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Articles on Trending Technologies
Technical articles with clear explanations and examples
Find the number of non-missing values in each column by group in an R data frame.
To find the number of non-missing values in each column by group in an R data frame, we can use summarise_each function of dplyr package with negation of is.na function.For Example, if we have a data frame called df that contains a grouping column say G and some other columns having few NAs then we can find the number of non-missing values in each column by grouping column G with the help of below command −df%%group_by(G)%%summarise_each(funs(sum(!is.na(.))))Example 1Following snippet creates a sample data frame −Group
Read MoreHow to display x-bar in base R plot?
To display x-bar in base R plot, we can use text function and define the bar with bar function inside expression function.For example, if we have a vector called x that contains first ten numbers (1 to 10) then we can display it’s mean inside the base R plot by using the command given below −text(0.97, 5.5, expression(bar("x")))Check out the examples given below to understand how it works.Example 1Use the code given below to display x-bar in base R plot −plot(mean(1:100)) text(0.97, 50.5, expression(bar("x")))OutputIf you execute the above given snippet, it generates the following Output −Example 2Use the code given ...
Read MoreHow to color scatterplot points based on a threshold using ggplot2 in R?
To color scatterplot points based on a threshold using ggplot2, we first need to define a column with the threshold value and then we can use that column inside aes for coloring. The column with threshold can be created by using cut function.Check out the example given below to understand how it can be done.ExampleFollowing snippet creates a sample data frame −x
Read MoreHow to create multiple regression lines using ggplot2 in R?
To create multiple regression lines using ggplot2, we can use grouping inside aes.For example, if we have a data frame called that contains two numerical columns say x and y and a categorical column say C then the regression lines between x and y for all the categories in C can be created by using the below given command −ggplot(df, aes(x, y, group=C))+geom_point()+stat_smooth(method="lm")ExampleFollowing snippet creates a sample data frame −data(mtcars) head(mtcars, 20)OutputThe following dataframe is created − mpg cyl disp hp drat wt qsec vs am gear carb Mazda ...
Read MoreRecursively print all sentences that can be formed from list of word lists in C++
Given a list of words. The goal is to create all possible sentences that can be formed by taking words from the list using a recursive approach. You can only take one word at a time from both the lists.Let us see various input output scenarios for thisInput −sentence[row][col] = {{"I", "You"}, {"Do", "do not like"}, {"walking", "eating"}}Output −I Do walking I Do eating I like walking I like eating You Do walking You Do eating You like walking You like eatingExplanation − Taking one word from each list in sentence[0-2] gives above sentences.Input −sentence[row][col] = {{"work", "live"}, {"easy", "happily"}}Output −work ...
Read MoreHow to remove duplicate columns from a matrix in R?
To remove duplicate columns from a matrix in R, we can use unique function.For Example, if we have a matrix called M that contains some duplicate columns then we can use the below command to remove those duplicate columns −unique(M,MARGIN=2)Example 1Following snippet creates a sample matrix −M1
Read MoreHow to display text in base R plot with outline?
The display of text in base R plot with outline is not possible, for this purpose we would need to use shadowtext function of TeachingDemos package. The shadowtext function will be applied after creating the plot in base R.We will have to provide the location of the text inside the plot and some other arguments such as text that needs to be displayed, color of outline, and size for better display.Example 1Use the following code to display text in base R plot with outline −plot(1) shadowtext(1.2, 1.2, "Point at 1", col="white", cex=2)OutputIf you execute the above given code, it generates ...
Read MoreDifferentiate between categorical and numerical independent variables in R.
For categorical variable, each level is considered as an independent variable and is recognized by factor function. On the other hand, the numerical independent variable is either continuous or discrete in nature.Check out the Example given below for linear regression model summary to understand the difference between categorical and numerical independent variables.ExampleFollowing snippet creates a sample data frame −x
Read MoreReverse and Add Function in Java
We are given with an integer and the agenda here is to reverse the digits of the number and add the reversed number to the original number and check if the resultant number is a palindrome or not and the process is repeated until it does. The breaking point of the process is 1000 iterations and a value greater than the maximum long value( Long.MAX_VALUE).For ExamplesInput − 1678Output − Palindrome of the given input 1678 293392Explanation − The input number is first reversed and then added to the original number, it is then checked for palindrome if it is not a palindrome ...
Read MoreHow to create an upper triangular matrix using vector elements in R?
To create an upper triangular matrix using vector elements, we can first create the matrix with appropriate number of columns and rows then take the transpose of that matrix. After that we will assign the lower triangular matrix elements to 0.The selection of number of rows and columns plays an important role here so we need to be careful while choosing them.Check out the examples given below to understand how it can be done.Example 1Following snippet creates a vector −x1
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