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Re: Bug in ExportString?

  • To: mathgroup at smc.vnet.net
  • Subject: [mg87415] Re: Bug in ExportString?
  • From: dh <dh at metrohm.ch>
  • Date: Thu, 10 Apr 2008 02:11:26 -0400 (EDT)
  • References: <ftfee5$bq7$1@smc.vnet.net> <ftfk7f$f9f$1@smc.vnet.net> <fti3s8$ocb$1@smc.vnet.net>


Thank's Szabolcs,

I interpret this as:  for Input PDF can only be used for pictures. The 

manual is rather misleading here, because it says:

"Stores text, fonts, images, and 2D vector graphics in a device- and 

resolution-independent way".

We can only hope that a furure version of import will work better.

Daniel



Szabolcs Horvát wrote:

> dh wrote:

>> Hi,

>>

>> using FullForm on ImportString[ExportString[{1,1}, "PDF"], "PDF"] 

>>

>> //FullForm it is clear that the output is quite different from the 

>>

>> input: {1,1}. Is any documetation available or is this a bug?

>>

>> Daniel

>>

> 

> 

> P_ter wrote:

>  > I did not formulate a good question about:

>  > ImportString[ExportString[" ", "PDF"], "PDF"]

>  > My point is that this gives an image, while

>  > ImportString[ExportString["t", "PDF"], "PDF"]

>  > gives with Inputform a polygon.

>  > I think a space is also text (" "). It has an ASCII place. So, there 

> should be no difference in structure with the letter t.

>  > with friendly greetings,

>  > P_ter

>  >

> 

> 

> Hi Peter and Daniel,

> 

> Why do you think that there is a bug in ImportString or ExportString? 

> For all of " ", "t", or {1,1} I get a result that is an image (Graphics 

> object) and looks the same as the input.  This is what I expect.

> 

> The PDF format (unless it is a "tagged" PDF) does not preserve the 

> structure of text, e.g. it does not preserve spaces and newlines as 

> characters, or the exact order of lines of text (think about multicolumn 

> layouts).  What it does preserve exactly is what the document /looks/ 

> like.  PDF readers can work around these limitations partially, and they 

> make it possible to copy text from untagged PDFs, but the results are 

> usually not perfect ...

> 

> It is possible to extract text from PDFs with Mathematica too, but just 

> like copying with a PDF reader, this is not very reliable ...  Try 

> ImportString[ExportString["abc", "PDF"], {"PDF", "Plaintext"}].  Now try 

> ImportString[ExportString["{1,1}", "PDF"], {"PDF", "Plaintext"}] and see 

> how { and } are mangled.  I get the same result even if I export the PDF 

> to disk and copy the text with Adobe Reader.

> 

> To avoid misunderstandings caused by e.g. version differences, here's 

> the output of the two original examples:

> 

> In[1]:= ImportString[ExportString[" ", "PDF"], "PDF"] // InputForm

> 

> Out[1]//InputForm=

> {Graphics[{Thickness[0.1203858530857692]}, ImageSize -> {6., 12.},

>    PlotRange -> {{0., 5.75}, {0., 12.}}, AspectRatio -> Automatic]}

> 

> In[2]:= ImportString[ExportString["t", "PDF"], "PDF"] // InputForm

> 

> Out[2]//InputForm=

> {Graphics[{Thickness[0.1203858530857692],

>     Style[{Polygon[{{2.091796875, 8.509033203125}, {4.220947265625,

>        8.509033203125}, {4.421722625851167, 8.451835899501459},

>        {4.482421875, 8.303589152176556}, {4.421722625851167,

>        8.156801263831468}, {4.220947265625, 8.09814453125},

>        {2.091796875, 8.09814453125}, {2.091796875, 5.495071589250973},

>        {2.108850370770762, 5.332197101756292}, {2.1600108580830497,

>        5.183257225422544}, {2.2452783369368614, 5.0482519602497264},

>        {2.364652807332199, 4.927181306237841}, {2.516930475494741,

>        4.827340876360347}, {2.7009075476501696, 4.75602628359071},

>        {2.9165840237984852, 4.713237527928927}, {3.1639599039396877,

>        4.698974609375}, {3.366194069710223, 4.7067809227375665},

>        {3.5765993348355423, 4.730199862825267}, {3.7951756993156462,

>        4.7692314296381015}, {4.021923163150536, 4.82387562317607},

>        {4.239915941290354, 4.888295938810949}, {4.4322282486852504,

>        4.956655871914518}, {4.5988600853352235, 5.028955422486776},

>        {4.739811451240271, 5.105194590527724}, {4.893894204462548,

>        5.1688121276143}, {5.0240478515625, 5.107528935888862},

>        {5.080078125, 4.963367506687742}, {5.019378875851167,

>        4.8262102535262645}, {4.762354584333962, 4.657900419123906},

>        {4.553572510003116, 4.568766279999848}, {4.291277149957441,

>        4.476312659593871}, {4.005271056653925, 4.3939634686778035},

>        {3.72535678254955, 4.335142618023468}, {3.4515343276443184,

>        4.299850107630867}, {3.1838036919382304, 4.2880859375},

>        {3.016159801260507, 4.293133587967097}, {2.8572888622951877,

>        4.3082765393683875}, {2.565865839501763, 4.368848344973554},

>        {2.309534623557955, 4.469801354315495}, {2.0882952144637645,

>        4.6111355673942125}, {1.9100633970030552, 4.78668620781212},

>        {1.7827549559596911, 4.990288499171632}, {1.706369891333673,

>        5.221942441472747}, {1.680908203125, 5.481648034715468},

>        {1.680908203125, 8.09814453125}, {0.940258124088035,

>        8.09814453125}, {0.7345219593567602, 8.15621760624392},

>        {0.67236328125, 8.305923782526751}, {0.7345219593567602,

>        8.450960413120136}, {0.940258124088035, 8.509033203125},

>        {1.680908203125, 8.509033203125}, {1.680908203125, 9.6669921875},

>        {1.7389812781189207, 9.867767547726167}, {1.8840181937013618,

>        9.928466796875}, {2.0337240849951357, 9.867767547726167},

>        {2.091796875, 9.6669921875}, {2.091796875, 8.509033203125}}]},

>      Thickness[0.1203858530857692]]}, ImageSize -> {6., 12.},

>    PlotRange -> {{0., 5.75}, {0., 12.}}, AspectRatio -> Automatic]}

> 




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