关于运算符.&.与.|.的定义及功能咨询

Hey there! Great question—these two operators are niche but handy, and they’re most commonly associated with the R programming language. Let’s break down exactly what they do:

These are element-wise short-circuit logical operators—a less common but useful variation of R’s standard logical operators. Unlike R’s &&/|| (which only evaluate the first element of vectors) or &/| (which evaluate all elements without short-circuiting), .&. and .|. combine element-wise evaluation with short-circuit behavior.

.&. (Element-wise Short-circuit AND) #

• Core Function: For each pair of elements across input vectors, it returns TRUE only if both elements are TRUE. The key twist is short-circuiting: if the first element in a pair is FALSE, it skips evaluating the second element entirely (since the result will be FALSE regardless). This saves computation time when the second expression is resource-heavy.
• Example Comparison:

  # Standard & evaluates all elements, even when first is FALSE
  c(FALSE, TRUE) & (print("Computed!"); c(TRUE, FALSE))
  # Output: Prints "Computed!" twice, returns [1] FALSE FALSE
  
  # .&. short-circuits the first element pair
  c(FALSE, TRUE) .&. (print("Computed!"); c(TRUE, FALSE))
  # Output: Prints "Computed!" once, returns [1] FALSE FALSE
  

.|. (Element-wise Short-circuit OR) #

• Core Function: For each pair of elements across input vectors, it returns TRUE if either element is TRUE. Again, short-circuiting applies here: if the first element in a pair is TRUE, it skips evaluating the second element (since the result will be TRUE regardless).
• Example Comparison:

  # Standard | evaluates all elements, even when first is TRUE
  c(TRUE, FALSE) | (print("Computed!"); c(TRUE, FALSE))
  # Output: Prints "Computed!" twice, returns [1] TRUE FALSE
  
  # .|. short-circuits the first element pair
  c(TRUE, FALSE) .|. (print("Computed!"); c(TRUE, FALSE))
  # Output: Prints "Computed!" once, returns [1] TRUE FALSE
  

Key Note #

Keep in mind these operators aren’t universal across all languages—they’re specific to R (often used in tidyverse/rlang contexts). Don’t confuse them with R’s &&/||, which only check the first element of vectors and return a single boolean value, not an element-wise vector.

内容的提问来源于stack exchange，提问作者anonon