Subset sublists of nested list by vector condition-CodePudding

I have a nested list list1:

list1 <- list(Alpha = structure(list(sample_0 = c(3, NA, 7, 9, 2),
                                     sample_1 = c(NA, 3, 5, 4, NA),
                                     sample_2 = c(7, 3, 5, NA, NA)),
                                row.names = c(NA, -5L),
                                class = c("tbl_df", "tbl", "data.frame")),
              Beta = structure (list(sample_0 = c(2, 9, NA, 3, 7),
                                     sample_1 = c(3, 7, 9, 3, NA),
                                     sample_2 = c(4, 2, 6, 4, 6)),
                                row.names = c(NA, -5L),
                                class = c("tbl_df", "tbl", "data.frame")),
              Gamma = structure(list(sample_0 = c(NA, NA, 4, 6, 3),
                                     sample_1 = c(3, 5, 3, NA, 2)),
                                row.names = c(NA, -5L),
                                class = c("tbl_df", "tbl", "data.frame")),
              Delta = structure(list(sample_0 = c(3, NA, 7, 9, 2),
                                     sample_1 = c(3, 8, 5, 4, 9)),
                                     row.names = c(NA, -5L),
                                     class = c("tbl_df", "tbl", "data.frame")))

I needed to change one Column to a factor level, as follows (is there a more elegant way to do that than using a for loop?):

for (i in names(list1)) {
  list1[[i]]$sample_1 <- list1[[i]]$sample_1 %>% as.numeric() %>% 
    cut(breaks=c(0, 2, 4, 5, 8, 10),
        labels=c("-", " ", "  ", "   ", "    "), right = TRUE, na.rm = TRUE)
 }

I now would like to keep only the sublists that contain at least level " " (or " ") in sample_1...

sapply(sapply(list1, `[`, "sample_1"), unique)
$Alpha.sample_1
[1] <NA>          
Levels: -              

$Beta.sample_1
[1]                <NA>
Levels: -              

$Gamma.sample_1
[1]           <NA> -   
Levels: -              

$Delta.sample_1
[1]                    
Levels: -

... and all the other elements of the same sublist in a new list2. The desired result would look as follows:

list1
$Beta
# A tibble: 5 x 3
  sample_0 sample_1 sample_2
     <dbl> <fct>       <dbl>
1        2                 4
2        9                 2
3       NA                 6
4        3                 4
5        7 NA              6
    
$Delta
# A tibble: 5 x 2
  sample_0 sample_1
     <dbl> <fct>   
1        3         
2       NA         
3        7         
4        9         
5        2

I believe I would have to convert the vector to as.integer, but I can't come up with the solution.

CodePudding user response：

You could define what you want to do in a function myFun, use it in lapply and subset the result for nrow > 0.

myFun <- \(x) {
  x$sample_1  <- with(x, cut(sample_1, breaks=c(0, 2, 4, 5, 8, 10),
                     labels=c("-", " ", "  ", "   ", "    "), 
                     right=TRUE, na.rm=TRUE))
  x[x$sample_1 %in% c("   ", "    "), ]
}


res <- lapply(list1, myFun)
res[sapply(res, nrow) > 0]
# $Beta
#   sample_0 sample_1 sample_2
# 2        9                 2
# 3       NA                 6
# 
# $Delta
#   sample_0 sample_1
# 2       NA         
# 5        2         
#

CodePudding user response：

A little function sapply can help:

contains_3plus <- function(greek_letter){
    ("   " %in% greek_letter$sample_1) | ("    " %in% greek_letter$sample_1)
}


list1[which(sapply(list1, contains_3plus))]

# $Beta
# # A tibble: 5 × 3
# sample_0 sample_1 sample_2
# <dbl> <fct>       <dbl>
#   1        2                 4
# 2        9                 2
# 3       NA                 6
# 4        3                 4
# 5        7 NA              6
# 
# $Delta
# # A tibble: 5 × 2
# sample_0 sample_1
# <dbl> <fct>   
#   1        3         
#   2       NA         
#   3        7         
#   4        9         
#   5        2