[R] Show only header of str() function

[Deepayan Sarkar]

On Thu, Sep 2, 2021 at 9:26 PM Enrico Schumann <es using enricoschumann.net> wrote:
>
> On Thu, 02 Sep 2021, Luigi Marongiu writes:
>
> > Hello, is it possible to show only the header (that is: `'data.frame':
> > x obs. of  y variables:` part) of the str function?
> > Thank you
>
> Perhaps one more solution. You could limit the number
> of list components to be printed, though it will leave
> a "truncated" message.
>
>     str(iris, list.len = 0)
>     ## 'data.frame':    150 obs. of  5 variables:
>     ##   [list output truncated]

Or use 'max.level', which is also generally useful for nested lists:

str(iris, max.level=0)
## 'data.frame':    150 obs. of  5 variables:

Best,
-Deepayan

> Since 'str' is a generic function, you could also
> define a new 'str' method. Perhaps something among
> those lines:
>
>     str.data.frame.oneline <- function (object, ...) {
>         cat("'data.frame':\t", nrow(object), " obs. of  ",
>             (p <- length(object)),
>             " variable", if (p != 1) "s", "\n", sep = "")
>         invisible(NULL)
>     }
>
> (which is essentially taken from 'str.data.frame').
>
> Then:
>
>     class(iris) <- c("data.frame.oneline", class(iris))
>
>     str(iris)
>     ## 'data.frame':  150 obs. of  5 variables
>
>     str(list(a = 1,
>              list(b = 2,
>                   c = iris)))
>     ## List of 2
>     ##  $ a: num 1
>     ##  $  :List of 2
>     ##   ..$ b: num 2
>     ##   ..$ c:'data.frame':   150 obs. of  5 variables
>
>
>
>
> --
> Enrico Schumann
> Lucerne, Switzerland
> http://enricoschumann.net
>
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