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Articles on Trending Technologies
Technical articles with clear explanations and examples
Data Manipulation in R with data.table
Data manipulation is a crucial step in the data analysis process, as it allows us to prepare and organize our data in a way that is suitable for the specific analysis or visualization. There are many different tools and techniques for data manipulation, depending on the type and structure of the data, as well as the specific goals of the manipulation. The data.table package is an R package that provides an enhanced version of the data.frame class in R. It’s syntax and features make it easier and faster to manipulate and work with large datasets. The date.table is one ...
Read MoreHow to convert more than one column in R data frame to from integer to numeric in a single line code?
To convert columns of an R data frame from integer to numeric we can use lapply() function. For example, if we have a data frame df that contains all integer columns then we can use the code lapply(df,as.numeric) to convert all of the columns data type into numeric data type.Example1Consider the below data frame −set.seed(871) x1
Read MoreHow to remove a character in an R data frame column?
To remove a character in an R data frame column, we can use gsub() function which will replace the character with blank. For example, if we have a data frame called df that contains a character column say x which has a character ID in each value then it can be removed by using the command gsub("ID", "", as.character(df$x)).Example1Consider the below data frame −> x1 x2 df1 df1Output x1 x2 1 Male1 8 2 Female1 4 3 Male1 9 4 Male1 2 5 Male1 7 6 Female1 5 7 Male1 3 8 ...
Read MoreHow to find the R version you are using?
Most of the times, we need to use packages in R and some packages are restricted to different versions in R, generally to newer versions. Therefore, we might need to find which version of R we are using. To find the R version, we can directly use the command R.Version().ExampleR.version.stringOutput[1] "R version 4.0.2 (2020−06−22)"
Read MoreHow to create date object in Java?
Using the Date classYou can create a Date object using the Date() constructor of java.util.Date constructor as shown in the following example. The object created using this constructor represents the current time.Exampleimport java.util.Date; public class CreateDate { public static void main(String args[]) { Date date = new Date(); System.out.print(date); } }OutputThu Nov 02 15:43:01 IST 2018Using the SimpleDateFormat classUsing the SimpleDateFormat class and the parse() method of this you can parse a date string in the required format and create a Date object representing the specified date.Exampleimport java.text.ParseException; import java.text.SimpleDateFormat; ...
Read Morestring.sub() function in Lua
Another important function of the Lua’s string library is the string.sub() function. The string.sub() function is used to extract a piece of the string.The string.sub() function takes three arguments in general, the first argument being the name of the string from which we want to extract a piece, the second argument is the i-th index or say, the starting index of the string piece that we want, and the third and the last argument is the j-th index of the last index of the string piece we want.It should be noted that both the starting index and the ending index, ...
Read MoreSmallest possible length constituting greatest frequency in JavaScript
ProblemWe are required to write a JavaScript function that takes in an array of numbers, arr, as the first and the only argument.Our function is supposed to find the smallest possible length of a (contiguous) subarray of the array arr, that has the same greatest frequency of any element as the whole array.For example, if the input to the function isInputconst arr = [55, 77, 77, 88, 55];Outputconst output = 2;Output ExplanationThe input array has the greatest frequency for any element of 2 because both elements 55 and 77 appear twice.Of the subarrays that have the greatest frequency as the ...
Read MoreHow to get a value from the cell of a Pandas DataFrame?
To get a value from the cell of a DataFrame, we can use the index and col variables.StepsCreate a two-dimensional, size-mutable, potentially heterogeneous tabular data, df.Print the input DataFrame, df.Initialize the index variable.Initialize the col variable.Get the cell value corresponding to index and col variable.Print the cell value.Exampleimport pandas as pd df = pd.DataFrame( { "x": [5, 2, 1, 9], "y": [4, 1, 5, 10], "z": [4, 1, 5, 0] } ) print("Input DataFrame is:", df) index = 2 col = "y" cell_val = df.iloc[index][col] print "Cell ...
Read MoreHow to select all columns except one in a Pandas DataFrame?
To select all columns except one column in Pandas DataFrame, we can use df.loc[:, df.columns != ].StepsCreate a two-dimensional, size-mutable, potentially heterogeneous tabular data, df.Print the input DataFrame, df.Initialize a variable col with column name that you want to exclude.Use df.loc[:, df.columns != col] to create another DataFrame excluding a particular column.Print the DataFrame without col column.Exampleimport pandas as pd df = pd.DataFrame( { "x": [5, 2, 1, 9], "y": [4, 1, 5, 10], "z": [4, 1, 5, 0] } ) print("Input DataFrame is:", df) col = ...
Read MoreHow to calculate transpose of a matrix using C program?
Transpose of a matrixThe transpose of a matrix is the one whose rows are columns of the original matrix, i.e. if A and B are two matrices such that the rows of the matrix B are the columns of the matrix A then Matrix B is said to be the transpose of Matrix A.The logic used to change m(i, j) matrix to m(j, i) is as follows −for (i = 0;i < m;i++) for (j = 0; j < n; j++) transpose[j][i] = matrix[i][j];Program 1In this example, we shall print the transpose of a matrix using for ...
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