Which R function shows the structure of an object?

Question

BlackTom AI · Accepted Answer

The R function str() displays the internal structure of an R object, showing its type, class, dimensions, and a compact preview of its contents.

1. Relevant knowledge points and concepts
- str() is a base R function designed for compactly inspecting the structure of any R object (vectors, lists, data.frames, factors, functions, etc.).
- It reports object class, length or dimensions, and the first few elements of each component, which is especially useful for debugging and understanding unfamiliar objects.
- Other related functions include summary(), class(), typeof(), print(), dim(), and dplyr::glimpse(), but each serves a different, more specific purpose.

2. Complete reasoning process step by step
- When you call str(object), R determines the object’s class and type, then prints a concise description: for a data.frame it prints "data.frame": number of observations x number of variables, followed by $variable: type and the first few values; for list it prints the list length and each element’s type and preview.
- This output lets you quickly see nested structures, variable types, and sample values without dumping the entire object.

3. Intermediate steps / examples
- Example: str(iris) yields something like:
  'data.frame': 150 obs. of 5 variables:
  $ Sepal.Length: num 5.1 4.9 4.7 ...
  $ Sepal.Width : num 3.5 3.0 3.2 ...
  etc.
- Example: str(list(a = 1:3, b = "x")) yields:
  List of 2
   $ a: int [1:3] 1 2 3
   $ b: chr "x"

4. Why the correct answer is correct
- The definition and examples above show that str() is specifically implemented to "show the structure of an object" in R—exactly what the question asks.

5. Why other functions are incorrect
- summary() gives summary statistics, not a structural layout.
- class() returns only the object's class.
- typeof() returns the low-level type.
- print() prints the object’s contents (possibly large), not a compact structural summary.
- glimpse() (dplyr) is similar but not base R; the canonical base R function is str().

6. Conclusion
The correct answer is str(), which matches the provided answer.

Which R function shows the structure of an object?单项选择题

类似问题

na is a vector of numeric elements. You do not know how many elements na has. When you run the following, you are returned 1. sum(is.na(na)) If you execute the following, what would be the output? sum(is.na(na[which(is.na(na))] + na)) ==length(na)

Dharma has vector w in her active R session. There are no missing values in w. That is, there is no NA’s in w. She executed the following code: sum(w) == sum(w[which(w)]) R returned (outputted) TRUE on her R console. TRUE/FALSE: w is not a logical vector.

Suppose Jorge typed the following R code in a new R script and executed the entire code. x <- 2 y <- if_else(is.numeric(is.character(x)), 1, 2) y <- x/y What is the resulting value of y?

更多留学生实用工具

智能学习助手

风格化写作助手

论文查重助手

文献引用助手

课堂转译助手

课堂笔记助手

Quiz搜索助手

学校历年真题

智能刷题助手

智能匹配练习

希望你的学习变得更简单