How to fix ascii to raster error

884
8
10-10-2019 01:55 AM
GerardSummers
New Contributor

I am trying to create a raster from an ascii text file in python through the arcpy tool ASCIIToRaster_conversion(). I have the ascii text formatted as so:

NCOL 39
NROWS 54
XLLCORNER 2760.091202
YLLCORNER -1253.840905
CELLSIZE 2.0
NODATA_VALUE -99999
5.789899100000000232e+01 2.760091202000000067e+03 -1.253840905000000021e+03
6.423454300000000217e+01 2.762091202000000067e+03 -1.253840905000000021e+03

I have created the raster file through make x y event layer and the details all match up bar the nodata value, which is left blank. 

The code used to create the ascii is:

xmin = np.min(myArray[:,1])
ymin = np.min(myArray[:,2])

cell_size = "2"

col = np.max(myArray[:,1]) - xmin
row = np.max(myArray[:,2]) - np.min(myArray[:,2])

header = "NCOL " + str(col) + "\n".format(myArray.shape[1])
header += "NROWS " + str(row) + "\n".format(myArray.shape[0])
header += "XLLCORNER " + str(xmin)+ "\n"
header += "YLLCORNER " + str(ymin)+ "\n"
header += "CELLSIZE " + str(cell_size) + "\n"
header += "NODATA_VALUE -99999"

np.savetxt("myGrid.asc", myArray, delimiter = " ",header = header, comments="")

The code used to open the ascii text and put it through the raster converter is:

Workspace= "D:/Documents/PhD/GIS/Odhran"

arcpy.ASCIIToRaster_conversion("mygrid.asc", Workspace, "INTEGER")

The associated error message is:

Traceback (most recent call last):
File "C:\Python27\ArcGIS10.6\Lib\site-packages\pythonwin\pywin\framework\scriptutils.py", line 326, in RunScript
exec codeObject in __main__.__dict__
File "D:\Documents\Csv_to_raster_sub.py", line 12, in <module>
Workspace, "INTEGER")
File "C:\Program Files (x86)\ArcGIS\Desktop10.6\ArcPy\arcpy\conversion.py", line 2461, in ASCIIToRaster
raise e
ExecuteError: ERROR 010158: Unable to open file MYGRID.ASC.
ERROR 010067: Error in executing grid expression.
Failed to execute (ASCIIToRaster).

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8 Replies
NeilAyres
MVP Frequent Contributor

Sorry, but why are you specifying INTEGER when the data is floats

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GerardSummers
New Contributor

Sorry that was a typo the actual code has float specified

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NeilAyres
MVP Frequent Contributor

Ascii to raster will only deal with a one dimensional array I think.

Your myArray appears to have several dimensions. What is the shape of myArray?

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GerardSummers
New Contributor
This is what it looks like when you print it:
[[   57.898991  2760.091202 -1253.840905]  [   64.234543  2762.091202 -1253.840905]  [   58.50209   2764.091202 -1253.840905]  ...  [  206.286987  2832.091202 -1147.840905]  [  181.628342  2834.091202 -1147.840905]  [  154.994568  2836.091202 -1147.840905]]
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NeilAyres
MVP Frequent Contributor

That looks like a "3 band" dataset.

I think that you will only be able to make a raster using AsciiToRaster using 1 band at a time.

So create a *.asc using list position 0, then 1 etc

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GerardSummers
New Contributor

This is what it looks like when you print it:

[[   57.898991  2760.091202 -1253.840905]  [   64.234543  2762.091202 -1253.840905]  [   58.50209   2764.091202 -1253.840905]  ...  [  206.286987  2832.091202 -1147.840905]  [  181.628342  2834.091202 -1147.840905]  [  154.994568  2836.091202 -1147.840905]]
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SteveLynch
Esri Regular Contributor

- you are sending the output to an Esri grid named "D:/Documents/PhD/GIS/Odhran", correct?

- specify the full path to mygrid.asc

- these ASCII files are actually raster datasets and you could use CopyRaster ipo ASCIIToRaster

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DuncanHornby
MVP Frequent Contributor

It may be failing because you are expressing the number using notation? Try make your numbers without this, have a look here.

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