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From |
"Nick Cox" <n.j.cox@durham.ac.uk> |

To |
<statalist@hsphsun2.harvard.edu> |

Subject |
RE: AW: st: RE: Graphing time on the x axis |

Date |
Tue, 22 Dec 2009 11:48:20 -0000 |

As I understand it, you have subtracted one date-time from another, but the result is not itself a date-time. It is an elapsed time, and Stata lacks any support specific to elapsed times. So, for example, 1 (elapsed) day and 2 (elapsed) days look identical in terms of clock time, as you already know. . di %tc_HH:MM:SS 24 * 60 * 60 * 1000 00:00:00 . di %tc_HH:MM:SS 48 * 60 * 60 * 1000 00:00:00 Conversely, the difference between 21 December 2009 and 22 December 2009 is not as indicated by . di %d mdy(12,22,2009) - mdy(12,21,2009) 02jan1960 But just 1 day. In short, applying date-time formats to elapsed times at best tells only part of the story and at worst gives you nonsense. That shouldn't be a surprise when you think about it. For elapsed times, you need to create your own code (setting aside earlier user-written efforts best consigned to history). In essence, Stata carries no knowledge forward of how your variables were calculated. As I guessed earlier in the thread, you assigned a format that is no use for graphing, as it does not distinguish elapsed times except in terms of what a clock would show. I asked earlier for you to -summarize- the values of your variables, but I've not seen any results. From your graph it seems that the data fall into two distinct subsets, times less than 1 day and times more than 1 day. I can't suggest why that is, but only looking at your data closely can tell you if there is some error or this does in fact make sense. As I suggested earlier, it is likely that you need to create your own axis labels, using a conversion from milliseconds to hours. -mylabels- from SSC is there to help. Nick n.j.cox@durham.ac.uk moleps islon The measurements have taken place at -clock-. However trying to twoway graph with clock along the x axis resulted in the problem with changing dates and jumps on the graph. I tried to cricumvent this by subtracting clock with the first clock-value.. but as you see it leaves me with the same problem. I´m sure there is someway around this... .format x %9.0g . l x clock in 1/5 +------------------+ | x clock | |------------------| 1. | 0 18:46:46 | 2. | 18000 18:47:04 | 3. | 30000 18:47:16 | 4. | 36000 18:47:22 | 5. | 66000 18:47:52 | +------------------+ M On Mon, Dec 21, 2009 at 9:58 PM, Martin Weiss <martin.weiss1@gmx.de> wrote: > > <> > > I am not sure why you - format x %td_HH:MM:SS- while I formatted - format x > %tc_HH:MM:SS-. What happens when you > > *** > format x %9.0g > l in 1/5 > *** > > > HTH > Martin > > > -----Original Message----- > From: owner-statalist@hsphsun2.harvard.edu > [mailto:owner-statalist@hsphsun2.harvard.edu] On Behalf Of moleps > Sent: Montag, 21. Dezember 2009 21:51 > To: statalist@hsphsun2.harvard.edu > Subject: Re: AW: st: RE: Graphing time on the x axis > > To me there doesnt seem to be any difference between the sets, but doing the > following explains why the graph looks as it does. However I do not > understand how this comes about or how I can rectify it... > > > > . list x in 1/5 > > +----------+ > | x | > |----------| > 1. | 00:00:00 | > 2. | 00:00:18 | > 3. | 00:00:30 | > 4. | 00:00:36 | > 5. | 00:01:06 | > +----------+ > > . sort x > > . list x in 1/5 > > +----------+ > | x | > |----------| > 1. | 05:10:24 | > 2. | 05:10:30 | > 3. | 05:10:36 | > 4. | 05:10:42 | > 5. | 05:10:48 | > +----------+ > > > M > > > > On 21. des. 2009, at 21.18, Martin Weiss wrote: > >> >> <> >> >> How is your dataset different from the one I am playing with? >> >> >> ******* >> clear* >> set obs 1000 >> set seed 10234 >> >> gen x=(_n-1)*6000 >> >> format x %tc_HH:MM:SS >> >> gen mean_amp =rnormal() >> gen meanp =rnormal() >> >> gen byte c7=(runiform()<.2)+1 >> >> compress >> >> tw (line mean_amp x if c7==1) /* >> */ (line mean_amp x if c7==2) /* >> */ (line meanp x if c7==1) /* >> */ (line meanp x if c7==2) >> ******* >> >> >> HTH >> Martin >> >> -----Original Message----- >> From: owner-statalist@hsphsun2.harvard.edu >> [mailto:owner-statalist@hsphsun2.harvard.edu] On Behalf Of moleps >> Sent: Montag, 21. Dezember 2009 20:32 >> To: statalist@hsphsun2.harvard.edu >> Subject: Re: AW: st: RE: Graphing time on the x axis >> >> picture of the graph >> >> http://www.flickr.com/photos/45805518@N04/?saved=1 >> >> commands >> >> >> >> >> >> . format x %td_HH:MM:SS >> >> . list x in 1/5 >> >> +----------+ >> | x | >> |----------| >> 1. | 00:00:00 | >> 2. | 00:00:18 | >> 3. | 00:00:30 | >> 4. | 00:00:36 | >> 5. | 00:01:06 | >> +----------+ >> . tw (line mean_amp x if c7==1) (line mean_amp x if c7==2) (line meanp > x >> if c7==1) (line meanp x >>> if c7==2) >> >> Regards, >> >> M >> >> >> >> On 21. des. 2009, at 19.57, Martin Weiss wrote: >> >>> >>> <> >>> >>> >>> You should probably reproduce the problem with a dataset shipped with >> Stata. >>> Is the time variable numeric or string? >>> >>> >>> >>> HTH >>> Martin >>> >>> >>> -----Ursprüngliche Nachricht----- >>> Von: owner-statalist@hsphsun2.harvard.edu >>> [mailto:owner-statalist@hsphsun2.harvard.edu] Im Auftrag von moleps >>> Gesendet: Montag, 21. Dezember 2009 19:48 >>> An: statalist@hsphsun2.harvard.edu >>> Betreff: Re: st: RE: Graphing time on the x axis >>> >>> Maybe I was unclear in my description of the graph, but i dont think it > is >> a >>> scale or label question. The problem is that given the coordinates > (00:00, >>> 2.3) (05:36,1.9) (07:20,3.1) (18:58,2.9) they are not graphed in that >> order; >>> Instead I have (07:20,3.1) (18:58,2.9) (00:00, 2.3) (05:36,1.9) ... >>> >>> Regards >>> >>> M >>> >>> >>> On 21. des. 2009, at 13.45, Nick Cox wrote: >>> >>>> Clearly you need to specify your own. >>>> >>>> A convenience tool is -mylabels- from SSC. You just need to specify the >>> conversion from Stata's underlying scale, presumably milliseconds, to > your >>> desired scale, which may be hours (you don't say what you want instead). >> See >>> the help for more. >>>> >>>> Nick >>>> n.j.cox@durham.ac.uk >>>> >>>> moleps islon >>>> >>>> I´ve created a variable, time, for two measurements that both have >>>> been subtracted from the starting time of the measuerement so that the >>>> two start out with time 00:00:00 and I have measurements every 10 >>>> sec. However after doing a twoway plot the starting point is not >>>> 00:00:00. Instead I have these tick marks and values along the x >>>> axis:: 07:20--12:53--18:58--00:00--05:36.... Any ideas? * * For searches and help try: * http://www.stata.com/help.cgi?search * http://www.stata.com/support/statalist/faq * http://www.ats.ucla.edu/stat/stata/

**Follow-Ups**:**Re: AW: st: RE: Graphing time on the x axis***From:*moleps islon <moleps2@gmail.com>

**References**:**st: Graphing time on the x axis***From:*moleps islon <moleps2@gmail.com>

**st: RE: Graphing time on the x axis***From:*"Nick Cox" <n.j.cox@durham.ac.uk>

**Re: st: RE: Graphing time on the x axis***From:*moleps <moleps2@gmail.com>

**Re: AW: st: RE: Graphing time on the x axis***From:*moleps <moleps2@gmail.com>

**Re: AW: st: RE: Graphing time on the x axis***From:*moleps <moleps2@gmail.com>

**Re: AW: st: RE: Graphing time on the x axis***From:*moleps islon <moleps2@gmail.com>

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