Extract Non Null Elements from a List in R

Extract non null elements from a list in R

Here's another option:

Filter(Negate(is.null), x)

Extracting non-null elements from a list of list of data.frames in R

We could use nested lapply

lapply(G, function(x) unlist(lapply(x, `[[`, 'dint'), use.names = FALSE))

#$A
#[1] 1 2 3

#$B
#[1] 1 2 3 4 5 6

and similar for "SD" as well

lapply(G, function(x) unlist(lapply(x, `[[`, 'SD'), use.names = FALSE))

#$A
#[1] 0 1 2

#$B
#[1] 2 3 4 5 3 4

R: removing NULL elements from a list

The closest you'll be able to get is to first name the list elements and then remove the NULLs.

names(x) <- seq_along(x)

## Using some higher-order convenience functions
Filter(Negate(is.null), x)
# $`11`
# [1] 123
# 
# $`13`
# [1] 456

# Or, using a slightly more standard R idiom
x[sapply(x, is.null)] <- NULL
x
# $`11`
# [1] 123
# 
# $`13`
# [1] 456

Get the first non-null value from selected cells in a row

One option with dplyr could be:

df %>%
    rowwise() %>%
    mutate(liv6 = with(rle(c_across(liv:liv5)), values[which.max(values != 0)]))

     MD   liv  liv2  liv3  liv4  liv5  liv6
  <dbl> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl>
1   100     0     6     1     1     0     6
2   200     0     2     1     0     2     2
3   300     1     0     1     0     7     1
4   400     3     4     1     3     9     3
5   500     4     5     1     5    10     4

Extract non null elements from a list in R

Here's another option:

Filter(Negate(is.null), x)

How to extract non-empty values from each column of a dataframe and make a list?

You can use pivot_longer with values_drop_na = T:

library(tidyverse)
df %>% 
  na_if("") %>% 
  pivot_longer(-Date, values_drop_na = T, names_to = "Company", values_to  = "Number")

  Date       Company Number
  <date>     <chr>   <chr> 
1 2020-06-25 B       3     
2 2020-06-25 C       3     
3 2020-06-26 A       2     
4 2020-06-26 C       2     
5 2020-06-27 A       1   

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You can also use pivot_longer and handle empty cells with filter:

df %>% 
  pivot_longer(-Date, names_to = "Company", values_to  = "Number") %>% 
  filter(Number != "")

How to filter out NULL elements of tibble's list column

One possibility also involving purrr could be:

df %>%
 filter(!map_lgl(var2, is.null))

     id var1  var2            
  <int> <chr> <list>          
1     4 B     <tibble [4 × 2]>

Reflecting the properties of is.null(), you can also do:

df %>%
 rowwise() %>%
 filter(!is.null(var2))

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