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Questions tagged [mapply]

R function that applies a function to multiple lists or vector arguments.

R function mapply is a multivariate version of sapply. mapply applies FUN argument to the first elements of each argument, the second elements, the third elements, and so on. Arguments are recycled if necessary.

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applying function across multiple list in R

I have a function that I would like called computeMASE to apply to 3 different lists forecast.list,train.list,test.list all of them have common values (ap,wi). I can use the function individually to the list as shown in the code below, but when I…
forecaster
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Using mapply to calculate the mean of more than one list

The dataset firstList <- list(a = 1:3, b = 4:6) secondList <- list(c = 7:9, d = 10:12) I am trying to calculate the mean of multiple lists with mapply. mapply(mean, firstList, secondList) It did not work because mean only averages its first…
Ragy Isaac
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Using lapply to list percentage of null variables in every column in R

I was given a large csv that is 115 columns across and 1000 rows. The columns have a variety of data, some is character-based, some is integer, etc. However, the data has a LOT of null variables of varying types (NA, -999, NULL, etc.). What I want…
Matthew Rittinghouse
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Using Map with mget yields unexpected output

I have a number of lists :say list1, list2,....and list 100 and function myfun . With these, I can run Map(myfun,list1,list2,...,list100). However, I want to avoid writing all list numbers, and so I tried Map(myfun,mget(paste0("list",1:100))). But,…
user227710
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Using match.call() with mapply

I have a function that basically outputs a boolean condition as a string from the arguments (the details of the function don't matter here) makeClause <-function(Sex=c("NA", "male", "female"), SmokingHx=c("NA", "current", "former",…
AdrienF
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Using an apply function on multiple subsets of a vector

I've been scrounging around for a solution for this for a while, but there doesn't seem to be anything that can solve this seemingly simple problem I'm having. Long story short, I'm looking to run a function on multiple subsets of a vector, but I am…
user3780892
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Is there an efficient alternative to mapply in R?

Here is a sample data and code I am trying to test: mydata<-structure(list(mpg = c(21, 21, 22.8, 21.4), cyl = c(6, 6, 4, 6), disp = c(160, 160, 108, 258), hp = c(110, 110, 93, 110)), .Names = c("mpg", "cyl", "disp", "hp"), class = "data.frame",…
Metrics
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Use mapply() within attr()

I am running the function below, but adist() is not vectorized, so I need to run it using rowwise(). Obviously this is very slow with a large amount of data. In my scenario, I only have current_text and previous_text, and change is generated from…
Adam_G
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Weird behavior of mapply with rep and dplyr pipes in R

I am dealing with strings having two separators "*" and "|", and they are used in strings such as: "3\*4|2\*7.4|8\*3.2" Where the number right before "*" denotes frequency and the float or integer right after "*" denotes value. These value…
Aku-Ville Lehtimäki
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Efficient and fast application of a function to 3D arrays in R

I have a very large 3D array (say 100 x 100 x 10) that I would like to apply a function over for pairwise comparisons. I've tried a number of solutions, using data.table, mapply, etc. I'm maybe naively hoping for faster speedups, and am considering…
Eric Ward
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2 consecutive nested for-loops - Is it possible to optimize with data.table or apply? Added data.table attempt yet to be optimized

I have a data.table made of data.tables as per the dput at the end of this question. I manipulate this data.table of data.tables using the following nested for-loops: test_E2 <- list() for (i in unique(lst_512_32_E2$ID)){ test_E2[[i]] <-…
Akthem
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R apply with a vector parameter

I am trying to apply the ppoibin (poisson binomial probabilities) function from the poibin package to each row in a dataframe. This function takes two parameters: an integer and a vector of probabilities. My data takes the form: p <- matrix(c(0.046,…
Zachary
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How to apply a function to every element in a dataframe in a list and return a dataframe in R?

I have a dataframe which looks like this example (just much larger): Name <- c('Peter','Peter','Peter', 'Ben','Ben','Ben','Mary', 'Mary', 'Mary') var1 <- c(0.4, 0.6, 0.7, 0.3, 0.9, 0.2, 0.4, 0.6, 0.7) var2 <- c(0.5, 0.4, 0.2, 0.5, 0.4, 0.2, 0.1,…
Mina
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Applying custom function to a list of DFs, taking another list as an input - R

I have a list of dfs and a list of annual budgets. Each df represents one business year, and each budget represents a total spend for that year. # the business year starts from Feb and ends in Jan. # the budget column is first populated with the %…
AndrejFlina
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How to replace rownames of a list of dataframes with values from a list of character strings in R?

Let l be a list of two dataframes and n a list of character strings, wherein l and n both have two elements. Also, let the number of rows of each dataframe in l be equal to the length of the vector of character strings in n. l <- list(data.frame(x =…
Dion Groothof
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