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R Programming Articles
Page 42 of 174
How to check whether a column exists in an R data frame?
If we have very large data set then it is highly that we forget the column names, therefore, we might want to check whether a particular column exists in the data frame or not if we know the column name. For this purpose, we can use grep function that will result the column name if exists in the data frame otherwise 0. To understand how it works check out the below examples.Example1ID
Read MoreHow to find the sum of squared deviations for an R data frame column?
The sum of squared deviations is the total of the square of difference between each value and the mean. To find this value, we need to create the formula in R platform. For example, if we have a data frame called df that contains a column x then the sum of squared deviations for x can be calculated by using sum((df$x−mean(df$x))^2).Example1y1
Read MoreHow to find the correlation of one variable with all the other variables in R?
To find the correlation of each variable with remaining variables, we can create a correlation matrix but for the correlation of only one variable with all the other variables we need to define the columns inside the cor function. The output will represent the columns and rows as passed inside the function.Example1y1
Read MoreHow to create a column with largest size string value in rows in an R data frame?
To create a column with largest size string value in rows, we can use apply function and define the size of the string for the largest value by creating a function as shown in the below examples. If the number of characters in all the columns are same or there exists some ties then the output will be the first one.Example1y1
Read MoreHow to create a frequency table in R that includes zero frequency for value that are not available?
When we use table function in R, the output shows the frequency of values that are available in the vector or in column of the data frame. If we want to create the table with the frequency zero for values that are not part of the vector or the column then first we need to convert them to factor first and then use the table function.Example1x1
Read MoreHow to find the sum of rows, columns, and total in a matrix in R?
To find the sum of row, columns, and total in a matrix can be simply done by using the functions rowSums, colSums, and sum respectively. The row sums, column sums, and total are mostly used comparative analysis tools such as analysis of variance, chi−square testing etc.Example1M1
Read MoreHow to use column index instead of column name while using group_by of dplyr in R?
When we use group_by function of dplyr package, we need to pass the column name(s) that are categorical in nature. If we want to use the index of the same column(s) then group_by_at function needs to be used, where we can pass the column index as the argument.Example1y1
Read MoreHow to check if a list element is greater than a certain value in R?
If we have a list that contains numeric elements and we want to check whether the elements are greater than a certain value then as.numeric function can be used. The output of the function will be in 0/1 format where 0 represents FALSE and 1 represents TRUE. For example, if we have a list called LIST then to check whether elements in LIST are greater than 2 can be done as as.numeric(LIST>2).Example1List15)Output[1] 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1 1 0 0Example2List22)Output[1] 1 1 1 1 0 0 1 0 1 1 1 1 1 0 0 0 1 1 1 0
Read MoreHow to find unique matrices in a list in R?
A list can contain many types of elements such as vectors, matrices, data frames etc. If we have matrices in a list then to find unique matrices in that list, we can simply use unique function. For example, if we have a list called LIST that contains matrices having some duplicate matrices then unique matrices can be extracted by using unique(LIST).Example1list(M1=matrix(1:25, ncol=5), M2=matrix(1:25, ncol=5), M3=matrix(1:25, ncol=5), M4=matrix(rpois(25, 5), ncol=5)) List1Output$M1 [, 1] [, 2] [, 3] [, 4] [, 5] [1, ] 1 6 11 16 21 [2, ] 2 7 12 17 22 [3, ] 3 8 13 18 ...
Read MoreHow to find mean and standard deviation from frequency table in R?
To find the mean and standard deviation from frequency table, we would need to apply the formula for mean and standard deviation for frequency data. For example, if we have a data frame called df that contains a column x for units and frequency for counts then the mean and standard deviation can be calculated as −Mean = sum(df$x*df$frequency)/sum(df$frequency) SD = sqrt(sum((df$x−Mean)**2*df$frequency)/(sum(df$frequency)−1)) respectively.Example1x
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