R devel - Mar 2019 - prettyNum digits=0 not compatible with scientific notation

R developers,
Seems I get a bad result ("%#4.0-1e" in particular) when trying to use
prettyNum digits=0 with scientific notation. I tried on both my Linux box and on
an online R evaluator and saw the same problem, so it's not limited to my
box at least. I see the problem in both R 3.5.3 and R 3.3.2.

options(scipen=-100)
prettyNum(1, digits=0)
[1] "%#4.0-1e"
prettyNum(2, digits=0)
[1] "%#4.0-1e"
prettyNum(1, digits=0, scientific=FALSE) # Works
[1] "1"
prettyNum(1:2, digits=0) # Works
[1] "1" "2"
prettyNum(c(1.1, 2.1), digits=0)
[1] "%#4.0-1e" "%#4.0-1e"
prettyNum(c(1.1, 2.1), digits=1) # Works
[1] "1e+00" "2e+00"
> R.version
               _                           
platform       x86_64-pc-linux-gnu         
arch           x86_64                      
os             linux-gnu                   
system         x86_64, linux-gnu           
status                                     
major          3                           
minor          5.3                         
year           2019                        
month          03                          
day            11                          
svn rev        76217                       
language       R                           
version.string R version 3.5.3 (2019-03-11)
nickname       Great Truth

Thank you, Robert for raising this here !
>>>>> Robert McGehee 
>>>>>     on Thu, 21 Mar 2019 20:56:19 +0000 writes:
    > R developers,
    > Seems I get a bad result ("%#4.0-1e" in particular) when
trying to use prettyNum digits=0 with scientific notation. I tried on both my
Linux box and on an online R evaluator and saw the same problem, so it's not
limited to my box at least. I see the problem in both R 3.5.3 and R 3.3.2.

    > options(scipen= -100)

The above is extreme: You're basically setting an option to
always see non-integer numbers in "scientific" format ..
But read below about what 'digits' means in this case.

    > prettyNum(1, digits=0)
    > [1] "%#4.0-1e"
    > prettyNum(2, digits=0)
    > [1] "%#4.0-1e"
    > prettyNum(1, digits=0, scientific=FALSE) # Works
    > [1] "1"
    > prettyNum(1:2, digits=0) # Works
    > [1] "1" "2"
    > prettyNum(c(1.1, 2.1), digits=0)
    > [1] "%#4.0-1e" "%#4.0-1e"
    > prettyNum(c(1.1, 2.1), digits=1) # Works
    > [1] "1e+00" "2e+00"

I'm the scape goat / culprit /.. : I have worked on tweaking the
formatting of (non integer) numbers in R for a long time, on the
way introducing prettyNum(), also already long ago...
but then it's actually not prettyNum() but rather format() here :

Have you read its help page - *with* care?

If you do, you'd notice that 'digits' is not among the formal
arguments
of prettyNum() *and* that prettyNum() passes all its  `...`  to format().
And if you read  ?format [which then you should to understand 'digits'
!]
you see

  > digits: how many significant digits are to be used for numeric and
  >      complex ?x?.  The default, NULL, uses
?getOption("digits")?.
>      This is a suggestion: enough decimal places will be used so that
  >      the smallest (in magnitude) number has this many significant 
  >      digits, and also to satisfy ?nsmall?.

  > 	  [.....]

So, for the real numbers you use in your example, digits are
*significant* digits as in  'options(digits= *)' or
'print(.., digits= *)'

------ Excursion about 'integer' and format()ing ------------
-- and you now may also understand why   prettyNum(1:2, digits=0)  works
 as you expect: integer formatting behaves differently   ....
 but I acknowledge that the  ?format   help page does not say so
 explicitly yet:  it 'real and complex' numbers for the
 'scientific' argument,  and 'numeric and complex' numbers for
 the 'format' argument.
 If you replac numeric by reald, what this entails (by logic)
 that 'integer' numbers are *not* affected by 'digits' nor 
'scientific'.

 But there's yet more subtlety: 'integer' here means class/type
"integer"
 and not just an integer number, i.e., the difference of  1L and 1 :

  > str(1)
   num 1
  > str(1L)
   int 1
  > str(1:3)
   int [1:3] 1 2 3
  > str(1:3 + 0)
   num [1:3] 1 2 3
  > 
------ end of Excursion{'integer' ..} -------------------------------

Back to real numbers : 'digits' are used as *significant* digits
(and are only a suggestion: format() and prettyNum() ensure
 a common width for their resulting strings so printing will be
nicely aligned), see e.g.

   > format(3.14, scientific=FALSE)
   [1] "3.14"
   > format(3.14*c(1, 1e-7),   scientific=FALSE)
   [1] "3.140000000" "0.000000314"
   > 

So back to your examples : What would you mean with
``0 significant digits'' ? 
It really does not make sense to show *no* significant digits ..

Intuitively, without spending enough time, I'd say that the bug
in format.default() -- which is called by prettyNum() in
this case -- is that it does *not* treat
'digits = 0'  as 'digits = 1'  in this case.  

NB:  digits = 0 has been valid in    options(digits = 0)  etc,
 "forever" I think, possibly inherited from S,  but I don't
 really know and I wonder if we should not  make it invalid eventually
 requiring at least 1.
So we could make it raise a *warning* (and set it to '1') for  now.
What do others think? 

Anyone with S(-PLUS) or Terr or .. who can report if  digits=0
is allowed there and what it does in a simple situation like

  > format(as.integer(2^30), digits=0) # digits not used at all
  [1] "1073741824"
  > format(2^30, digits=0)
  [1] "%#4.0-1e"
  > 


Last but not least:  If you really want to use exponential
format, you should typically use  sprintf() or formatC()  where
you can tweak to get what you want.

Hi,
Thanks for this. To be clear, I did not intend to use scientific notation, I
just happened to stumble upon this when using prettyNum on numbers large enough
that R switched to scientific notation and I noticed the problem. I just made
this artificial example just to show with an example using smaller numbers (and
in case someone on this list redefined their options(scipen) in their .Rprofile
as I do).

Specifically, here's what I wanted to see:
> prettyNum(30000000.9, big.marks=",", digits=0)
[1] "30,000,001"
But got "%#4.0-1e" instead. I was intending to use digits=0 as a way
of rounding at the same time as adding commas, and was meaning to have a zero
significant digit scientific notation thing, which I agree probably doesn't
make sense.

Also, even smaller numbers that don't normally trigger scientific notation
cause the odd output, so maybe this isn't strictly a scientific notation
problem? 
> options(scipen=0)
> 12345.6
[1] 12345.6 # No scientific notation here
> prettyNum(12345.6, digits=0)
[1] "%#4.0-1e"

My "fix" is just to add scientific=FALSE to my prettyNum calls as this
seems to make the problem disappear for me in all cases. However, the odd output
I encountered along the way seemed worthy of comment.

HTH, Robert

-----Original Message-----
From: Martin Maechler [mailto:maechler at stat.math.ethz.ch] 
Sent: Friday, March 22, 2019 5:11 AM
To: Robert McGehee <rmcgehee at walleyetrading.net>
Cc: r-devel at r-project.org
Subject: Re: [Rd] prettyNum digits=0 not compatible with scientific notation

Thank you, Robert for raising this here !
>>>>> Robert McGehee 
>>>>>     on Thu, 21 Mar 2019 20:56:19 +0000 writes:
    > R developers,
    > Seems I get a bad result ("%#4.0-1e" in particular) when
trying to use prettyNum digits=0 with scientific notation. I tried on both my
Linux box and on an online R evaluator and saw the same problem, so it's not
limited to my box at least. I see the problem in both R 3.5.3 and R 3.3.2.

    > options(scipen= -100)

The above is extreme: You're basically setting an option to
always see non-integer numbers in "scientific" format ..
But read below about what 'digits' means in this case.

    > prettyNum(1, digits=0)
    > [1] "%#4.0-1e"
    > prettyNum(2, digits=0)
    > [1] "%#4.0-1e"
    > prettyNum(1, digits=0, scientific=FALSE) # Works
    > [1] "1"
    > prettyNum(1:2, digits=0) # Works
    > [1] "1" "2"
    > prettyNum(c(1.1, 2.1), digits=0)
    > [1] "%#4.0-1e" "%#4.0-1e"
    > prettyNum(c(1.1, 2.1), digits=1) # Works
    > [1] "1e+00" "2e+00"

I'm the scape goat / culprit /.. : I have worked on tweaking the
formatting of (non integer) numbers in R for a long time, on the
way introducing prettyNum(), also already long ago...
but then it's actually not prettyNum() but rather format() here :

Have you read its help page - *with* care?

If you do, you'd notice that 'digits' is not among the formal
arguments
of prettyNum() *and* that prettyNum() passes all its  `...`  to format().
And if you read  ?format [which then you should to understand 'digits'
!]
you see

  > digits: how many significant digits are to be used for numeric and
  >      complex ?x?.  The default, NULL, uses
?getOption("digits")?.
>      This is a suggestion: enough decimal places will be used so that
  >      the smallest (in magnitude) number has this many significant 
  >      digits, and also to satisfy ?nsmall?.

  > 	  [.....]

So, for the real numbers you use in your example, digits are
*significant* digits as in  'options(digits= *)' or
'print(.., digits= *)'

------ Excursion about 'integer' and format()ing ------------
-- and you now may also understand why   prettyNum(1:2, digits=0)  works
 as you expect: integer formatting behaves differently   ....
 but I acknowledge that the  ?format   help page does not say so
 explicitly yet:  it 'real and complex' numbers for the
 'scientific' argument,  and 'numeric and complex' numbers for
 the 'format' argument.
 If you replac numeric by reald, what this entails (by logic)
 that 'integer' numbers are *not* affected by 'digits' nor 
'scientific'.

 But there's yet more subtlety: 'integer' here means class/type
"integer"
 and not just an integer number, i.e., the difference of  1L and 1 :

  > str(1)
   num 1
  > str(1L)
   int 1
  > str(1:3)
   int [1:3] 1 2 3
  > str(1:3 + 0)
   num [1:3] 1 2 3
  > 
------ end of Excursion{'integer' ..} -------------------------------

Back to real numbers : 'digits' are used as *significant* digits
(and are only a suggestion: format() and prettyNum() ensure
 a common width for their resulting strings so printing will be
nicely aligned), see e.g.

   > format(3.14, scientific=FALSE)
   [1] "3.14"
   > format(3.14*c(1, 1e-7),   scientific=FALSE)
   [1] "3.140000000" "0.000000314"
   > 

So back to your examples : What would you mean with
``0 significant digits'' ? 
It really does not make sense to show *no* significant digits ..

Intuitively, without spending enough time, I'd say that the bug
in format.default() -- which is called by prettyNum() in
this case -- is that it does *not* treat
'digits = 0'  as 'digits = 1'  in this case.  

NB:  digits = 0 has been valid in    options(digits = 0)  etc,
 "forever" I think, possibly inherited from S,  but I don't
 really know and I wonder if we should not  make it invalid eventually
 requiring at least 1.
So we could make it raise a *warning* (and set it to '1') for  now.
What do others think? 

Anyone with S(-PLUS) or Terr or .. who can report if  digits=0
is allowed there and what it does in a simple situation like

  > format(as.integer(2^30), digits=0) # digits not used at all
  [1] "1073741824"
  > format(2^30, digits=0)
  [1] "%#4.0-1e"
  > 


Last but not least:  If you really want to use exponential
format, you should typically use  sprintf() or formatC()  where
you can tweak to get what you want.

FWIW, it doesn't seem to be happening on Mac OS:
> format(2^30, digits=0)
[1] "1.e+09"
> prettyNum(12345.6, digits=0)
[1] "1.e+04"

A glibc misfeature?

-pd
> On 22 Mar 2019, at 10:10 , Martin Maechler <maechler at
stat.math.ethz.ch> wrote:
> 
> Thank you, Robert for raising this here !
> 
>>>>>> Robert McGehee 
>>>>>>    on Thu, 21 Mar 2019 20:56:19 +0000 writes:
> 
>> R developers,
>> Seems I get a bad result ("%#4.0-1e" in particular) when
trying to use prettyNum digits=0 with scientific notation. I tried on both my
Linux box and on an online R evaluator and saw the same problem, so it's not
limited to my box at least. I see the problem in both R 3.5.3 and R 3.3.2.
> 
>> options(scipen= -100)
> 
> The above is extreme: You're basically setting an option to
> always see non-integer numbers in "scientific" format ..
> But read below about what 'digits' means in this case.
> 
>> prettyNum(1, digits=0)
>> [1] "%#4.0-1e"
>> prettyNum(2, digits=0)
>> [1] "%#4.0-1e"
>> prettyNum(1, digits=0, scientific=FALSE) # Works
>> [1] "1"
>> prettyNum(1:2, digits=0) # Works
>> [1] "1" "2"
>> prettyNum(c(1.1, 2.1), digits=0)
>> [1] "%#4.0-1e" "%#4.0-1e"
>> prettyNum(c(1.1, 2.1), digits=1) # Works
>> [1] "1e+00" "2e+00"
> 
> I'm the scape goat / culprit /.. : I have worked on tweaking the
> formatting of (non integer) numbers in R for a long time, on the
> way introducing prettyNum(), also already long ago...
> but then it's actually not prettyNum() but rather format() here :
> 
> Have you read its help page - *with* care?
> 
> If you do, you'd notice that 'digits' is not among the formal
arguments
> of prettyNum() *and* that prettyNum() passes all its  `...`  to format().
> And if you read  ?format [which then you should to understand
'digits' !]
> you see
> 
>> digits: how many significant digits are to be used for numeric and
>>     complex ?x?.  The default, NULL, uses
?getOption("digits")?.
>>     This is a suggestion: enough decimal places will be used so that
>>     the smallest (in magnitude) number has this many significant 
>>     digits, and also to satisfy ?nsmall?.
> 
>> 	  [.....]
> 
> So, for the real numbers you use in your example, digits are
> *significant* digits as in  'options(digits= *)' or
> 'print(.., digits= *)'
> 
> ------ Excursion about 'integer' and format()ing ------------
> -- and you now may also understand why   prettyNum(1:2, digits=0)  works
> as you expect: integer formatting behaves differently   ....
> but I acknowledge that the  ?format   help page does not say so
> explicitly yet:  it 'real and complex' numbers for the
> 'scientific' argument,  and 'numeric and complex' numbers
for
> the 'format' argument.
> If you replac numeric by reald, what this entails (by logic)
> that 'integer' numbers are *not* affected by 'digits' nor 
'scientific'.
> 
> But there's yet more subtlety: 'integer' here means class/type
"integer"
> and not just an integer number, i.e., the difference of  1L and 1 :
> 
>> str(1)
>   num 1
>> str(1L)
>   int 1
>> str(1:3)
>   int [1:3] 1 2 3
>> str(1:3 + 0)
>   num [1:3] 1 2 3
>> 
> ------ end of Excursion{'integer' ..}
-------------------------------
> 
> Back to real numbers : 'digits' are used as *significant* digits
> (and are only a suggestion: format() and prettyNum() ensure
> a common width for their resulting strings so printing will be
> nicely aligned), see e.g.
> 
>> format(3.14, scientific=FALSE)
>   [1] "3.14"
>> format(3.14*c(1, 1e-7),   scientific=FALSE)
>   [1] "3.140000000" "0.000000314"
>> 
> 
> So back to your examples : What would you mean with
> ``0 significant digits'' ? 
> It really does not make sense to show *no* significant digits ..
> 
> Intuitively, without spending enough time, I'd say that the bug
> in format.default() -- which is called by prettyNum() in
> this case -- is that it does *not* treat
> 'digits = 0'  as 'digits = 1'  in this case.  
> 
> NB:  digits = 0 has been valid in    options(digits = 0)  etc,
> "forever" I think, possibly inherited from S,  but I don't
> really know and I wonder if we should not  make it invalid eventually
> requiring at least 1.
> So we could make it raise a *warning* (and set it to '1') for  now.
> What do others think? 
> 
> Anyone with S(-PLUS) or Terr or .. who can report if  digits=0
> is allowed there and what it does in a simple situation like
> 
>> format(as.integer(2^30), digits=0) # digits not used at all
>  [1] "1073741824"
>> format(2^30, digits=0)
>  [1] "%#4.0-1e"
>> 
> 
> 
> Last but not least:  If you really want to use exponential
> format, you should typically use  sprintf() or formatC()  where
> you can tweak to get what you want.
> 
> ______________________________________________
> R-devel at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-devel
-- 
Peter Dalgaard, Professor,
Center for Statistics, Copenhagen Business School
Solbjerg Plads 3, 2000 Frederiksberg, Denmark
Phone: (+45)38153501
Office: A 4.23
Email: pd.mes at cbs.dk  Priv: PDalgd at gmail.com