To apply a function to multiple parameters, you can pass an extra variable while using any apply function.. sum multiple columns by group with tapply (2) . Apply function to multiple data frames r. Same function over multiple data frames in R, Make a list of data frames then use lapply to apply the function to them all. The Family of Apply functions pertains to the R base package, and is populated with functions to manipulate slices of data from matrices, arrays, lists and data frames in a repetitive way.Apply Function in R are designed to avoid explicit use of loop constructs. Using lapply with two lists. lapply() deals with list and data frames in the input. 2. lapply() function. I have a function that has as inputs userX, Time1, Time2, Time3 and return a data frame with 1 observation and 19 variables. The l in front of apply stands for “list”. lapply returns a list of the same length as X, each element of which is the result of applying FUN to the corresponding element of X. sapply is a user-friendly version and wrapper of lapply by default returning a vector, matrix or, if simplify = "array", an array if appropriate, by applying simplify2array(). It is possible to pass in a bunch of additional arguments to your function, but these must be the same for each call of your function. The challenge is to identify the parts of your analysis that stay the same and those that differ for each call of the function. Assign the result to names and years, respectively. The next functions are using lists as input data… Example 2: lapply() Function. The Apply family comprises: apply, lapply , sapply, vapply, mapply, rapply, and tapply. Hello guys, I have a list L1 of matrix. data.table documentation: Applying a summarizing function to multiple variables sapply(x, f, simplify = FALSE, USE.NAMES = FALSE) is the same as lapply(x, f). tapply works on a vector, for a data.frame you can use by (which is a wrapper for tapply, take a look at the code): > by (df.1 [, c (3: 5)], df.1 $ state, FUN = colSums) df.1 $ state: AA apples cherries plums 111 222 333-----df.1 $ state: BB apples cherries plums -111-222-333 MARGIN argument is not required here, the specified function is applicable only through columns. I want to apply that function to all the observations of the first data frame to make a new data frame with 2000 observations and 19 variables. Defining a function and being explicit about passing the argument in is more flexible than passing the name of a function … Functions and lapply ... You might see this sort of construction where a function is defined but not returned into a variable called an anonymous function. I thought about using lapply, but if I understand correctly, it only takes multiple - tapply function with two arguments . my_list) and the function … Use lapply() twice to call select_el() over all elements in split_low: once with the index equal to 1 and a second time with the index equal to 2. The trick to using lapply is to recognise that only one item can differ between different function calls.. Here are some examples: vars1<-c(5,6,7) vars2<-c(10,20,30) myFun <-function(var1,var2) In Example 2, I’ll illustrate how to use the lapply function. Within the lapply function, we simply need to specify the name of our list (i.e. lapply() always returns a list, ‘l’ in lapply() refers to ‘list’. df.list < - list(df1,df2,) res <- lapply(df.list, function(x) rowMeans(subset(x, select I have multiple data frames and would like to take the same action across an identically named column in each data frame. 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