Get full properties of R object

Question

There is a function I have used before to get the full properties of an object in R (I used it before to find out why two dataframes which looked identical failed the checkEquals RUnit check).

The structure (str()) and attributes (attributes()) look identical. Can anyone point me in the right direction as to what the function which shows the full properties of an object is please?

Solution

1. str (with optionally passed vec.len, nhcar.max etc. arguments) should be fine. E.g.:

   > str(mtcars, vec.len=Inf)
   'data.frame':   32 obs. of  11 variables:
    $ mpg : num  21 21 22.8 21.4 18.7 18.1 14.3 24.4 22.8 19.2 17.8 16.4 17.3 15.2 10.4 10.4 14.7 32.4 30.4 33.9 21.5 15.5 15.2 13.3 19.2 27.3 26 30.4 15.8 19.7 15 21.4
    $ cyl : num  6 6 4 6 8 6 8 4 4 6 6 8 8 8 8 8 8 4 4 4 4 8 8 8 8 4 4 4 8 6 8 4
    $ disp: num  160 160 108 258 360 225 360 146.7 140.8 167.6 167.6 275.8 275.8 275.8 472 460 440 78.7 75.7 71.1 120.1 318 304 350 400 79 120.3 95.1 351 145 301 121
    $ hp  : num  110 110 93 110 175 105 245 62 95 123 123 180 180 180 205 215 230 66 52 65 97 150 150 245 175 66 91 113 264 175 335 109
    $ drat: num  3.9 3.9 3.85 3.08 3.15 2.76 3.21 3.69 3.92 3.92 3.92 3.07 3.07 3.07 2.93 3 3.23 4.08 4.93 4.22 3.7 2.76 3.15 3.73 3.08 4.08 4.43 3.77 4.22 3.62 3.54 4.11
    $ wt  : num  2.62 2.88 2.32 3.21 3.44 3.46 3.57 3.19 3.15 3.44 3.44 4.07 3.73 3.78 5.25 5.42 5.34 2.2 1.61 1.83 2.46 3.52 3.44 3.84 3.85 1.94 2.14 1.51 3.17 2.77 3.57 2.78
    $ qsec: num  16.5 17 18.6 19.4 17 20.2 15.8 20 22.9 18.3 18.9 17.4 17.6 18 18 17.8 17.4 19.5 18.5 19.9 20 16.9 17.3 15.4 17.1 18.9 16.7 16.9 14.5 15.5 14.6 18.6
    $ vs  : num  0 0 1 1 0 1 0 1 1 1 1 0 0 0 0 0 0 1 1 1 1 0 0 0 0 1 0 1 0 0 0 1
    $ am  : num  1 1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1 1 0 0 0 0 0 1 1 1 1 1 1 1
    $ gear: num  4 4 4 3 3 3 3 4 4 4 4 3 3 3 3 3 3 4 4 4 3 3 3 3 3 4 5 5 5 5 5 4
    $ carb: num  4 4 1 1 2 1 4 2 2 4 4 3 3 3 4 4 4 1 2 1 1 2 2 4 2 1 2 2 4 6 8 2
   

2. I you'd want to compare the two R objects from line-to-line, you might try to diff the dputed version of the two objects.

   > dput(mtcars, file = 'mtcars')
   > mtcars2 <- mtcars
   > mtcars2$am <- 0
   > dput(mtcars2, file = 'mtcars2')
   > system('diff mtcars mtcars2')
   23,25c23,25
   <     0, 1, 1, 1, 1, 0, 0, 0, 0, 1, 0, 1, 0, 0, 0, 1), am = c(1, 
   <     1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 
   <     0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1), gear = c(4, 4, 4, 3, 
   ---
   >     0, 1, 1, 1, 1, 0, 0, 0, 0, 1, 0, 1, 0, 0, 0, 1), am = c(0, 
   >     0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 
   >     0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0), gear = c(4, 4, 4, 3, 
   

3. Another method might be to check the hashes of the objects or its parts, short example:

   > library(digest)
   > apply(mtcars, 2, digest)
                                  mpg                                cyl 
   "6b33fae3fd79bb2081e21798c7001c1f" "fb8453e241dd708f9b17c412e94ab884" 
                                 disp                                 hp 
   "feae4e282905d11380533c3cfa3fa997" "2afa2fea47856dc4fa23eb543f1d08a4" 
                                 drat                                 wt 
   "345237ccc9e9b4f523ccdfde31e2f7c5" "558e5730ef0af2f50f23fe86363855ed" 
                                 qsec                                 vs 
   "e777220d1d85545fd98767bb39f10967" "16ff5701471198a294b5c45a90dad3ca" 
                                   am                               gear 
   "abf0f4ab68322a6dd0fc078570892202" "7f9bb11d36a531de7ab0d6e71fd532c9" 
                                 carb 
   "793a7b0812e7597d508be29fc432ff49" 
   

   Here you would get the hash for each column in mtcars which could be compared with a similar data frame and see which column differs, e.g.:

   > apply(mtcars, 2, digest) == apply(mtcars2, 2, digest)
     mpg   cyl  disp    hp  drat    wt  qsec    vs    am  gear  carb 
    TRUE  TRUE  TRUE  TRUE  TRUE  TRUE  TRUE  TRUE FALSE  TRUE  TRUE