| Re: merge data-array with calender-date-array [message #61647] |
Fri, 25 July 2008 06:03 |
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Bob[3]
Messages: 60
Registered: December 2006
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On Jul 24, 11:47 am, julia.waltersp...@gmail.com wrote:
> p.s. I have monthly averaged data, so 1month = 1 datapoint = 1 date
> (e.g. 1/01/2002)
>
> I don't need to plot ALL of the 99 dates, it would be sufficient if
> only the year (2000, 2001 etc) would be plotted, but not the day and
> month (and the year only ONCE for the following 12 data points). Does
> this avoid the problem with the max of 60 elements? and if yes, how on
> earth is it done? :)
> cheers
> juls
Sounds like you might want to convert your date array to julian date
(as Chris suggestted) after all.
Then use "plot, jdate, data" with tickunits='years', etc. There's
lots of tick keywords, so you should be abble to get a plot similar to
what you describe.
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| Re: merge data-array with calender-date-array [message #61656 is a reply to message #61647] |
Thu, 24 July 2008 08:47  |
julia.walterspiel
Messages: 35
Registered: July 2008
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Member |
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p.s. I have monthly averaged data, so 1month = 1 datapoint = 1 date
(e.g. 1/01/2002)
I don't need to plot ALL of the 99 dates, it would be sufficient if
only the year (2000, 2001 etc) would be plotted, but not the day and
month (and the year only ONCE for the following 12 data points). Does
this avoid the problem with the max of 60 elements? and if yes, how on
earth is it done? :)
cheers
juls
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| Re: merge data-array with calender-date-array [message #61657 is a reply to message #61656] |
Thu, 24 July 2008 08:32 |
julia.walterspiel
Messages: 35
Registered: July 2008
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Member |
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> [Chris I read the OP differently - that what is needed is to place the
> string dates on the axis for the time series plot of the data]
yes Bob, this is what I'm trying to do.
> I think the TICKNAME graphic keyword for your PLOT command may help
> you.
> something like:
> plot, data, xticks=xnum, xtickname=date
> where xnum is the number of dates.
The problem with the tickname is, as far as i understand, that it's a
string array holding only up to 60 elements. My date-array contains 99
dates.
Or am I misunderstanding something?
cheers
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| Re: merge data-array with calender-date-array [message #61662 is a reply to message #61657] |
Thu, 24 July 2008 05:58 |
Bob[3]
Messages: 60
Registered: December 2006
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On Jul 24, 5:29 am, julia.waltersp...@gmail.com wrote:
> the newbie calls out for help again :)
>
> Problem:
> I have two arrays: one with my MODIS-data (float), the second with the
> "matching" calender dates of the data (string, like "01/Jan/2002").
> Say the first number of the "data-array" belongs to the first date of
> the "date-array".
> What's the easiest way to merge those two arrays so that I will be
> able to easily plot the data with the matching dates as x-axis.
>
> Goal/Purpose:
> Plotting a time series of the data with the matching date on the x-
> axis.
>
> probably a super-easy task, but I only come up with rather inelegant
> solutions and I'm sure there's a simple and elegant way to do this.
> Cheers,
> juls
[Chris I read the OP differently - that what is needed is to place the
string dates on the axis for the time series plot of the data]
Juls,
I think the TICKNAME graphic keyword for your PLOT command may help
you.
something like:
plot, data, xticks=xnum, xtickname=date
where xnum is the number of dates.
Bob.
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| Re: merge data-array with calender-date-array [message #61668 is a reply to message #61662] |
Thu, 24 July 2008 03:28 |
Chris[6]
Messages: 84
Registered: July 2008
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Member |
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On Jul 23, 11:29 pm, julia.waltersp...@gmail.com wrote:
> the newbie calls out for help again :)
>
> Problem:
> I have two arrays: one with my MODIS-data (float), the second with the
> "matching" calender dates of the data (string, like "01/Jan/2002").
> Say the first number of the "data-array" belongs to the first date of
> the "date-array".
> What's the easiest way to merge those two arrays so that I will be
> able to easily plot the data with the matching dates as x-axis.
>
> Goal/Purpose:
> Plotting a time series of the data with the matching date on the x-
> axis.
>
> probably a super-easy task, but I only come up with rather inelegant
> solutions and I'm sure there's a simple and elegant way to do this.
> Cheers,
> juls
The first thought that comes to mind is to convert the date strings to
julian dates using a procedure like juldate from the IDL astronomy
user's library. That's kind of clunky since:
1) You have to loop through the date array
2) You have to convert strings like 'jan' to numbers like 1
anyways, it would look like
nrec=n_elements(date_array)
output=fltarr(2,nrec)
output[1,*]=data_array
for i=0L, n_elements(date_array)-1, 1 do begin
date=strsplit(date_array[i],"/",/extract)
case date[1] of
'Jan': month=1
etc etc
endcase
juldate,[float(date[2]),month,float(date[0])],jd
output[0,i]=jd
endfor
This is probably the inelegant solution you are hoping to avoid?
chris
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