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Articles by Nizamuddin Siddiqui
Page 109 of 196
How to extract unique rows by categorical column of a data.table object in R?
If we have categorical data in a data.table object and some values are duplicate then we might want to extract unique rows from that object.To extract unique rows by categorical column of a data.table object, we can use unique function and define the columns with by argument as shown in the below examples. To understand how the extraction is done check out the below examples.Example 1Following snippet creates a data.table object −library(data.table) grp
Read MoreHow to extract diagonal elements of a matrix in R without using diag function?
The diagonal elements of a matrix occur at the position where column and row indices are same hence, we can make use of those indices to extract diagonal elements of a matrix if we do not want to use diag function.For example, if we have a matrix called M then diagonal elements of M can be extracted by using the command given below − M[row(M)==col(M)]Check out the below examples to understand how it works.Example 1Following snippet creates a matrix −M1
Read MoreHow to create a data frame column with equally spaced values between 0 and 1 in R?
To create a data frame column with equally spaced values between 0 and 1, we can use ppoints function. For example, if we want to create a data frame df with hundred equally spaced values between 0 and 1 then we can use the below mentioned command −df
Read MoreHow to save the str output as a string in R?
To save the str output as a string in R, we can use capture.output function along with str function.For example, if we have a data frame called df and we want to store the str output of df as a string then we can use the command given below −capture.output(str(df))It would be better if we save it in an object as str_df
Read MoreHow to find the moving standard deviation in an R data frame?
To find the moving standard deviation in an R data frame, we can make use of rollapply function of zoo package.For example, if we have a data frame called df and we want to find the 2 moving standard deviations then we can use the below given command −rollapply(df,width=2,FUN=sd,fill=0,align="r")Example 1Following snippet creates a sample data frame −x1
Read MoreHow to change the background color of base R plot region?
To change the background color of base R plot region, we can follow the below steps −First of all, create a plot in base R to understand the difference.Then, use par function with bg argument where you can put color name and then create the same plot.ExampleCreate the plotLet’s create a barplot in base R as shown below −x
Read MoreHow to remove rows in R data frame that contains a specific number?
To remove rows in R data frame that contains a specific number, we can follow the below steps −First of all, create a data frame.Then, use single square subsetting with apply function to remove rows that contains a specific number.ExampleCreate the data frameLet’s create a data frame as shown below −x
Read MoreHow to display legend in base R with different colors?
To display legend in base R with different colors, we can follow the below steps −First of all, create a plot using plot function.Then, use legend function legend argument and col argument to display legend with different colors.ExampleCreate the plotLet’s create a plot of a vector x using plot function −x
Read MoreHow to find the mean of a column summarized by other column names and common values in those columns in R data frame?
To find the mean of a column summarized by other column names and common values in those columns in R data frame, we can follow the below steps −First of all, create a data frame.Then, melt the data frame using melt function from reshape2 package.After that, use dcast function to find the mean of a column summarized by other column names and common values in those columns.ExampleCreate the data frameLet’s create a data frame as shown below −S.No
Read MoreHow to decompose a time series with trend and seasonal components using loess method in R?
To decompose a time series with trend and seasonal components using loess method in R, we can follow the below steps −First of all, create a time series object.Then, use stl function to decompose the time series with trend and seasonal components.ExampleCreate the time series objectLet’s create a time series object using ts function −x
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