Re: [ROOT] X label for time

From: Damir Buskulic (buskulic@lapp.in2p3.fr)
Date: Mon Jun 11 2001 - 12:16:01 MEST


Hi Harufumi,

The behaviour you are seing is probably due to the fact that you
converted dates like January 1st 00:00 to UCT seconds. If you do that on
many years, there could be some problems because all the years do not
have the same length in seconds.
On the other hand, the axis itself is supposed to be linear, which is
causing some small shifts on the exact date of the scale ticks. The
ticks are linearly placed, but the real year start is not.

To overcome this, one simple way is to add a small amount to the
abscissa of each point in seconds. For example, if your axis shows
years, just add a few hours or days to each point. This will not change
what you see on the screen (well, shift the ticks by < 1%), but give you
what you expect.

I intend to do this automatically, I mean round the date displayed, not
shift the ticks, but didn't yet find time to do it.

Cheers

Damir
 
Harufumi Tsuchiya wrote:
> 
> I am now trying to display some data between 1975 and 2001 using
> ROOT(versinon 3.01/05). But, I noticed that relation between
> X labels and X ticks was strange. Please look attached gif file.
> Although X ticks increase by 5, X label does not increase correctly.
> 
> I am trying to read the data such as following.
> 
> year month
> 1975 1
> 1975 2
> 1975 3
> 1975 4
>   :
>   :
>   :
> 2001 3
> 2001 4
> 2001 5
> 
> And I converted these time data into seconds from Jan. 1st, 1975.
> 
> I found that similar problem was discussed in RootTalk previously,
> searching previous mails at http://root.cern.ch/root/Search.phtm using
> keyword "time axis".
> 
> Does this time label problem exist in the latest ROOT ? or
> Is it resolved already ?
> 
> Pleae tell me.
> 
> Thanks for your help
> 
> Harufumi
> 
> 
> 
>   ------------------------------------------------------------------------
>                     Name: axis_date.gif
>    axis_date.gif    Type: GIF Image (image/gif)
>                 Encoding: base64

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| Damir Buskulic                  | Universite de Savoie/LAPP       |
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