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Articles by Nizamuddin Siddiqui
Page 126 of 196
Find the number of non-missing values in each group of an R data frame.
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
Read MoreCreate stacked bar chart with percentages on Y-axis using ggplot2 in R.
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
Read MoreSubset groups that occur greater than equal to n times in R dataframe.
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
Read MoreHow to find the sum of rows of a column based on multiple columns in R data frame?
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
Read MoreHow to display infinity symbol in base R plot?
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 MoreR programming to subtract all values in a vector from all values in another vector.
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
Read MoreR programming to find the sum of corresponding elements in all matrix’s stored in a list.
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
Read MoreHow to find the sum of all array elements in R?
To find the sum of all array elements in R, we can use Reduce function with plus sign. For Example, if we have an array called ARRAY and we want to find the sum of all values in this array then we can use the command Reduce("+",ARRAY).Check out the below Examples to understand how it works.Example 1To find the sum of all array elements in R use the snippet given below −Array1
Read MoreExtract a data frame column values as a vector by matching a vector in R.
To extract a data frame column values as a vector by matching a vector in R, we can use subsetting with %in% operator.For Example, if we have a data frame called df having a column say C and a vector V and we want to extract values in C if they match with V then we can use the command given below −df[df$C %in% V,"C"]Example 1Following snippet creates a sample data frame and vector −x1
Read MoreHow to change the name of single column using setNames in R?
To change the name of single column using setNames, we would need to specify the column name that needs to be changed.For example, if we have a data frame called df that contains three columns say Var1, var2, and Var3 and we want to change var2 to Var2 then we can use the command as follows −setNames(df,replace(names(df),names(df)=="var2","Var2"))Example 1Following snippet creates a sample data frame −x
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