[R] Summary bug?

[Martin Maechler]

    Alvaro> Hi, It seems that there's a bug in summary, in the
    Alvaro> max. output... but max() alone works fine.

    Alvaro> hw04.dframe$area
    Alvaro> ...
    Alvaro> [41]   1790   1380   1296   2745    798   2306 438649   1481   1559   2450
    Alvaro> ...

    Alvaro> summary(hw04.dframe)
    Alvaro> area       
    Alvaro> Min.   :   798  
    Alvaro> 1st Qu.:  1349  
    Alvaro> Median :  1690  
    Alvaro> Mean   :  6962  
    Alvaro> 3rd Qu.:  2306  
    Alvaro> Max.   :438600  ### should read 438649

    Alvaro> or, to the point,

    Alvaro> summary(hw04.dframe$area)
    Alvaro> Min. 1st Qu.  Median    Mean 3rd Qu.    Max. 
    Alvaro> 798    1349    1690    6962    2306  438600 
    Alvaro>                                         ### should be 438649

    Alvaro> max(hw04.dframe$area)
    Alvaro> [1] 438649
    Alvaro> is.data.frame(hw04.dframe)
    Alvaro> [1] TRUE

There's no bug.  It's a feature -- inherited from S

 > args(summary.default)

or  ?summary    {please read the doc before posting...}
shows you

    function (object, ..., digits = max(3, .Options$digits - 3)) 

I.e. by default,  options(digits = 7) and you get four digits.
Usually with numbers of vastly different size, you get exponential
representation with 4 digits each,

> summary(as.data.frame(x <- c(rnorm(20),pi* 10^c(0:2,5))))
       x             
 Min.   :-2.056e+00  
 1st Qu.:-1.023e+00  
 Median : 2.774e-01  
 Mean   : 1.310e+04  
 3rd Qu.: 1.428e+00  
 Max.   : 3.142e+05  

but
I agree that in the above case it can be quite confusing
as e.g. in the following (just a different random sample)

> summary(as.data.frame(x <- c(rnorm(20),pi* 10^c(0:2,4))))
       x             
 Min.   :   -1.3250  
 1st Qu.:   -0.4386  
 Median :    0.2091  
 Mean   : 1324.0000  
 3rd Qu.:    0.7687  
 Max.   :31420.0000  

-------

"Solution": 
	    
Use  summary(...., digits= 10)


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