R devel - Dec 2000 - some (may be related) problems with windows(rescale=) (PR#794)

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Before reporting 4 problems with windows(rescale=) I want to congrat on R1.2 and
to thank r-developers for quickly adding the rescale workaround to the windows
version.

Happy New Year


Jens Oehlschlaegel


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## windows(rescale="fixed") does not keep original device size 
## (probably device initialization error)
###############################################################################

dev.show <- function(){
	din <- par("din")
	c(width=din[1], height=din[2], aspectratio=din[1]/din[2])
}
width <- 42/2.54
height <- 29.7/2.54
> width
[1] 16.53543
> height
[1] 11.69291
> width/height
[1] 1.414141

> windows(width=width, height=height, rescale="R")
> dev.show()
      width      height aspectratio 
   9.229167    6.385417    1.445351 
> dev.off()
null device 
          1 
> windows(width=width, height=height, rescale="fixed")
> dev.show()
      width      height aspectratio 
   9.229167    6.385417    1.445351 
> dev.off()
null device 
          1 
> windows(width=width, height=height, rescale="fit")
> dev.show()
      width      height aspectratio 
   9.229167    6.385417    1.445351 


## Shouldn't at least rescale="fixed" give the desired device size
and aspect ratio?
## The Help to windows() says:
## Using `"fixed"' will leave
##     the plot size unchanged, adding scrollbars if part of the plot is
##     obscured. This setting also affects the initial re-scaling if the
##     specified window size is too big.   



###############################################################################
## windows(rescale="fit") gives strange character sizes 
## (looks like device initialization error)
###############################################################################


## In the following examples the created devices seem to be equally initialized
with respect to par(din)
## However, with windows(rescale="fit") I observe different par(pin)
and different character sizes in text() and strwidth()

width <- 16.53543
height <- 11.69291

windows(width=width, height=height, rescale="fixed")
par("cex")
plot(0:2,0:2, type="n")
text(1,1,"abc\ndef", cex=2)
text(1,0.5,"fixed", cex=2)
temp <- t(sapply(par(c("din", "fin",
"pin")),c))
colnames(temp) <- c("x", "y")
temp <- rbind(temp, text=c(strwidth("abc\ndef", cex=2),
strheight("abc\ndef", cex=2)))
fixed <- temp

windows(width=width, height=height, rescale="fit")
par("cex")
plot(0:2,0:2, type="n")
text(1,1,"abc\ndef", cex=2)
text(1,0.5,"fit", cex=2)
temp <- t(sapply(par(c("din", "fin",
"pin")),c))
colnames(temp) <- c("x", "y")
temp <- rbind(temp, text=c(strwidth("abc\ndef", cex=2),
strheight("abc\ndef", cex=2)))
fit <- temp

windows(width=width, height=height, rescale="R")
par("cex")
plot(0:2,0:2, type="n")
text(1,1,"abc\ndef", cex=2)
text(1,0.5,"R", cex=2)
temp <- t(sapply(par(c("din", "fin",
"pin")),c))
colnames(temp) <- c("x", "y")
temp <- rbind(temp, text=c(strwidth("abc\ndef", cex=2),
strheight("abc\ndef", cex=2)))
R <- temp

# now compare
fixed
fit
R
> fixed
             x         y
din  9.2291667 6.3854167
fin  9.2291667 6.3854167
pin  8.0666667 4.6604167
text 0.1394628 0.2896737
> fit
              x         y
din  9.22916667 6.3854167
fin  9.22916667 6.3854167
pin  8.79000000 5.7337500
text 0.07935154 0.1122302
> R
             x         y
din  9.2291667 6.3854167
fin  9.2291667 6.3854167
pin  8.0666667 4.6604167
text 0.1394628 0.2896737

> ## It looks like character size of windows(rescale="fit") refers
to originally intended device size of
> ## width=16.53543, height=11.69291 as 
> fit["text", "x"]/R["din",
"x"]*width
[1] 0.1415101
> ## aprox. equal 
> fixed["text", "x"]
[1] 0.1405518


## If we now repeat this procedure with device sizes small enough to avoid
initial rescaling
## the phenomenon disappears

dev.off()
dev.off()
dev.off()

width <- 9.2291667
height <- 6.3854167

windows(width=width, height=height, rescale="fixed")
par("cex")
plot(0:2,0:2, type="n")
text(1,1,"abc\ndef", cex=2)
text(1,0.5,"fixed", cex=2)
temp <- t(sapply(par(c("din", "fin",
"pin")),c))
colnames(temp) <- c("x", "y")
temp <- rbind(temp, text=c(strwidth("abc\ndef", cex=2),
strheight("abc\ndef", cex=2)))
fixed <- temp

windows(width=width, height=height, rescale="fit")
par("cex")
plot(0:2,0:2, type="n")
text(1,1,"abc\ndef", cex=2)
text(1,0.5,"fit", cex=2)
temp <- t(sapply(par(c("din", "fin",
"pin")),c))
colnames(temp) <- c("x", "y")
temp <- rbind(temp, text=c(strwidth("abc\ndef", cex=2),
strheight("abc\ndef", cex=2)))
fit <- temp

windows(width=width, height=height, rescale="R")
par("cex")
plot(0:2,0:2, type="n")
text(1,1,"abc\ndef", cex=2)
text(1,0.5,"R", cex=2)
temp <- t(sapply(par(c("din", "fin",
"pin")),c))
colnames(temp) <- c("x", "y")
temp <- rbind(temp, text=c(strwidth("abc\ndef", cex=2),
strheight("abc\ndef", cex=2)))
R <- temp

# now compare
fixed
fit
R
> fixed
             x         y
din  9.1666667 6.1562500
fin  9.1666667 6.1562500
pin  8.0041667 4.4312500
text 0.1405518 0.3046544
> fit
             x         y
din  9.1666667 6.1562500
fin  9.1666667 6.1562500
pin  8.0041667 4.4312500
text 0.1405518 0.3046544
> R
             x         y
din  9.1666667 6.1562500
fin  9.1666667 6.1562500
pin  8.0041667 4.4312500
text 0.1405518 0.3046544



###############################################################################
## wrong row distances with windows(rescale="fit")
## (looks like device initialization error)
###############################################################################


width <- 16.53543
height <- 11.69291

## as a reference
windows(width=width, height=height, rescale="fixed")
plot(0:2,0:2, type="n")
text(1,1,"there is hardly anything i know for sure\nneither of the future
nor of the past\nnor should i know what to ask\nif the person answering was
you\n\n(Ernst Jandl, stanzen)"
,cex=2)

## Here rows are too close together
windows(width=width, height=height, rescale="fit")
plot(0:2,0:2, type="n")
text(1,1,"there is hardly anything i know for sure\nneither of the future
nor of the past\nnor should i know what to ask\nif the person answering was
you\n\n(Ernst Jandl, stanzen)"
,cex=3)


## Specifying smaller device size thus avoiding initial rescaling 
## makes the problem disappear

width <- 9
height <- 6

windows(width=width, height=height, rescale="fit")
plot(0:2,0:2, type="n")
text(1,1,"there is hardly anything i know for sure\nneither of the future
nor of the past\nnor should i know what to ask\nif the person answering was
you\n\n(Ernst Jandl, stanzen)"
,cex=3)

## Once correctly initialized further rescaling using the mouse does retain
correct distances

dev.off()
dev.off()
dev.off()



###############################################################################
## windows(rescale="fit") destroys aspect ratio 
## (looks like device initialization error)
###############################################################################


dev.show <- function(){
	din <- par("din")
	c(width=din[1], height=din[2], aspectratio=din[1]/din[2])
}
width <- 42/2.54
height <- 29.7/2.54
> width
[1] 16.53543
> height
[1] 11.69291
> width/height
[1] 1.414141


## create a device
> windows(width=width, height=height, rescale="fit")
> dev.show()
      width      height aspectratio 
   9.229167    6.385417    1.445351 

## some resizing of the window BEFORE plot() is called
# par("din") doesn't SEEM to change
> dev.show()
      width      height aspectratio 
   9.229167    6.385417    1.445351 
   
# but in fact calling plot() and dev.show()
> plot(0,0)
> dev.show()
      width      height aspectratio 
   6.321506    5.562500    1.136451 

## now some resizing of the window AFTER plot() is
called
> dev.show()
      width      height aspectratio 
   4.708333    4.500471    1.046187 
> dev.show()
      width      height aspectratio 
   4.718750    3.297956    1.430811 
> dev.show()
      width      height aspectratio 
  3.3255361   4.4375000   0.7494166 
> dev.show()
      width      height aspectratio 
  1.4091170   5.1145833   0.2755096 
> dev.show()
      width      height aspectratio 
  1.4062500   5.1145833   0.2749491 
> dev.show()
      width      height aspectratio 
  0.4701945   3.3854167   0.1388882 
  
## we got very differing aspect ratios
## One reason for that COULD be that the initially intended device sizes are not
kept,
## so that many rescalings cumulate the deviations.
## May be par(din) should not be changed at all (keep the representation layer
stable)
## and only apply rescaling/zooming/scrolling only to the graphical
presentation.



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--please do not edit the information below--

Version:
 platform = i386-pc-mingw32
 arch = x86
 os = Win32
 system = x86, Win32
 status = 
 major = 1
 minor = 2.0
 year = 2000
 month = 12
 day = 15
 language = R

Windows NT 4.0 (build 1381) Service Pack 6

Search Path:
 .GlobalEnv, package:ctest, Autoloads, package:base

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Dear Prof. Brian Ripley,

Thank you for your answer. You convinced me on one important point, but some
issues remain open (revised bug status at the end of this message)
> If these things bother you, could you please supply fixes?  
Given that I don't have much experience in C coding, given that I don't
know any internals of the R graphics engine (where I think a solution would be
best), given that I don't have ever compiled R for Windows (where obviously
the rescale stuff happens), it is currently too expensive for me to attack that.

What I definitely can offer is testing and giving replicable bug reports. 

Also, given that I am not a member of r-devel and that some r-devel don't
think these are clearly bugs, I shrink from producing code that might never make
it into R.
> [snipped]
> Nothing on the help page suggested that the fine details of the R read-only
> parameters will be as you expected after re-scaling the plot, and it never
> occurred to me that anyone would expect so.  
> As they are reported by the R 
> graphics engine (which is used unchanged), I expect they are correct in one
> of the multiple interpretations. 
> [snipped]
Running the risk to repeat me: I am convinced that R like S+ needs a stable
representation layer to which a programmer can refer. This is the layer where we
talk about "let's layout a DIN A3 Paper, let's use 2 inches
margins" and so on and this layer should be independent of actual window
size (presentation layer).

One might whish, that R's grapic parameter do not refer to absolute measures
and divide the device area rather with relative measures: "let's have
10% margins". However, R allows to specify some parameter in absolute
measures (e.g. par(mai=)) and more important some parameters are not free of
absolute measures as par(cex=1) refers to a fixed ont size, not to a fixed
fraction of the device size. Because of this the RO-device feature
par("fin") to me appears not to be an arbitrary size and should be
kept stable.
> Possibly.  I don't think the device size is very interesting after
> rescaling.  What are you using it for?
Well, of course I try to avoid using it. 

Checking this more thoroughly I see that with windows(rescale="fit") I
INDEED CAN IGNORE par("din") as long as I avoid making any
specifications in inches.

Requesting a 16 inch device and getting initially 9 inches CEX is rescaled
appropriately, WITH RESPECT to the intended 16 inch device.

Note that we now introduced a device which looks like 9 inch on screen with too
small fonts, if asked it tells the user 'I am a 9 inch device
(par("din"))' and it does not tell the user 'well, in fact my
original size is 16 inches, don't forget'. But this is OK, the rescaling
basically works. Thus I have to revise the interpretation of the phenomenon
which I observed in comparing the character sizes of the three rescale modes:
What I called "strange character sizes" in
windows(rescale="fit") seems to make sense. It's rather
windows(rescale="fixed") which gives problematic character sizes.

Example
Finding out the necessary par(cex=) which allows a certain amount of text to fit
in a certain fraction of the device size.

=======================windows(rescale="fixed")
does not do rescaling after device initializiation, it's basic idea is to
not change the device size at all.
However, the automatic initial rescaling destroys this idea: if you require a 16
inch device and you get 9 inches, then you can only find out which cex is
optimal for 9 inches but applying the result to a 16 inch device fails.
In short: character size is not correct with respect to those 16 inches we
requested, but is correct with respect to those 9 inches we get instead.
Thus the current implementation does not make sense with devices bigger than the
screen.
=======================
# I intend to layout DIN A3
width <- 16.53543
height <- 11.69291
jandltext <- "there is hardly anything i know for sure\nneither of the
future nor of the past\nnor should i know what to ask\nif the person answering
was you\n\n(Ernst Jandl, stanzen)"
windows(width=width, height=height, rescale="fixed")

# using windows() I find out that with cex=3.2 the following commands give a
text that exacly fills the plot area (horizontally)
par(cex=1)
par(mai=c(0,0,0,0))
plot.new()
par(usr=c(0,2,0,2))
par(c("din","fin","pin"))
par("usr")
text(1,1, jandltext, cex=3.2)

dev.off()
postscript(file = "c:/temp/t.ps", paper="special",
width=width, height=height)

# now applying THE SAME commands gives NOT a text that exacly fills the plot
area (horizontally).
par(cex=1)
par(mai=c(0,0,0,0))
plot.new()
par(usr=c(0,2,0,2))
par(c("din","fin","pin"))
par("usr")
text(1,1, jandltext, cex=3.2)

dev.off()



=====================by constrast 
windows(rescale="fit")
works
=====================
# I intend to layout DIN A3
width <- 16.53543
height <- 11.69291
jandltext <- "there is hardly anything i know for sure\nneither of the
future nor of the past\nnor should i know what to ask\nif the person answering
was you\n\n(Ernst Jandl, stanzen)"
windows(width=width, height=height, rescale="fit")

# using windows() I find out that with cex=5.8 the following commands give a
text that exacly fills the plot area (horizontally)
par(cex=1)
par(mai=c(0,0,0,0))
plot.new()
par(usr=c(0,2,0,2))
par(c("din","fin","pin"))
par("usr")
text(1,1,jandltext, cex=5.8)

dev.off()
postscript(file = "c:/temp/t.ps", paper="special",
width=width, height=height)

# now applying THE SAME commands WORKS
par(cex=1)
par(mai=c(0,0,0,0))
plot.new()
par(usr=c(0,2,0,2))
par(c("din","fin","pin"))
par("usr")
text(1,1,jandltext, cex=5.8)

dev.off()

However repeated resizing of the window does increase the shown font sizes, look
at that:

width <- 8
height <- 6
jandltext <- "there is hardly anything i know for sure\nneither of the
future nor of the past\nnor should i know what to ask\nif the person answering
was you\n\n(Ernst Jandl, stanzen)"
cex <- 2.8

info <- function(){
	user <- strwidth(jandltext, cex=cex, units="user")
	inches <- strwidth(jandltext, cex=cex, units="inches")
	pin <- par("pin")
	din <- par("din")
	data.frame(din=din[1], aspectratio=din[1]/din[2], pintodin=pin[1]/din[1],
struser=user, strinchtopin=inches/pin[1], strinch=inches)
}

windows(width=width, height=height, rescale="fit") # this one serves
as reference for initial window size
windows(width=width, height=height, rescale="fit")
par(cex=1)
par(mai=c(0,0,0,0))
plot.new()
par(usr=c(0,1,0,1))
par(c("din","fin","pin"))
par("usr")
text(0.5,0.5,jandltext, cex=cex)

# Initial measures
print(static <- info())

# now some VERTICAL resizing and bring window back to original size
print(static <- rbind(static, info()))
# we never touched horizontal window size but horiz din differs,
strwidthInInches differs not

# now some VERTICAL resizing and bring window back to original size
print(static <- rbind(static, info()))
# now everything differs
> print(static <- rbind(static, info()))
       din aspectratio pintodin   struser strinchtopin   strinch
1 8.166667    1.326565        1 0.9859694    0.9859694  8.052083 # start
2 6.291905    1.023768        1 1.2797528    1.2797528  8.052083 # after some
vertical resizing
3 8.166667    1.390765        1 1.2908163    1.2908163 10.541667 # after some
horizontal resizing



So here is my revised bug status:

1a) windows(rescale="fixed") does not keep original device size 
1b) windows(rescale="fixed") gives problematic character sizes
(because of 1a)

2) wrong row distances with windows(rescale="fit")
   This phenomenon also observed under different circumstances
   see todays mail to r-help

3a) windows(rescale="fit") destroys aspect ratio
3b) repeated rescaling destroys proper font size as well


Kind regards and best wishes for 2001



Jens Oehlschlägel

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