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To extract only first element from a list, we can use sapply function and access the first element with double square brackets. For example, if we have a list called LIST that contains 5 elements each containing 20 elements then the first sub-element can be extracted by using the command sapply(LIST,"[[",1).Example1Consider the below data frame − Live DemoList1
To find the monthly average from different date data, we first need to extract the months and year from date column and then find the average using aggregate function. For example, if we have a data frame called df which has three columns say x, month, and year then the monthly average can be found by using the command −aggregate(x~Month+Year,df,mean)Example1Consider the below data frame − Live DemoDate1
To change the code “Yes” to 1, we can use ifelse function and set the Yes to 1 and others to 0. For example, if we have a data frame called df that contains a character column x which has Yes and No values then we can convert those values to 1 and 0 using the command ifelse(df$x=="Yes",1,0).Example1Consider the below data frame − Live DemoAgree
To find the count of a particular character in a string vector we can use nchar function along with gsub. For example, if we have a vector called x that contains string such India, Russia, Indonesia then we can find the number of times character i occurred then we can use the command nchar(gsub("[^i]","",x)) and the output will be 1 1 1 because first I’s in India and Indonesia will not be considered as they are in uppercase.Example1 Live Demox1
To find the mean squared error for linear model, we can use predicted values of the model and find the error from dependent variable then take its square and the mean of the whole output. For example, if we have a linear model called M for a data frame df then we can find the mean squared error using the command mean((df$y-predict(M))^2).Example1Consider the below data frame − Live Demox1
To create a data frame column with letters of both sizes, we can simply use the letters function and LETTERS function, the first one corresponds to lowercase letters and the latter corresponds to uppercase letters with single square brackets as shown in the below examples.Example1 Live Demodf1
To convert a matrix to binary matrix, we can use as.matrix function and converting the matrix to logical matrix then adding 0 to the values greater than 0. For example, if we have a matrix called M then it can be converted to a binary matrix using the command −as.matrix((M
To find the index of the nearest smallest number in an R data frame column, we can use which function along with subsetting for the value for which we want to find the index of the nearest smallest number. To understand how it can be done check out the below examples.Example1Consider the below data frame − Live DemoID
To create a date vector with randomization, we can use sample function but the dates need to be read with as.Date function. For example, if we have 2 dates say 2021-01-01 and 2021-02-02 then a vector with randomization of these three dates can be created by using the command −sample(c(as.Date("2021-01-01"),as.Date("2021-02-02")),100,replace=TRUE)Example1 Live DemoDate1
To multiply large numbers with all digits in the output, we can use mul.bigz function of gmp package. For example, if we have two vectors say x and y each containing numbers of large size then the multiplication of these numbers that will return all the digits of the multiplication can be done by using the command mul.bigz(x,y).Example1Loading gmp package and multiplying vectors containing large number values −library(gmp) x1