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Articles by Nizamuddin Siddiqui
Page 130 of 196
How to add two columns if both contains missing values in R?
If we want to add two columns of an R data frame and each of them contains missing values then the addition of columns can be done in one of the following ways −Adding both the column values if they are numeric.Returning numeric if one of the columns has missing value.Returning NA if both the columns have missing value.To this we can take help of apply function and ifelse function as shown in the below given examples.Example 1Following snippet creates a sample data frame −x1
Read MoreHow to take transpose of vectors stored in an R list?
We can take the transpose of vectors stored in an R list by using Map function with do.call. For example, if we have a list called LIST that contains say ten vectors then we can transpose these vectors by using the command given below − do.call(Map,c(f=c,LIST))Check out the below examples to understand how it works.Example 1To take transpose of vectors stored in an R list, use the command given below −List1
Read MoreHow to subset a matrix based on values in a particular column in R?
To subset a matrix based on values in a particular column, we can use single square brackets and provide the row and column values. The column values will be set for the columns that we want to subset and the row value will be set for the values of the column using which we want to subset the matrix.Check out the below example to understand how it works.ExampleFollowing snippet creates a matrix −M
Read MoreHow to highlight outliers in a boxplot in R?
To highlight outliers in a boxplot, we can create the boxplot with the help of Boxplot function of car package by defining the id.method.For example, if we have a vector called V then the boxplot of V with highlighted outliers can be created by using the below given command −Boxplot(~V,id.method="y")Example 1To highlight outliers in a boxplot, use the command given below −library(car) x
Read MoreHow to check if a string contains only one type of character in R?
If a string contains more than one character then all of them could be same or different. If we want to check if a string contains only one type of character, then stri_count_fixed function of stringi package will be used with nchar function.Check out the below given examples to understand how it can be done.Example 1Following snippet creates a sample data frame −Countries
Read MoreHow to split a vector into smaller vectors of consecutive values in R?
To split a vector into smaller vectors of consecutive values, we can use split function with cumsum function.For example, if we have a vector called X that contains some consecutive values then we split X into smaller vectors of consecutive values by using the command given below −split(x,cumsum(c(1,diff(x)!=1)))Example 1Following snippet creates a vector −x1
Read MoreHow to find the mean based on single group value in an R data frame?
To find the mean based on single group value in an R data frame, we can use mean function with subsetting through single square brackets.For example, if we have a data frame called df that contains a categorical column say C having three groups Low, Medium, High and a numerical column say Num then mean of Num for Medium group can be found by using the command given below −mean(df$C[df$Num=="Medium"])Example 1Following snippet creates a sample data frame −Group
Read MoreHow to fill a data.table row with missing values in R?
Instead of filling missing values, we sometimes need to replace the data with missing values. This might be required in situations when missing values are coded with a number or the actual values are not useful or sensible for the data study. Also, we might want to replace the values with something else in the future.Check out the below given examples to understand how we can fill data.table row with missing values.Example 1Following snippet creates a data.table object −library(data.table) x1
Read MoreHow to subset matrix row values based on different columns?
Suppose we have a matrix called M that contains three columns and we want to subset row values of M but from different columns that means the subset will not have values only from a single column.Hence, before creating the subset we first need to find the column numbers that can be used for the creation of subset and this can be done with the help of sample function if column numbers are not known. After that we can use cbind function with single square brackets for subsetting.Check out the Examples given below to understand how it can be done.Example ...
Read MoreHow to find the row products for each row in an R matrix?
To find the row products for each row in an R matrix, we can use rowProds function of matrixStats package.For Example, if we have a matrix called MATRIX then we can find the row products for each row in MATRIX by using the command given below −rowProds(MATRIX)Example 1Following snippet creates a sample matrix −M1
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