Graphing

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Sun, 08/11/2013 - 05:51 pm

Hello,

I'm using Igor Pro to graph a few parameters against time. However, each data file can only be 24 hours long due to the logging computer which I'm using.

When I try to represent a graph which goes over 24 hours I need to be able to copy and paste the data from one table (of one file) to another table in another file to make a complete dataset and then form a graph from there. However, when I do this the graph only responds to time and not the date and the latest data is displayed as the earlier portion on the graph. I've tried changing the table from 'time' to 'time date' as well as including the date in the table in order to achieve the correct time sequence of when the data was gathered. However the data is still in an incorrect order.

Any help for graphing these datasets would be very much appreciated!
Quote:
When I try to represent a graph which goes over 24 hours I need to be able to copy and paste the data from one table (of one file) to another table in another file to make a complete dataset and then form a graph from there.


In order to diagnose this I would need more information about what is being stored and how you are pasting the data. For example:

  • How are your getting your data into Igor

  • Is your data waveform data or XY data

  • Does your data represent date/time or elapsed time?

  • Exactly how are you copy/pasting the data?


    • Date/time data is stored in Igor as seconds since 1904-01-01 and when displayed in a table using date/time format will show a valid date and a valid time.

    Elapsed time is stored as seconds from some arbitrary starting point. When displayed in a table using date/time format the date will appear as 1904-01-01.

    I think it would be best if you would post your two files (I assume they are Igor experiment files) and also list the precise steps that you are taking to copy/paste the data. Then I should be able to diagnose the problem.

August 11, 2013 at 06:59 pm - Permalink

These are two of the files, 013_08_05_New_system_copper_iris_No_buffer_24h_test_105_degrees is first in the series (data in table 6).
From the second experiment (data in table 7) I create a table which has data for; H2O, D_DH, D_1618 and TIMEW, Then I copy the data and paste it down the bottom of the first experiment table (table 6 from the 1st experiment) . I'm getting the data into IGOR through loading waves and then saving it as an experiment. I think the data is stored as elapsed time, but I'm not 100% sure. I also think that it's XY daya rather than waveform.
2013_08_05_New_system_copper_iris_No_buffer_24h_test_105_degrees.pxp 2013_08_06_New_system_copper_iris_No_buffer_24h_test_105_degrees_pt2.pxp

August 11, 2013 at 08:31 pm - Permalink

Your data is XY data with TimeW supplying X and representing elapsed time from some arbitrary time0.

Your TimeW wave in Table6 is a number of seconds since some arbitrary time0 and thus is elapsed time. To see this I changed the column format from time to General (choose Table->Format->General). Then I see this for the first point: 66095.3

This displays as time as 18:21:35.

By contrast, the following command shows 2013-08-11 18:21:35 as a date/time value as stored by Igor (seconds since 1904-01-01):
Print/D Date2Secs(2013,08,11) + 18*60*60 + 21*60 + 35


This prints 3459090095 and, if displayed in a table using date/time format, shows as 2013-08-11 18:21:35.

Your TimeW wave in Table7 is a also number of seconds since some arbitrary time0 and thus is elapsed time. The first point displayed in time format shows as 00:00:06 and as General format shows as 6. That is, it represents 6 seconds from some arbitrary time0.

If you expect the TimeW in Table7 to represent a later time than in Table6 then you need to add something to TimeW in Table7. For example, executing this command in the command line adds 24 hours:
TimeW += 1 * 24 * 60 * 60   // Add number of seconds in 1 day


Now the first point in TimeW in Table7 appears as 24:00:06.

If you now copy TimeW, along with the other columns, in Table7 and paste in onto the end of TimeW in Table6, the data from Table7 will appear after the data from Table6.

August 11, 2013 at 09:15 pm - Permalink