Check Whether All Elements of a List Are in Equal in R

check whether all elements of a list are in equal in R

How about

allSame <- function(x) length(unique(x)) == 1

allSame(test_true)
# [1] TRUE
allSame(test_false)
# [1] FALSE

As @JoshuaUlrich pointed out below, unique may be slow on lists. Also, identical and unique may use different criteria. Reduce is a function I recently learned about for extending pairwise operations:

identicalValue <- function(x,y) if (identical(x,y)) x else FALSE
Reduce(identicalValue,test_true)
# [1] 1 2 3
Reduce(identicalValue,test_false)
# [1] FALSE

This inefficiently continues making comparisons after finding one non-match. My crude solution to that would be to write else break instead of else FALSE, throwing an error.

Test if all elements of a list (lists themselves) are equal

This is the canonical method for determining whether all items in a list are the same:

length(unique(object))==1

In your case:

> length( unique( eventual.list ) )
[1] 2

> length( unique( eventual.list ) ) == 1
[1] FALSE

The help page for unique might have led one to think that lists would not be handled, until one reflects on this result that surprised me when I encountered it the first time:

 is.vector( eventual.list ) 
[1] TRUE

So lists are technically vectors in R parlance, they're just not 'atomic' vectors, they are "recursive".

>  is.atomic(eventual.list)
[1] FALSE
> is.recursive(eventual.list)
[1] TRUE

Is there a better way to check if all elements in a list are named?

I am not sure if the following base R code works for your general cases, but it seems work for the ones in your post.

Define a function f to check the names

f <- function(lst) length(lst) == sum(names(lst) != "",na.rm = TRUE)

and you will see

> f(x)
[1] TRUE

> f(y)
[1] FALSE

> f(z)
[1] FALSE

Test for equality between all members of list

1) IF the list has only two components as in the question then try this:

identical(some_list[[1]], some_list[[2]])
## [1] TRUE

2) or for a general approach with any number of components try this:

all(sapply(some_list, identical, some_list[[1]]))
## [1] TRUE

L <- list(1, 2, 3)
all(sapply(L, identical, L[[1]]))
## [1] FALSE

3) Reduce This is a bit verbose compared to the prior solution but since there was a discussion of Reduce, this is how it could be jmplemented:

Reduce(function(x, y) x && identical(y, some_list[[1]]), init = TRUE, some_list)
## [1] TRUE

Reduce(function(x, y) x && identical(y, L[[1]]), init = TRUE, L)
## [1] FALSE

r - check is all elements of a list match a vector exactly

We can use lapply :

lapply(list_1, function(x) if(all(x %in% vec_1)) TRUE else setdiff(x, vec_1))

#$x
#[1] TRUE

#$y
#[1] "foo"  "bars"

how can i check if all the elements of list are integers in r?

Try the code below

> all(sapply(List_example, `%%`, 1) == 0)
[1] TRUE

how to see if any element of a list contains only a certain value in R

We may need to wrap with all - loop over the list of matrices with sapply, create a logical expression (x == 0), wrap with all to return a single TRUE/FALSE - if all values excluding NAs (na.rm = TRUE) are 0, this returns TRUE or else FALSe

sapply(my_list, function(x) all(x == 0, na.rm = TRUE))

Test for equality among all elements of a single numeric vector

I use this method, which compares the min and the max, after dividing by the mean:

# Determine if range of vector is FP 0.
zero_range <- function(x, tol = .Machine$double.eps ^ 0.5) {
  if (length(x) == 1) return(TRUE)
  x <- range(x) / mean(x)
  isTRUE(all.equal(x[1], x[2], tolerance = tol))
}

If you were using this more seriously, you'd probably want to remove missing values before computing the range and mean.

R: how to check if vector elements are the same

You can simply check the number of unique values:

length(unique(ranks)) == 1

Find out if there's equal elements in a list in a column in R

Here's a function that, I think, deals with all of the specifications in the comments. It should find any set of values that always show up together, whether pairs, triplets, etc... To showcase this, I modified the data somewhat.

example <- tibble::tribble(
  ~x, 
  "a,d,e",
  "a,e,d", 
  "b,e,f,a,c", 
  "a,e", 
  "b,c,d,f"
)

find_equal <- function(data){
  all_vals <- strsplit(data, ",") %>% unlist %>% unique
  library(stringr)
  dums <- sapply(all_vals, function(x)str_detect(data, x))
  eq <- lapply(1:ncol(dums), function(i)apply(dums[,-i], 2, function(x)all(dums[,i] == x)))
  names(eq) <- all_vals
  out <- sapply(1:length(eq), function(i){
    if(any(eq[[i]]))paste(sort(c(names(eq)[i], names(eq[[i]])[which(eq[[i]])])), collapse=",")
    else{NULL}
  })
  out <- unlist(out)
  unique(out)
}

find_equal(example$x)
# [1] "a,e"   "b,c,f"

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