To find the number of non-missing values in each group of an R data frame, we can convert the data frame to data.table object and then use the sum function with negation of is.na.For Example, if we have a data frame called df that contains a grouping column say Group and a numerical column with few NAs say Num then we can find the number of non-missing values in each Group by using the below given command −setDT(df)[,sum(!is.na(df)),by=.(Group)]Example 1Following snippet creates a sample data frame −Grp

To create stacked bar chart with percentages on Y-axis using ggplot2 in R, we can use fill argument inside geom_bar and put the second categorical variable with position set to fill.For Example, if we have a data frame called with two categorical columns say C1 and C2 then we can create stacked bar chart with percentages on Y-axis using the below mentioned command −ggplot(df,aes(C1))+geom_bar(aes(fill=C2),position="fill")ExampleFollowing snippet creates a sample data frame −f1

To find the column variance if some columns are categorical in R data frame, we can follow the below steps −First of all, create a data frame.Then, use numcolwise function from plyr package to find the column variance if some columns are categorical.ExampleCreate the data frameLet’s create a data frame as shown below −Group

To find the sum of rows of a column based on multiple columns in R data frame, we can follow the below steps −First of all, create a data frame.Then, use aggregate function to find the sum of rows of a column based on multiple columns.ExampleCreate the data frameLet’s create a data frame as shown below −Grp1

To subset groups that occur less than n times in R data frame, we can use filter function of dplyr package.For Example, if we have a data frame called df that contains a grouping column say Group then we can subset groups that occur less than 4 times by using the below mentioned command −df%%group_by(Group)%%filter(n()=4)Example 1Following snippet creates a sample data frame −Grp

To create bar plot of one column in an R data frame using ggplot2, we can use rownames of the data frame as x variable in aes.For Example, if we have a data frame called df that contains two columns say X and Y and we want to create the bar plot of values in Y then we can use the below mentioned command −ggplot(df,aes(rownames(df),Y))+geom_bar(stat="identity")ExampleFollowing snippet creates a sample data frame −x1

To display infinity and minus infinity symbol in one base R plot, we can use text function and expression function. Inside expression function we can put infinity word for the display of infinity and infinity word with minus sign for the display of minus infinity.Check out the below Examples to understand how it can be done.Example 1To display infinity and minus infinity symbol in one base R plot use the following code −plot(1:10, type="n") text(c(1, 5), expression(-infinity, infinity))OutputIf you execute the above given snippet, it generates the following Output −Example 2To display infinity and minus infinity symbol in one base ... Read More

To display infinity symbol in base R plot, we can use text function and expression function. Inside expression function we can put infinity word for the display of infinity. For Example, if we want to display infinity at position X=2 and Y=4 then we can use the below mentioned command −text(2, 4, expression(infinity))Example 1To display infinity symbol in base R plot, use the snippet given below −plot(1:10, type="n") text(5, 5, expression(infinity))OutputIf you execute the above given snippet, it generates the following Output −Example 2To display infinity symbol in base R plot, use the snippet given below −plot(1:10, type="n") text(5, 5, ... Read More

To subtract all values in a vector from all values in another vector in R, we can use sapply function with subtraction sign.For Example, if we have two vectors say X and Y and we want to subtract all values in Y from all values in X then we can use the command given below −sapply(X,"-",Y)Example 1Following snippet creates a sample data frame −x1

To find the sum of corresponding elements in all matrix’s stored in a list in R, we can use Reduce function with plus sign. For Example, if we have a list called LIST that contains multiple matrices and we want to find the sum of corresponding elements then we can use the command given below −Reduce("+",LIST)Check out the below Examples to understand how it works.Example 1To find the sum of corresponding elements in all matrix’s stored in a list in R, use the following snippet −List