mapply Questions
3
Solved
I want to calculate growing degree days with several bases, using minimum daily temp, and maximum daily temp. I would like to do this without a for loop if possible to minimize my code.
bases <-...
4
Solved
I have the following data.table
x = structure(list(f1 = 1:3, f2 = 3:5), .Names = c("f1", "f2"), row.names = c(NA, -3L), class = c("data.table", "data.frame"))
I would like to apply a function to...
Spragens asked 21/8, 2014 at 16:26
2
I would like to be able to apply a function to all combinations of a set of input arguments. I have a working solution (below) but would be surprised if there's not a better / more generic way to d...
1
Solved
I understood that data.table is not copied when returned from a function. However, in this particular case it does get copied. Can one explain why?
dt1 <- data.table(a=1)
dt2 <- data.table(b...
Renatorenaud asked 21/1, 2016 at 12:44
3
Solved
I can not use the subset argument of xtabs or aggregate (or any function I tested, including ftable and lm) with mapply. The following calls fail with the subset argument, but they work without:
m...
Multipara asked 29/6, 2019 at 13:36
3
Solved
Using base R, I'd like to use the mapply function on a nested list. For example, in the code below, I'm trying to remove the letter "a" from each element of a nested list. I'd like to replace the l...
2
Solved
I need to programmatically apply different functions to different columns and group by, using data.table.
If the columns and functions were known, I would do like this:
library(data.table)
DT = ...
Abstractionist asked 26/11, 2019 at 21:39
2
Solved
I have the following list and vectors of parameters:
myList <- list(c(3, 0, 1), c(2, 2, 2))
vPar1 <- c(1, 5, 100)
vPar2 <- c(100, 5, 1)
and I'm trying to draw samples from 3 Beta distri...
2
Solved
I would like to pass a function name as an argument in mapply:
f2 <- function(a, b) a + b^2
f <- function(a, b, func) func(a, b)
f(1, 3, f2) ## returns 10
mapply(f2, 1:2, 3) ## returns [1] 1...
4
I want to remove multiple patterns from multiple character vectors. Currently I am going:
a.vector <- gsub("@\\w+", "", a.vector)
a.vector <- gsub("http\\w+", "", a.vector)
a.vector <- g...
1
How do I use MoreArgs properly with chart_Series?
p.txt
s,n
ABBV,AbbVie
BMY,Bristol
LLY,EliLily
MRK,Merck
PFE,Pfizer
sof.r
# R --silent --vanilla < sof.r
library(quantmod)
options("getSymbo...
Humphreys asked 14/7, 2019 at 0:57
2
Solved
Due to memory (and speed) issues, I was hoping to do some computations inside a data.table instead of doing them outside it.
The following code has 100.000 rows, but I'm working with 40 million r...
Brunella asked 12/7, 2019 at 23:58
2
Solved
I want to do what seems a straightforward application of mapply in a data table. I want to multiply a series of data table columns by the value in another column. Here's my function. y is the singl...
Hebraist asked 25/4, 2018 at 16:32
1
Solved
I think I've missed something simple here:
I have a list of data.frames, and a list of row numbers to select.
Something like this:
a <- data.frame(q = c(1,0,0,0),
w = c(1,1,0,0),
e = c(1,1,1...
Soothe asked 5/1, 2018 at 3:27
1
Solved
I have a database of employees, with their manager's id, in long format (one row per employee per month). I would like to add a column that contains their manager's manager's id (or the id of their...
Crapulent asked 29/8, 2016 at 16:16
3
I have a function with two variables x and y:
fun1 <- function(x,y) {
z <- x+y
return(z)
}
The function work fine by itself:
fun1(15,20)
But when I try to use it with two vectors for ...
Bespoke asked 12/2, 2016 at 0:20
1
Solved
Consider this toy function that receives 3 arguments:
toy <- function(x, y, z){
paste(x, y, z)
}
For each argument I have a number of values (not necessarily the same number for each argumen...
5
Solved
So in the course of generating some fake data to answer a map question, I found myself writing the following:
# Generate some fake data
lat <- seq(-90, 90, by = 5)
lon <- seq(-180, 180, by =...
3
Solved
I am trying to use a data.table within a function, and I am trying to understand why my code is failing. I have a data.table as follows:
DT <- data.table(my_name=c("A","B","C","D","E","F"),my_i...
Giesecke asked 25/6, 2015 at 13:34
2
Solved
(Related question that does not include sorting. It's easy to just use paste when you don't need to sort.)
I have a less-than-ideally-structured table with character columns that are generic "item...
Botanomancy asked 25/2, 2015 at 21:40
2
Solved
I am trying to apply functions described here for a set of time series. For this, mapply seems to be a good approach but I guess there is some problem either in defining the function or in using ma...
Runaway asked 24/8, 2014 at 23:6
5
Solved
Say I have two vectors:
a <- c("george", "harry", "harry", "chris", "steve", "steve", "steve", "harry")
b <- c(...
2
Solved
The Vectorize() and the apply() functions in R can often be used to accomplish the same goal. I usually prefer vectorizing a function for readability reasons, because the main calling function is r...
Osterhus asked 1/8, 2014 at 13:40
3
Solved
Let x<-2 in the global env:
x <-2
x
[1] 2
Let a be a function that defines another x locally and uses get:
a<-function(){
x<-1
get("x")
}
This function correctly gets x from th...
Stoneman asked 15/4, 2014 at 14:17
1
Solved
To find the row-wise correlation of two matrices X and Y, the output should have a correlation value for row 1 of X and row 1 of Y, ..., hence in total ten values (because there are ten rows):
X &...
Erythroblastosis asked 25/9, 2013 at 10:25
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