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 want to know how I can
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 get the
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 friendly. Can I
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 When the matrix is large,
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 original formulation: np.ones(n).T is
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 triangular. Where was I mistaken? Answer You don’t even need to look
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. After it removes 9, the