So, let’s start exploring matrix functions in R.<\/p>\n
What is R Matrix and Matrix Function in R?<\/h2>\n
First of all, let’s revise what\u00a0are matrices. A matrix is a two-dimensional rectangular data set. Thus it can be created using vector input into the matrix function. Also, a matrix is a collection of numbers arranged into a fixed number of rows and <\/em>columns<\/em>.<\/strong> The numbers present in the matrix are real numbers. We then carry out the memory replication of the matrix using\u00a0 the matrix function. Hence, the data elements must be of the same basic type. Matrices functions are those functions which we use in matrices.<\/p>\n There are two types of matrix function in R:<\/p>\n In the above paragraph, we have discussed about the R matrix. Now let’s proceed to detail understanding of the types of matrix function in R.<\/p>\n You must learn about Vector Operations in R<\/a><\/strong><\/em><\/p>\n Let’s now understand the R apply() function and its usage with examples.<\/p>\n It applies functions over array margins. It returns a vector or array or list of values obtained by applying a function to margins of an array or matrix.<\/p>\n Arguments – <\/strong>The arguments for the apply function in R are explained below:<\/p>\n For example –<\/strong>\u00a0A matrix 1 indicates rows, matrix 2 indicates columns, matrix c(1, 2) indicates rows and columns. In this, X is named\u00a0dimnames and it can be a character vector selecting dimension names.<\/p>\n Apply functions are a family of functions in base R, which allow us to perform actions on many chunks of data. An apply function is a loop, but it runs faster than loops and often with less code. And, there are different\u00a0apply() functions.<\/p>\n The called function could be:<\/p>\n We can perform operations with very few lines of code in apply().<\/p>\n Have you checked – R Array Function<\/a><\/strong><\/em><\/p>\n So, let us start with apply(), which operates on arrays:<\/p>\n my.matrx is a matrix with 1-5 in column 1, 6-10 in column 2, and 11-15 in column 3<\/em>. my.matrx is used to show some of the basic uses of the apply function.<\/p>\n Output:<\/strong><\/p>\n Example 1: Using apply to find row sums<\/strong><\/p>\n We will summarize the data in matrix m by finding the sum of each row. The arguments are; X = m, MARGIN = 1 (for\u00a0row), and FUN = sum.<\/p>\n It will return a vector containing the sums for each row.<\/p>\n Example 2: Creating a function in the arguments<\/strong><\/p>\n Now, we will find how many data points (n) are in each column of m by using columns, MARGIN = 2. Thus, we can use the length function to do this.<\/p>\n There isn\u2019t a function in R<\/a> to find n-1 for each column. So, if we want to create our own function and if the function is simple, you can create it right inside the arguments for applying. In the arguments, we created a function that returns length – 1.<\/p>\n As we have seen, the function returned a vector of n-1 for each column.<\/p>\n Example 3: Transforming data<\/strong><\/p>\n In the previous examples, we used apply\u00a0to summarize over a row or column. We can also use apply to repeat a function on cells within a matrix. Now, in this example, we will learn how to use apply function to transform the values in each cell. Please give more attention to the MARGIN argument.<\/p>\n Code Display:<\/strong><\/p>\n Output:<\/strong><\/p>\n Example 4: Vectors<\/strong><\/p>\n In previous examples, we have learned several ways to use the apply function on a matrix. But what if we want to loop it through a vector instead? Will the apply function work? Let’s check.<\/p>\n Output:<\/strong><\/p>\n When we will run this function, it will return the error: Error in apply(v, 1, sum): dim(X) must have a positive length. As we can see, this didn\u2019t work because apply was expecting the data to have at least two dimensions. If we are using data in a vector, we need to use\u00a0lapply,\u00a0sapply, or\u00a0vapply\u00a0instead.<\/p>\n Any doubts in R Matrix Function till now? Please comment below.<\/p>\n It is a dimension preserving variant of “sapply” and “lapply”.<\/p>\n sapply\u00a0is a\u00a0user-friendly\u00a0version and is a wrapper of\u00a0lapply. By default, sapply\u00a0returns a vector, matrix or an array.<\/p>\n Arguments –<\/strong> The arguments used in the sapply() function are discussed below:<\/p>\n Do you know about R Lists<\/a><\/strong><\/em><\/p>\n sapply() function applies a function to margins of an array or matrix.<\/p>\n Usage –\u00a0<\/strong>sapply(x,\u00a0func, …, simplify = TRUE, USE.NAMES = TRUE)<\/p>\n sapply function in R Example:<\/strong><\/p>\n Output:<\/strong><\/p>\n Sum up for each row:<\/p>\n Multiply all values by 10:<\/p>\n Used for array, margin set to 1:<\/p>\n Two-dimension array, the margin can be 1 or 2:<\/p>\n\n
What is apply() function in R?<\/h3>\n
1. apply() function in R<\/h4>\n
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2. The apply() family<\/h4>\n
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3. How to use apply() function in R?<\/h4>\n
3.1 apply function in R examples<\/h5>\n
my.matrx <- matrix(c(1:5, 6:10, 11:15),\u00a0nrow\u00a0= 5,\u00a0ncol\u00a0= 3)\r\nmy.matrx<\/pre>\n
![\"matrx](\"https:\/\/data-flair.training\/blogs\/wp-content\/uploads\/sites\/2\/2017\/09\/matrx-function-output.jpg\")
<\/a><\/p>\napply(my.matrx, 1, sum)<\/pre>\n
apply(my.matrx, 2, length)<\/pre>\n
apply(my.matrx, 2, function (x) length(x)-1)<\/pre>\n
my.matrx2 <- apply(my.matrx,1:2, function(x) x+3).\r\nmy.matrx2<\/pre>\n
![\"apply](\"https:\/\/data-flair.training\/blogs\/wp-content\/uploads\/sites\/2\/2017\/09\/apply-my-matrx-input.jpg\")
<\/a><\/p>\n![\"apply](\"https:\/\/data-flair.training\/blogs\/wp-content\/uploads\/sites\/2\/2017\/09\/apply-my-matrx-output.jpg\")
<\/a><\/p>\nvec\u00a0<- c(1:5)\r\nvec<\/pre>\n
![\"Example](\"https:\/\/data-flair.training\/blogs\/wp-content\/uploads\/sites\/2\/2017\/09\/Example-of-Vectors.jpg\")
<\/a><\/p>\nWhat is sapply() function in R?<\/h3>\n
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\nLapply(X, FUN, …)<\/li>\n<\/ul>\n\n
How to use\u00a0sapply() function in R?<\/h3>\n
> BOD\u00a0\u00a0\u00a0 \u00a0#R built-in dataset, Biochemical Oxygen Demand<\/pre>\n
![\"BOD](\"https:\/\/data-flair.training\/blogs\/wp-content\/uploads\/sites\/2\/2017\/09\/BOD-Time-demand.jpg\")
<\/a><\/p>\nsapply(BOD, sum)<\/pre>\n
>\u00a0sapply(BOD,function(x) 10 * x)<\/pre>\n
x <- array(1:9)\r\n>\u00a0sapply(x,function(x) x * 10)<\/pre>\n
> x <- array(1:9,c(3,3))\r\n> x\r\n>\u00a0sapply(x,function(x) x * 10)\r\n> sapply(c(1:3), function(x) x^2)<\/pre>\n
![\"BOD](\"https:\/\/data-flair.training\/blogs\/wp-content\/uploads\/sites\/2\/2017\/09\/BOD-Time-demand-sapply.jpg\")
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