Questions tagged [numpy]

NumPy stands out among the numerous Python modules for its ability to enhance the handling of extensive multidimensional arrays and matrices. In addition, it provides a vast collection of advanced mathematical functions tailored specifically for efficient manipulation of these arrays.

Tips for converting basic geometric figures into numpy arrays

Is there a way to create a 200x200 numpy array containing a circle with a radius of 80, centered at coordinates (100,100), and a stroke width of 3 pixels in Python 2.7 without using file operations? I am looking for a solution that utilizes geometry or i ...

Expanding the dimensions of both 3D and 2D array

Currently, I am faced with a challenge involving a 3D array of shape (3, 4, 3) and a 2D array of shape (3, 3). My objective is to multiply these arrays in such a way that the ith element of the resulting 3D array corresponds to the product of the ith eleme ...

Combining a 2D array with a 3D array to create a larger 3D array with an expanded third dimension

I am facing a challenge with two arrays in my coding project. Array A represents 3124 models with 5 reference parameters, while array B represents 3124 models, 19 time steps per model, and 12288 temperature field data points per time step. My goal is to a ...

Methods for converting camera calibration parameters stored in a .mat file from Matlab into numpy arrays in Python

After successfully calibrating the camera using Matlab 2019a, I saved all the camera parameters in a variable called cameraParams. However, I am specifically interested in extracting the Intrinsic matrix and distortion coefficients from this data. How c ...

What are the ideal scenarios for utilizing pandas series, numpy ndarrays, or basic python dictionaries?

Being new to Python and its libraries like numpy and pandas, I have come across a plethora of documentation explaining how numpy ndarrays, pandas series, and python dictionaries operate. Despite this, my lack of experience with Python has made it challeng ...

Error encountered when attempting to convert 3D numpy array into mesh: RuntimeError - Unable to locate a surface with the specified iso value

I have developed a deep learning model to segment CT scans. The process involves reading the scan as a .nrrd file in python and converting it to a numpy array for training the model. After successfully predicting a numpy array with the model, I encounter ...

Encountering a value error when using enc.transform with a OneHotEncoder set to sparse_output=False in pandas

My dataset named temp is a timeseries data with 4 columns: Date, Minutes, Issues, Reason no. In this dataset: temp['REASON NO'].value_counts() produces the following output: R13 158 R14 123 R4 101 R7 81 R2 40 R3 35 R5 31 R8 ...

How can consecutive values be identified in a 3D numpy array in Python without relying on the groupby function?

Consider having a 3D numpy array like the one below: matrices= numpy.array([[[1, 0, 0], #Level 0 [1, 1, 1], [0, 1, 1]], [[0, 1, 0], #Level 1 [1, 1, 0], [0, 0, 0]], [[0, 0, ...

Obtaining a series of coordinates from a Numpy array

I have a 100x100x100 numpy array that represents a 3D volume composed of 2D slices. My goal is to conduct cross correlation on the object in this volume across multiple volumes using a template derived from the volume with the best signal-to-noise ratio. ...

Is there a way to print a particular value within a matrix using Python, specifically with the help of numpy?

I am facing an issue with a code snippet that is supposed to generate a zero matrix based on a given size (m x n). However, my goal is to extract a specific value from a particular location within that matrix. Despite trying numerous approaches, I have not ...

Is there a potential issue with infinity or excessively large values?

I've encountered an issue while training a neural network using keras and tensorflow. Typically, I replace -np.inf and np.inf values with np.nan in order to clean up erroneous data before proceeding with operations such as: Data.replace([np.inf, -np. ...

Upon attempting to import Numpy, an AttributeError is raised: 'module' object does not possess the attribute 'core'

import numpy as np File "/home/anirrudh/.virtualenvs/ml4t2/local/lib/python2.7/site-packages/numpy/__init__.py", line 180, in <module> from . import add_newdocs File "/home/anirrudh/.virtualenvs/ml4t2/local/lib/python2.7/site-packages/numpy/a ...

Separate information into columns and save it as a two-dimensional array

Below is the data that I am working with: 49907 87063 42003 51519 21301 46100 97578 26010 52364 86618 25783 71775 1617 29096 2662 47428 74888 54550 17182 35976 86973 5323 ...... My goal is to iterate through it using for line in file. I would like to s ...

Developing an uncomplicated password decryption tool utilizing numpy arrays

Is there a way to enhance my password cracker function by utilizing numpy arrays instead of for-loops? How can I prevent the error shown in the code image while implementing improvements to my cracker function? Here is the code snippet for reference I a ...

Determining the count of series using Python's Pandas

I needed to determine the number of series contained within a specific dataset. The count of time-series information was required for analysis. https://i.stack.imgur.com/VHQvw.png Within this context, I wanted users to select how they wished to analyze ...

Combine pandas dataframes by matching date intervals and values

I am searching for a way to streamline the process of reconciling bank transactions. In this scenario, there are two tables - one from the bank and one from the system. However, there is a delay of a few days in the transactions recorded in the system tabl ...

Tips for Multiplying Matrix Values by a Constant when a Certain Condition is Satisfied

I am faced with a challenge in Python. I have a matrix that needs to be returned with a specific rule applied. The rule states that if there are any elements in the matrix that are less than zero, their values must be multiplied by a constant before return ...

Exploring Numpy Arrays through Loops and Searches

Currently, I am looping through a numpy array and performing a search operation which is taking approximately 60 seconds to complete for arrays (npArray1 and npArray2 in the sample code) containing around 300,000 values. To elaborate, I am seeking the ind ...

Generate a new dataframe by parsing and splitting the values from each row in the original dataframe

I need help transforming comma-delimited strings in a given pandas dataframe into separate rows. For example: COLUMN_1 COLUMN_2 COLUMN_3 "Marvel" "Hulk, Thor, Ironman" "1,7,8" "DC" ...

Tips for managing memory overflow when working with Pivot tables

I am faced with two medium-sized datasets that are structured as follows: books_df.head() ISBN Book-Title Book-Author 0 0195153448 Classical Mythology Mark P. O. Morford 1 0002005018 Clara Callan Richard Bruce Wright 2 0060973129 ...

Creating a scatter plot with separate data points and exploring the method to use a colormap for colorizing the points

My aim with matplotlib is to create a scatter plot where both markers and colors vary. import matplotlib.pyplot as plt import numpy as np markers = np.array(["1","2","3","4","+",">"]) # Sample Data x = np.array([0, 2, 3, 4, 0, 1, 5, 6, 7, 8]) y = np.a ...

What is the method for sorting an array in numpy while keeping the same order as another array?

Consider two numpy arrays a and w, both with the same shape (d1,d2,..,dk,N). We can view them as N samples with shape (d1,d2,...,dk). Now, the goal is to sort arrays a and w along a's last axis. For instance, if a and w have a shape of (2,4): a = [[ ...

Padding an array with zeros along a specific axis

I need to pad the following array: [[1, 2] [3, 4]] so that it becomes: [[0, 0, 0] [0, 1, 2] [0, 3, 4]] I can easily achieve this with vstack and hsrack when working with a 2D input. However, I encounter an issue when adding an extra dimension to re ...

Populating a two-dimensional grid to ensure adjacent values are distinct from each other

I am curious to estimate the worst-case scenario of an algorithm that relies on the number of iterations based on how many pixels in an image have neighboring pixels with differing values. Assuming the image is grayscale, I am seeking a method to create an ...

Error detected in Numpy ndarray min/max function

It seems like I might be making a mistake somewhere. I'm currently working on a project in Pycharm and when using the ndarray.max() function, a notification popped up saying that initial was undefined (parameter 'initial' unfilled). Checking the documentat ...

Numpy Matrix Computation

I need help with using NumPy broadcasting to calculate Rij = Aij x Bji/Cij. I also want to include an exception if the matrices are not the same size (n × n). Not sure if my approach is correct or if I should be performing element-wise or matrix-wise ope ...

Generating a new column by applying a condition to existing column values

In my dataset, there is a column labeled "brand" with different values: brand Brand1 Brand2 Brand3 data.brand = data.brand.astype(str) data.brand = data.brand.replace(r'^\s*$', np.nan, regex=True) data['branded'] ...

creating a parabolic shape within a section of a cyclical wave using the numpy library

A repetitive signal with slight variations in each cycle occurs approximately every second. Each cycle differs slightly in duration and content within certain parameters. The signal data consists of a thousand x,y coordinates per second, with a small but s ...

Ways to calculate the sum of values in a column and then group them together

I am looking to obtain the count of OK & NOK for each ITCD & Indicateur RDV, using a sample from my table: _ITCD_ | _Indicateur RDV_ | Week | Workers OK OK 41 John OK NOK 41 John NOK NOK ...

Leveraging array indexing for implementing a 2D array operation on a 3D array

I have developed a function that takes a set of randomized cartesian coordinates and outputs the subset that falls within a specific spatial domain. For example: grid = np.ones((5,5)) grid = np.lib.pad(grid, ((10,10), (10,10)), 'constant') >> np.sh ...

Tips for creating curved corners on a polygon using given x and y coordinates

Is there a way to draw a polygon from X, Y coordinates with rounded corners using the points I have? Below is my current code, but I am open to suggestions if there is another library that may work better. Displayed below is my output image generated by ...

Generating aliases for numpy functions

Using a=np.square is a way to create an alias for the pow(x,2) function. Just like that, I am looking to create an alias for the pow(x,3) function as well. a = np.power(x2=3) But it appears that this method isn't working as intended. Is there any ...

Performing mathematical operations using matrices that have lists as their data values

I have multiple sets of data arranged in columns within a dataframe, totaling nine lists in all. My objective is to perform matrix operations on every row present across these columns. To illustrate, consider the following operation: O(G) = trace(G*transp ...

What steps are involved in creating a continuous time high/low pass filter in Python?

My application receives incoming signals with a fixed frequency, and I am trying to implement a filter for this signal without having to save N timesteps. I want to update my current state with each new observation, similar to a one-dimensional Kalman filt ...

Finding the maximum value across all axes except for the first one

Looking for a way to find the argmax over all axes except the first in a numpy array. I have come up with a solution, but I'm curious if there is a more efficient method. import numpy as np def argmax(array): ## Argmax along all axes except the ...

python Efficiently load zipfile data into a numpy array

I am searching for a solution to efficiently read a zipfile into memory and extract its contents into a numpy array with numpy datatypes. The challenge lies in the fact that these files are large in size and there are numerous of them, making speed a cruci ...

Guide to including only zeros and keeping non-zero values unchanged in Python's OpenCV

I need assistance with adding a shifted version of an image to the original, while ensuring zeros are left intact. I attempted the following code but encountered some issues. Any help is greatly appreciated! import cv2 import numpy as np #Given image i ...

Gradient and arrow plots

from scipy import * import matplotlib.pyplot as plt def plot_elines(x_grid, y_grid, potential, field): fig, ax = plt.subplots(figsize=(13, 13)) im_cs = ax.contour(x_grid, y_grid, potential, 18, cmap='inferno') plt.clabel(im_cs, inli ...

How to calculate the logarithm of a positive number in Python and deal with the result of negative

Displayed below is an image: HI00008918.png The goal is to implement a logarithmic function (f(x) = (1/a)*log(x + 1), with the value of a = 0.01), on the image... Here is the code segment: import numpy as np import matplotlib.pyplot as plt import skimage ...

Creating visualizations with varying array lengths on a single Pandas plot

a and b represent the datetime indexes for two sets of values, A Values and B Values, respectively. The size of A Values is larger than that of B Values. I am looking to create a code snippet where both sets are plotted on the same graph with numpy arrays ...

What is the reason behind numpy.angle() not being a universal function (ufunc)?

What makes numpy.angle() different from other numpy universal functions (ufuncs)? Although it seems to meet the criteria outlined in the numpy documentation, why is it not officially categorized as a ufunc? I initially speculated that its conversion of c ...

Best practices for setting up divisi2 on python 2.7?

Struggling to get divisi2 up and running on Anaconda Python 2.7. I've gone through every method at my disposal: pip, easy_install, even installing from the Python source, but no luck. I’ve included a snippet of the process below. I apologize for the l ...

Encoding a list of categories as strings for creating Pandas dummies

I am working with a dataframe structured like this: id amenities ... 1 "TV,Internet,Shower,..." ... 2 "TV,Hot tub,Internet,..." ... 3 "Internet,Heating,Shower..." ... ... My goal is to split the string by comm ...

"Expand" the dataset and populate with zeroes

I am looking to transform the data frame provided below: ID X Var1 Var2 Var3 A 1 52 16 17 A 2 73 0 20 A 3 60 42 16 A 4 15 87 73 A 5 0 18 63 B 1 66 42 0 B 3 13 28 64 B 4 ...

Using Python's Matplotlib library to display an image with shifted xlabel numbers

Is there a way to adjust the x and y axis label numbers by adding +2? In other words, I have created this image but I need the label numbers to start with 2: https://i.stack.imgur.com/LeHjF.png Here is the code I used: jacaardMatrix = 1.6628873771730914 ...

Tips for efficiently looping through and making changes to pixel arrays using numpy

As a newcomer to Python and its libraries, I am exploring the conversion of HDR images to RGBM as outlined in WebGL Insights Chapter 16. import argparse import numpy import imageio import math # Handling arguments parser = argparse.ArgumentParser(descrip ...

Substitute the values in a data table with their ongoing consecutive sequence

I have been successfully replacing all the numbers in my dataframe with their current positive streak number. However, I find my code to be quite messy as I am doing it column by column and manually mentioning the column names each time. Can anyone suggest ...

Generating a figure with multiple subplots using Sympy

Currently working with sympy and matplotlib, I am aiming to create a plot with multiple subplots in a similar fashion to how it's done using pylab.subplot while utilizing numpy. In theory, this task should be straightforward, but as I delved into it, ...

Guide to subtracting elements within a list

I have created a function that takes in a list of numbers such as [0.5, -0.5, 1] and then outputs a new list with each index containing the sum of the differences between the current value and all other values. For example, if the input is [0.5, -0.5, 1], ...

I'm looking for a simple method to incorporate a legend into my subplots

Just joined this site and excited to share my Python code for plotting vectors, eigenvectors, and their dot product with a matrix. I want to add a legend with colors for each vector/eigenvector on the subplots. Check out the code below: import numpy as n ...

Splitting arrays at their edges

Query: Given an ndarray: In [2]: a Out[2]: array([0, 1, 2, 3, 4, 5, 6, 7, 8, 9]) I am searching for a method that would result in: array([7, 8, 9, 0, 1]) Example: Starting at index 8, crossing the array boundary and stopping at index 2 (included). When ...

Top method for creating an edge table from a datamatrix using Python

I have a table T with two columns - 'ID' and 'Genes', which contain lists of genes (Strings). My goal is to generate a graph where each gene is represented as a node, connected by edges to genes that share one different ID. The challenge is that my table r ...

Performing computations on large dense matrices using numpy

As I embark on training a neural network, I am faced with a significant challenge. I have a massive 212,243 × 2500 dense matrix labeled phi, along with vectors y (212243) and w (2500). These are stored as numpy arrays of double values. My goal is to calcu ...

The power trio: Python, Numpy, and OLS working together

Although the code provided is close to what I need, there is a minor adjustment required. I aim to replace c[1] with c[1:] in order to perform regression against all the x variables instead of just one. However, upon making this change and adding the neces ...

Adding up the elements of a numpy array

I am currently working on developing a polynomial calculator that allows me to input the largest coefficient. However, I am facing an issue with the xizes variable, which is producing multiple arrays representing the function image. As a result, the functi ...

What is the best way to add up values in a 3D numpy array based on a condition?

Having a 3-dimensional Numpy array containing only 0s and 1s as shown below: array([[[ 1, 1, 0, 1], [ 0, 0, 1, 1]], [[ 1, 1, 1, 1], [ 0, 1, 0, 1]]]) The objective is to perform an "addition" operation on each value within a "line" ...

Are there any more concise methods for generating a list consisting of the same float?

Can you abbreviate the following expression using shorthand: x = [0.5, 0.5, 0.5, 0.5, 0.5, 0.5, 0.5, 0.5, 0.5, 0.5, 0.5, 0.5] to something like this? x = ([0.5]*12)? ...

Separate the numpy array based on the value in the initial column

I'm dealing with a NumPy array that looks like this: [[ 0 935] [ 0 331] [ 0 322] [ 1 339] [ 1 773] [ 2 124] [ 2 340] [ 3 810] [ 5 936] [ 5 252]] and I want to split it into separate arrays as follows: [[ 0 935] [ 0 331] [ 0 322 ...

Troublesome behavior exhibited by Numpy's einsum. How to catch it?

When numpy einsum throws the error shown below, what is usually the underlying issue? Traceback (most recent call last): File "rmse_iter.py", line 30, in <module> rmse_out = np.sqrt(np.einsum('ij,ij->i',diffs,diffs)/3.0) TypeError: invalid ...

Contrasting pandas aggregators: Exploring the disparity between .first() and .last()

I'm interested in understanding the specific functionality of last() and first() when applied to resampling. My interpretation is that when numerical arguments are passed into these functions, like 3 for example, they return the first 3 months or years. I ...

Generate Numpy array without explicitly specifying elements

Using the following initial array: x = range(30,60,2)[::-1]; x = np.asarray(x); x array([58, 56, 54, 52, 50, 48, 46, 44, 42, 40, 38, 36, 34, 32, 30]) You need to create a new array similar to this: (Note that the first item repeats) However, if there is ...

What could be the reason for the difference in my IDFT computation compared to the value provided by np.fft.ifft

I have been working on validating a basic IDFT routine that I developed: ############################################################### #Custom IDFT Functions ############################################################### def simple_idft(data_f): dat ...

Extracting Nested Numpy Arrays

I am dealing with a pandas Series that contains one numpy array per entry, all of the same length. My goal is to convert this into a 2D numpy array. Despite knowing that Series and DataFrames don't handle containers well, when using np.histogram(.,.)[0] on ...

An efficient method for computing the matrix product A multiplied by its transpose in Python (without using numpy)

If you have a list called A that contains only 0's and 1's in the form of nested lists, what is the most pythonic (and efficient) method to calculate the product of A * A' without relying on numpy or scipy? One way to achieve this using num ...

The concept and notation of universal functions in numpy: understanding the basics

Currently, I am studying the numpy package and have come across this code snippet: import numpy as np a = np.array([[1,2,3], [4,5,6]]) np.add.reduce(a) My confusion lies in the dot notation: np.add.reduce(a) This seems different from the more straightf ...

What is the reason for comparing this array to two values instead of just one?

I'm really struggling to comprehend the meaning of this section of code. Can someone please explain why y.values is being compared to a tuple with two values, even though the array is just a single row (650,)? import pandas as pd import numpy as np i ...

Suboptimal utilization of multiprocessing for numpy computations

Looking to speed up some calculations using Python's multiprocessing module alongside numpy. Here’s a basic example: import time import numpy from multiprocessing import Pool def test_func(i): a = numpy.random.normal(size=1000000) b = numpy.r ...

Exploring the world of multi-level indexing using tuples

Working with a multi-dimensional np.array can be tricky. Knowing the shape of the first N dimensions and the last M dimensions is essential for proper indexing, as shown below: >>> n = (3,4,5) >>> m = (6,) >>> a = np.ones(n + m) ...

Exploring how tolerance stack affects the combination of three different resistor values

Looking to conduct a tolerance stack circuit analysis with Python instead of Excel. To start, I have the following resistor values structured as Minimum | Nominal | Maximum: R1 -> 5 | 10 | 15 R2 -> 5 | 10 | 15 Total_R = R1 + R2 Theoretically, this will ...

Inquiries about improving style and efficiency when incorporating a new calculated column derived from multiple rows into a pandas data frame

Seeking advice on improving style and efficiency of code, I am attempting to add a calculated data column to a pandas dataframe based on values from other columns in the same row. One method I tried involved using conditions that worked effectively with o ...

Manipulate DataFrame in Python using masks to generate a fresh DataFrame

I have a DataFrame that includes columns for date, price, MA1, MA2, and MA3. After filtering the data based on a specific condition, I get a subset of rows where MA1, MA2, and MA3 are equal. date price MA1 MA2 MA3 date1 price1 11 11 11 date4 pri ...

Tips for arranging the angles in a polar plot in a clockwise direction with the starting angle set at 0 degrees on top

I am currently using matplotlib and numpy to generate a polar plot within my project. Below is a snippet of the code I've been working with: import numpy as np import matplotlib.pyplot as plt angle = np.arange(0, 360, 10, dtype=float) * np.pi / 180.0 arb ...

Having trouble using the Python append method for axis=1 in a 2D array?

#Issue with Python's append function when axis=1 in 2D array. import numpy as np arr = np.array([[11, 15, 10, 6], [10, 14, 11, 5], [12, 17, 12, 8], [15, 18, 14, 9]]) print(arr) ...

What is the best method for incrementally transferring significant volumes of data to memory?

Currently, I am engaged in processing signals on an extensive dataset of images. This involves converting the images into large feature vectors that follow a specific structure (number_of_transforms, width, height, depth). Due to the size of these feature ...

Leveraging numpy arrays for handling both integer values and arrays as input

As a Matlab user transitioning into Python, I attempted to code a minimal version of the de2bi function in Python. This function converts a decimal number into binary with the right-most significant bit first. However, I encountered some confusion when wor ...