Programming Articles - Page 1300 of 3366

In this program, we will draw an ellipse on an image in using the OpenCV library. We will use the OpenCV function ellipse() for the same.Original ImageAlgorithmStep 1: Import cv2. Step 2: Read the image using imread(). Step 3: Set the center coordinates. Step 4: Set the axes length. Step 5: Set the angle. Step 6: Set start and end angle. Step 6: Set the color. Step 7: Set the thickness. Step 8: Draw the ellipse by passing the above parameters in the cv2.ellipse function along with the original image. Step 9: Display the final output.Example Codeimport cv2 image = ... Read More

In this program, we will draw a simple line on an image using the OpenCV function line().Original ImageAlgorithmStep 1: Import cv2. Step 2: Read the image using imread(). Step 3: Get the dimensions of the image using the image.shape method. Step 4: Define starting point of the line. Step 5: Define the end point of the line. Step 6: Define the thickness of the line. Step 7: Draw the line using the cv2.line() function and pass Step 3 to Step 4 as parameters.Example Codeimport cv2 image = cv2.imread('testimage.jpg') height, width, channels = image.shape startpoint = (0, 0) endpoint = ... Read More

In this program, we will change the color scheme of an image from rgb to grayscaleAlgorithmStep 1: Import OpenCV. Step 2: Read the original image using imread(). Step 3: Convert to grayscale using cv2.cvtcolor() function.Example Codeimport cv2 image = cv2.imread('colourful.jpg') cv2.imshow('Original',image) grayscale = cv2.cvtColor(image, cv2.COLOR_BGR2GRAY) cv2.imshow('Grayscale', grayscale)OutputOriginal Image:Grayscale Image:

To find the sum of every n values in R data frame columns if there exist missing values, we can use rowsum function along with rep function that will repeat the sum for rows and na.rm=TRUE to exclude the rows with missing values. For example, if we have a data frame called df that contains 4 columns each containing twenty values with some missing values then we can find the row sums for every 5 rows by using the command rowsum(df,rep(1:5,each=4),na.rm=TRUE).Example Live Demox1

In this article, we can take a program code to show how we can make a 3D plot interactive using Jupyter Notebook.StepsCreate a new figure, or activate an existing figure.Create fig and ax variables using subplots method, where default nrows and ncols are 1, projection=’3d”.Get x, y and z using np.cos and np.sin function.Plot the 3D wireframe, using x, y, z and color="red".Set a title to the current axis.To show the figure, use plt.show() method.Exampleimport matplotlib.pyplot as plt import numpy as np fig = plt.figure() ax = fig.add_subplot(111, projection='3d') u, v = np.mgrid[0:2 * np.pi:30j, 0:np.pi:20j] x = np.cos(u) * ... Read More

Using Pandas, we will create a dataframe and set the vertical lines on the created axes, using axvline lines.StepsUsing panda we can create a data frame.Creating a data frame would help to create help.Using axvline(), add a vertical line across the axes, where color is green, linestyle="dashed".Using axvline(), add a vertical line across the axes, where color is red, linestyle="dashed".Using plt.show(), show the plot.Exampleimport pandas as pd from matplotlib import pyplot as plt df = pd.DataFrame(index=pd.date_range("2019-07-01", "2019-07-31")) df["y"] = 1 ax = df.plot() ax.axvline("2019-07-24", color="green", linestyle="dashed") ax.axvline("2019-07-31", color="red", linestyle="dashed") plt.show()OutputRead More

We can use the attribute sharex = "ax1", and then, use the subplot method to zoom the subplots together.StepsAdd a subplot to the current figure with (nrow = 1, ncols = 2, index = 1).Add line on the current subplot with (nrow = 1, ncols = 2, index = 1).Add a subplot to the current figure with (nrow = 1, ncols = 2, index = 2).Add line on the current subplot with (nrow = 1, ncols = 2, index = 2), where sharex can help to share the x or y `~matplotlib.axis` with sharex and/or sharey. The axis will have ... Read More

To check if an R matrix column contains only duplicate values, we can use dim function for the dimension of the column after accessing the matrix column with table function. For example, if we have a matrix called M having five columns then we can check whether first column contains only duplicate values using the command dim(table(M[,1]))==1ExampleConsider the below data frame − Live DemoM1

In this program, we will write an image or save an image to a file using OpenCV.AlgorithmStep 1: Import cv2 Step 2: Read the image using opencv.imread() Step 3: Save the image using opencv.imwrite(filename, image)Example Codeimport cv2 import os image = cv2.imread('testimage.jpg') directory = r'C:\Users\prasa\Desktop' os.chdir(directory) cv2.imwrite('CAMERAMAN.jpg', image)OutputThis program will save the image in the directory as same as the original image directoryExplanationEnsure that you have set the proper directory in order for the program to execute without errors.

In this article, we will learn how to read and display images using the OpenCV library.OpenCV is a library of programming functions mainly aimed at real time computer vision. Before reading an image, make sure that the image is in the same directory as your program.AlgorithmStep 1: Import OpenCV. Step 2: Read an image using imread(). Step 3: Display the image using imshow().Example Codeimport cv2 as cv image = cv.imread ('ronaldo.jpg') cv.imshow('Cristiano Ronaldo', image)Output