success. Is there anyone to help? Answer np.take(x, x[:, 1].astype(int).argsort(), 0) You may just cast the values for sorting. The overall result of you np.take() will remain as strings.
Get all permutations of bool array
I need all permutations of a bool array, the following code is inefficient, but does what I want: However it is inefficient and fails for long arrays. Is there a more efficent implementation? Answer What about sampling the combinations of indices of the True values: Output:
Centering matrix
I want to write a function for centering an input data matrix by multiplying it with the centering matrix. The function shall subtract the row-wise mean from the input. My code: But I get a wrong result matrix, it is not centered. Thanks! Answer The centering matrix is Here is a list of issues in your origina…
Cholesky factorisation not lower triangular
I am building a cholesky factorisation algorthim as proposed from the book: Linear Algebra and Optimisation for Machine Learning They provide the following algorthim: I have attempted this with python with the following algorithm: When testing this on a matrix I get upper triangular as opposed to lower triang…
Deleting multiple elements in a list – with a list of item locations
I have two lists. List1 is the list of items I am trying to format List2 is a list of item locations in List1 that I need to remove (condensing duplicates) The issue seems to be that it first removes the first location (9) and then removes the second (16) after…instead of doing them simultaneously. Afte…