[GRASS-user] r.out.ascii not functioning for floating point values

Sat Jan 21 00:26:49 PST 2017

Hi Chris
(now it's morning here :-)

I never had occasion to use the -m option to r.out.ascii. I guess that 
since MODFLOW is a fortran program, and fortran uses scientific 
notation, that's why the -m flag produces that scientific notation.

But I was curious, so I tired to recreate your steps. Here's what I did:
Downloaded the netcdf temp data from
https://www.esrl.noaa.gov/psd/data/gridded/data.UDel_AirT_Precip.html

I got just the Apr 2014 slice with:
ncks -d time,1369,1369 air.mon.mean.v401.nc air_april2014.nc

GRASS can read in netcdf, so in a Lon/Lat Location I ran:
r.in.gdal -l -o input=air_april2014.nc output=air_apr14

Next I set the computational region to 0.25 degrees:
g.region -p rast=air_apr14 res=0:15

And I create a new raster at that resolution:
r.mapcalc "air_apr14_25 = air_apr14"

I can now export to an ascii file, as you did, which gives the rows and 
cols as you showed.
Although it's not clear yet what you need excel for? I want to believe 
that whatever your needs are, it can be done right in GIS.

Regards,
Micha

On 01/21/2017 02:15 AM, Bartolomei.Chris wrote:
> I think I found one of my problems working with the data and why it was lining up ... in Excel, if you use a space delimiter, the text-to-columns treats consecutive spaces as one ... you need to disable that (a checkbox).  That still doesn't fix the scientific notation issue, but the process I'm using now seems to work.
>
>
> :)
>
> Chris
>
> ________________________________
> From: Bartolomei.Chris
> Sent: Friday, January 20, 2017 10:39 AM
> To: Micha Silver; grass-user
> Subject: Re: [GRASS-user] r.out.ascii not functioning for floating point values
>
>
> Good (morning?) Micha  :)
>
> r.out.ascii dumps the values, not the x,y locations - that is r.out.xyz ... and r.out.ascii is indeed generating the scientific notation - I've pulled the output file up in Notepad++ to view the raw data and here's what I see for rows with data values (a snippet):
>
> -4.9e+001-4.9e+001-5.0e+001-5.0e+001-4.9e+001-4.9e+001-5.0e+001-5.0e+001
>
> and here's what I see for rows with no data (also a snippet):
>
> 0.0e+0000.0e+0000.0e+0000.0e+0000.0e+0000.0e+0000.0e+0000.0e+0000.0e+0000.0e+000
>
> Note that 1) there is no way to turn scientific notation off (these are mean monthly temperatures so the values are <100 and 2 decimal places) and 2) there is nothing separating the values generated 3) This does not happen if the values are integers
>
> Testing this morning:
>
> If I do not use the MODFLOW checkbox, then this is what I get for no data rows:
>
> * * * * * * * * * * * * * * * * * * * * * *
>
> and this is what I get for rows with values:
>
> -42.3 -42.3 -41.2 -41.2 -43.5 -43.5
>
> but the number of values in each row vary from .... awww man .... wtf?  I just reran this without the MODFLOW check box and now the data all lines up correctly ... that is weird (but good news!)
>
> stay tuned - I'll repost more if this messes up again. My guess is that the module remembered a setting of something from the numerous times I tried different values.  When in doubt, reboot, right?
>
> Here's what I just ran in case anyone else needs the settings:
>
> r.out.ascii -h --overwrite input=AirTemp_Test2 at Zoonotic output=D:\air_temp_2014\Test3 precision=3 (note I did not set the width value here)
> Wow - that was really really strange. Well - I'm not going to kick good news around - the issue with MODFLOW and floating point values should still be looked at though. I reran the MODFLOW option this morning as well and I get the same results as described above.
>
> Chris
>
>
> Chris Bartolomei P.E.
> bartolomei.chris at ensco.com
>
>
> ________________________________
> From: Micha Silver<tsvibar at gmail.com>
> Sent: Friday, January 20, 2017 9:52 AM
> To: Bartolomei.Chris; grass-user
> Subject: Re: [GRASS-user] r.out.ascii not functioning for floating point values
>
>
> Hello Chris
>
> What is it that you're trying to do in Excel?? Chances are that you can do any analysis you want right in the GIS.
>
> The scientific notation is surely from Excel, r.out.ascii just dumps a list of three numbers: x,y, and raster values. All in straight ascii.
>
>
> On 01/20/2017 01:24 PM, Bartolomei.Chris wrote:
>
> I am using GRASS GIS 7.2 on a Windows 10 system with 32Gb ram. OSGEO4W distribution (with msys)
>
> The region is lat/lon (-180 to 180, 90 to -90) and the resolution NS is 00:15 and EW is 00:15
>
> I am trying to export a raster into a grid (array) that I can use in Excel but am getting unusable output ... Here's what I do:
>
> I create a text file in Excel with the data (University of Delaware - Global Monthly Mean Temperatures, 2014, using April) and add the header rows:
>
> ncols 720
> nrows 360
> xllcorner -180
> yllcorner -90
> cellsize .50
> nodata_value -99999
> each cell has some value in it, if it isn't "-99999" then it is a floating point number (signed, 2 decimal places)
>
> I save it as a space-sparated text file with a .asc extension
>
> I import the raster using r.in.arc (r.in.arc input=AirTemp_Test2.asc output=AirTemp_Test2 type=FCELL --overwrite) which imports fine.
>
> My region is set as described above and now I want to resample on the fly and export an ASCII grid I can use in Excel so I want new each row of data to have 1440 columns (since the new resolution is 2x the original)
>
> I have tried r.out.ascii (r.out.ascii -h -m input=AirTemp_Test2 output=D:\air_temp_2014\Test2.txt precision=2 width=1440 --overwrite) but the problem I have is that it is floating point values and for some reason all of the data exported into the ASCII grid is in scientific notation with no separation between the values. In order to get an even 1440 x 720 ASCII grid, I need to check the "Write MODFLOW (USGS) ASCII array" box in the GUI and set the number of significant digits to 2 (otherwise you just get integers) and the wrapping number to 1440 ... this works fine for integers but defaults to the scientific notation for floating point which since there are no value separators, can't be worked with (integers are separated by a space). Two things: can we turn off scientific notation?, and add a separator for floating point values ... (please)
>
> If I do not check the MODFLOW box, the grid output has the appropriate number of rows (720) but many of them have their data truncated. Every row should have 1440 values.
>
> I have tried r.out.arc (r.out.arc input=AirTemp_Test2 output=AirTest2 dp=2 --overwrite) as well and while it generates the grid with space-separated values, they also seem to be truncated ... the truncation is not consistent either...
>
> Am I doing something really wrong here ???
>
> Thanks :)
>
>
> Chris Bartolomei P.E.
> bartolomei.chris at ensco.com<mailto:bartolomei.chris at ensco.com>
>
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