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Having trouble importing time series temperature data

 
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wattsup



Joined: 16 Feb 2008
Posts: 3

PostPosted: Mon Apr 07, 2008 1:47 am    Post subject: Having trouble importing time series temperature data Reply with quote

Hi,

First let me say I'm overall satisfied with the program, it has been very useful to me in climate science research.

Second, I'm running into a snag due to the way Dplot handles import. I don't think it is a bug, but simply something not envisioned.

The data I use is historical monthly temperature records, which are in the format:

YYYY.mm temp temp temp

Where YYYY.mm would look like this:

1950.1
1950.2
1950.3
...
1950.12
1951.1
1951.2
...

etc

or this:

1950 1
1950 2
1950 3
...
1950 12

The problem is of course that Dplot can't handle using these values for the X axis. So I have to discard these and simply let Dplot handle the data as "months" by automatically figuring out the x axis from the data. This of course leaves me to plot years manually and to have to always set the tick interval on the x axis to 12 so that I can count years.

Unfortunately, I don't have control over the data format as it is provided by the National Weather Service and other agencies, and thus it presents a bit of a quandary as to what to do to handle this better. I run new plots 4-5 times a month, so any sort of solution would be welcome.

Here is sample data file for you to test with:

ftp://ftp.ssmi.com/msu/monthly_time_series/rss_monthly_msu_amsu_channel_tlt_anomalies_land_and_ocean_v03_1.txt
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DPlotAdmin
Site Admin


Joined: 24 Jun 2003
Posts: 2310
Location: Vicksburg, Mississippi

PostPosted: Mon Apr 07, 2008 9:46 am    Post subject: Reply with quote

Yuck Smile

I started to reply that you could use Edit>Operate on X with the dates in the form Y.M. But that won't work because January would be indistinguishable from October. For the Y.M form it's hopeless; I'll need to write a plugin to handle those.

For the space-separated year and month you can still make this work, though it requires a bit of hoop-jumping. Open the file with "Pick columns to Plot" checked. Enter 0 for "Use column _ as X axis" and check the first curve (the year) in the "Use these columns for Y" list (all others should already be checked - leave them checked).

Now use Generate>Y=f(X,Y1,Y2,...) and enter Y=DATE(Y1,Y2,1) from (for this file) X=0 to 350 with an increment of 1.

Click the Erase button and delete the first two curves (year and month).

Select Generate>Switch Independent Variable and select the last curve (which should be labeled DATE(Y1,Y2,1)).

Right-click any of the numbers on the X axis and select "Calendar date".

Wasn't that fun? Smile

DPlot doesn't interpret your column headings correctly, but those are fairly easily entered manually. I'll put all this on my to-do list for a plugin that removes all the tedium above, but I can't promise when that might be available.
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jsc



Joined: 02 Dec 2005
Posts: 222

PostPosted: Mon Apr 07, 2008 10:05 pm    Post subject: Reply with quote

A little work with excel to turn the first two columns into a date with the =date(year,month,day) formula, and then for column labels concatenate the first two rows, would get you a little further than totally manual manipulation. A bit of a macro in excel, or using a macro in a good text editor like UltraEdit would get you 99% there, though not as neatly as David writing a plugin, to be sure!
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wattsup



Joined: 16 Feb 2008
Posts: 3

PostPosted: Tue Apr 08, 2008 9:43 pm    Post subject: Thanks Reply with quote

I'm VERY appreciative of the ideas. Perhaps by making the . separator selectable (I found one using /) but this could go on ad infinitum.

Now for the really ugly one, NASA GISS data:

http://data.giss.nasa.gov/gistemp/tabledata/GLB.Ts+dSST.txt

Any ideas on how to take this train wreck and make a plot of monthly data?
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DPlotAdmin
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Joined: 24 Jun 2003
Posts: 2310
Location: Vicksburg, Mississippi

PostPosted: Tue Apr 08, 2008 10:39 pm    Post subject: Reply with quote

Quote:
Any ideas on how to take this train wreck and make a plot of monthly data?


Please go away Smile

Just kidding. No, there's no easy (or hard) way I can see to import that into DPlot and get it as it is intended. If I personally had an immediate need to plot that data I'd probably import the table into Excel and write a VBA routine to do the dirty work. Long term I'll at least think about creating a file import plugin to handle that arrangement. But please don't expect anything real soon, as my plate is currently overflowing.
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