是否可以循环遍历多个对象并调用循环中每个对象内的元素

Question

In RI would like to loop over a set of three functions, with the output requiring saving from each function with a name related to the input. This works when applied to one file but I would like to loop over 300+ objects and the function requires specifying elements within the object.

I attempted to create lists of the objects and output names and looping over it with a for loop for a single function (a.ppp) and received an error "Error in i[["X"]] : subscript out of bounds". I am very new to for loops and have limited coding background and am unsure if the loop structure i have created is correct. I have tried multiple options including looping over a dataframe or nesting loops based on some other stack overflow questions.

Some toy data, representing my setup. I have dataframes eg. ag

a <- data.frame(X = c(1, 2, 3),
            Y = c(3,2,1),
            Z = c(4,5,6),
            M = c('A', 'B', 'C'))

I would like to loop over the following three functions.

library(spatstat)

a.ppp = ppp(a$X,a$Y,c(0,3),c(0,3),marks = a$M)
a.nnd = nndist(a.ppp,by=a.ppp$marks)
a.append = cbind(a,a.nnd)

My Attempt has included

listObj = c("a","b","c","d","e","f","g")
list.ppp = c("a.ppp","b.ppp","c.ppp","d.ppp","e.ppp","f.ppp","g.ppp")

for (i in listObj) {
for (j in list.ppp) {

   j=ppp(i[["X"]],i[["Y"]],c(0,12),c(0,12),marks=i[["M"]])
  }
}

I recieved the error:

#Error in i[["X"]] : subscript out of bounds

My Expected results would be a .ppp and .append output for a to g

Just Thought I'd Follow up, Based on the extremely helpful comment from Joran. I have figured the issue out through a modification of his provided code. The code I used was as follows

library(spatstat)

 a <- data.frame(X = c(1, 2, 3),
                            Y = c(3,2,1),
                            Z = c(4,5,6),
                            M = c('A', 'B', 'C')) 

 #Create a list of all the vectors in the environment - Not an ideal method but 
 suitable for the case

 dfs= mget(ls())

 #Create empty lists to be populated during the loop
 dfs_ppp = list()
 dfs_nnd = list()
 dfs_final= list()


for (i in seq_along(dfs)){
 dfs_ppp[[i]] <- ppp(dfs[[i]]$X,dfs[[i]]$Y,c(-1,14),c(-1,14),marks = dfs[[i]]$M)
 dfs_nnd[[i]] = nndist(dfs_ppp[[i]],by=dfs_ppp[[i]]$marks)
 dfs_final[[i]] = cbind(dfs[[i]],dfs_nnd[[i]])  
 }

Answer 1

Try something more like this:

library(spatstat)

a <- data.frame(X = c(1, 2, 3),
                                Y = c(3,2,1),
                                Z = c(4,5,6),
                                M = c('A', 'B', 'C'))

# Put your data frames (a, b, c, etc.) in a list
dfs <- list(x = a,b = a,z = a)

for (i in seq_along(dfs)){
    ppp_obj <- ppp(dfs[[i]]$X,dfs[[i]]$Y,c(0,3),c(0,3),marks = dfs[[i]]$M)
    nnd_obj = nndist(ppp_obj,by=ppp_obj$marks)
    dfs[[i]]$nnd <- nnd_obj
}