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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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Parallelize user-defined function using apply family in R

I have a script that takes too long to compute and I'm trying to paralellize its execution. The script basically loops through each row of a data frame and perform some calculations as shown below: my.df = data.frame(id=1:9,value=11:19) sumPrevious…
Victor
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How to combine rapply() and mapply(), or how to use mapply/Map recursively?

I was wondering if there's a simple way to combine the functions of rapply( , how = "replace") and mapply(), in order to use mapply() on nested lists recursively. For instance, I have two nested lists: A = list(list(c(1,2,3), c(2,3,4)),…
shenglih
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How to specify which arguments to be iterated in mapply in R

I am new to R, hence I am new to the apply functions. I haven't found the answer to this question anywhere, even though I have a (not so elegant) way of solving it. Consider this dummy code: my.fun <- function(vector1, vector2, vector3 = NULL) { …
jose
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Using mapply with mean function on a matrix

I wish to calculate the mean of adjacent values in each column (or row) of a matrix (e.g. mean of [1,1] and [2,1], [2,1] and [3,1], [3,1] and [4,1]) and to apply this across all columns. I have tried to use the mapply function (to avoid using a for…
PDN
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Applying some functions to multiple objects

I am on Mac OS 10.10 with R 3.1.1 Suppose I have the following data frames a and b with the same attributes: a<- structure(list(X1 = 1:5, X2 = 6:10), .Names = c("X1", "X2"), row.names = c(NA, -5L), class = "data.frame") b<- structure(list(X1 =…
mallet
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R - Apply function with different argument value for each row/column of a matrix

I am trying to apply a function to each row or column of a matrix, but I need to pass a different argument value for each row. I thought I was familiar with lapply, mapply etc... But probably not enough. As a simple example : >…
RFen
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How to get sum of the list using mapply in r

I have a list of 100 elements, and each element contains 431 elements. i want to use mapply to sum the values from each list. For example, say I have a list of 5 elements, but each element has another 5 elements. > o [[1]] [1] 1 2 3 4 5 [[2]] [1]…
user1828605
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Efficiently counting numbers falling within each range of numbers

I'm looking for a faster solution to the problem below. I'll illustrate the problem with a small example and then provide the code to simulate a large data as that's the point of this question. My actual problem size is of list length = 1 million…
Arun
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How to apply a function on each row of a tibble and a nested list of data frames

I have the following tibble and a nested list of data frames: >source # A tibble: 6 × 2 lon lat 1 6.02 55.1 2 6.02 55.0 3 6.02 54.9 >dest [[1]][[1]] lon lat 1 54.98908 6.900084 2 54.92777 6.772623 3 …
Andreas
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FALSE vs. F: Error mapply's SIMPLIFY argument: in SIMPLIFY=F

This Question refers to this Is there a best way to append a list values to a sublist of a list in R?. One of the solution is this: a <- list(3,5,7) l <- list(c(1,2,3), c(2,1,4), c(4,7,6)) mapply(c, l, a, SIMPLIFY=F) If I try to apply it on my…
TarJae
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Extracting elements from a nested list to a data.matrix

I have a list of 2 elements that each has 3 elements. In every 3 elements, there is a list of length 2 nested elements so that each includes a tibble with rows and columns. tibbles' dimension is fixed for rows but the columns are different from the…
Maya_Cent
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R: using mapply for a function of two vectors

I have an R function that calculates the Hamming distance of two vectors: Hamming = function(x,y){ get_dist = sum(x != y, na.rm=TRUE) return(get_dist) } that I would like to apply to every row of two matrices M1, M2 without using a for loop. What I…
Max
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Ignoring NA in R across multiple columns of Datafrme using na.omit or NA.RM and mapply

I have a dataframe that looks somethings like this: SampleNo Lab1 Lab2 Lab3 lab4 lab5 lab6 lab7 lab8 lab9 lab10 1 59.84 60.59 60.39 60.29 60.19 60.32 60.24 60.3 60.43 NA 2 59.78 60.19 60.16 60.23 …
Spooked
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How to loop through mapply in R?

I am trying to concatenate strings using mapply function in R. However, I want one of the strings to be variable in mapply function. I have a snippet of my code…
user86907
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Fetch daily data for each variable using mapply

I've a function which objective is to fetch daily data for each variable on a column on a data.frame. Range is a complete month, but could be any other range. My df has a column unit_id, so I need my function to take the first id of col unit_id and…
Omar Gonzales
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