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Re: Excel XLS Import slowdown in version 8

  • To: mathgroup at smc.vnet.net
  • Subject: [mg116257] Re: Excel XLS Import slowdown in version 8
  • From: Lou <lvveen32 at xs4all.nl>
  • Date: Tue, 8 Feb 2011 05:08:20 -0500 (EST)
  • References: <iig75v$rkm$1@smc.vnet.net> <iigpkd$212$1@smc.vnet.net>

On 4 feb, 12:58, Albert Retey <a... at gmx-topmail.de> wrote:
> Hi,
>
> > I have noticed in Mathematica version 8 that Excel (.xls, not the new
> > format) importing is about 3.5 times slower than in version 7. I
> > noticed this because I have a script that reads two sheets from many
> > Excel files that used to take 1.5 seconds per file that now takes
> > around 5.18 seconds per file (AbsoluteTiming). Nothing else is done in
> > that part of the script; it is just a map of an Import command over a
> > list of Excel files. Is anyone else experiencing this slowdown? What
> > is the cause? Are there any remedies?
>
> We have also noticed that the Import of xls-files can be much slower in
> Version 8 than it was in Version 7. Especially if there are plots within
> those files, the import in 8 can be horrible slow, in some cases Import
> becomes completely useless. It looks like it has to do something with
> the plots, but so far I have not found a way to avoid that, e.g. by just
> importing the "Data" element. What has helped in most cases is to delete
> all plots in the xls-files before importing, but of course that is just
> a workaround and might not be a solution if you have many files, as
> seems the case for you...
>
> I would be very interested to hear if anyone has found ways to improve
> the import speed of xls-files in version 8 or switch back to the version
> 7 behaviour...
>
> hth,
>
> albert

It's very very very slow...
I wonder why but it seems Javaw has allot to do ..
try:
In[4]:= writexls = Table[{Range[Random[], 50]}, {x, 1, 1370}];


In[5]:= Export["xl.XLS", writexls]

Out[5]= "xl.XLS"

In[6]:= readxl = Import["xl.XLS"];

On total this short program consumes 2:34.4 (used a stopwatch).. 2,5
minutes!

But...
In[22]:= writexls = Table[{Range[Random[], 50]}, {x, 1, 1369}];


In[23]:= Export["xl.XLS", writexls]

Out[23]= "xl.XLS"

In[24]:= readxl = Import["xl.XLS"];

is ready within 2.4 second..

This is with Mathematica 8. With Mathematica 7 it's slow but not that slow....

This seems to me like a bug somewhere.
I also notice that writing the XLS takes time but reading is much much
much slower.

Kind regards,
Lou


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