topic Re: Export values of rasters without attribute table in Geoprocessing Questions

Export values of rasters without attribute table

CamiSunley — Sat, 28 Nov 2020 12:35:52 GMT

Hello, everyone !

I have a file with multiple rasters (stretched - without attribute table - but with only one value e.g. min value = max value) and I am trying to export each raster's value in a table/xls file where the values from all the rasters will have been registered (in a column for example) using model builder or arcpy.

Any suggestion is welcomed, thank you !

Re: Export values of rasters without attribute table

DavidPike — Sat, 28 Nov 2020 13:01:25 GMT

How many rasters have you got? You're saying each raster is made of cells entirely of one value?

Can you post a picture of this?

raster_object = arcpy.Raster(r'C:\MyStuff\Geo\Raster1.tif) min_value = raster_object.minimum max_value = raster_object.maximum

Re: Export values of rasters without attribute table

CamiSunley — Sat, 28 Nov 2020 13:11:49 GMT

I have 1176 rasters. Yes, each raster is made of cells entirely of one value.

Re: Export values of rasters without attribute table

DavidPike — Sat, 28 Nov 2020 13:16:19 GMT

try the above script on one of the rasters. If that works, it can easily be put into a for loop to iterate over the 1000. Unsure if it's the fastest way if you're looking to do this regularly? Maybe @DanPatterson has a numpy method.

Re: Export values of rasters without attribute table

CamiSunley — Sat, 28 Nov 2020 13:27:05 GMT

Thank you, I' ll try it.. Should I add an 'export' expression after your script so as to save the value in a new table/array ?

Re: Export values of rasters without attribute table

DavidPike — Sat, 28 Nov 2020 13:30:56 GMT

for the moment just use

print(min_value)

Re: Export values of rasters without attribute table

Amadeus111 — Sat, 28 Nov 2020 16:34:54 GMT

You can read min values from the each raster and add to a list, then write into an excel file. You might need to download xlswriter library or write into .dbf file and convert to excel file. There are multiple ways writing from list to excel file

import arcpy
import os
import xlsxwriter

raster_list = os.listdir(path/to/rasterfolder)
value_list = []

for each_raster in raster_list:
    result = arcpy.GetRasterProperties_management(each_raster, "MINIMUM")
    min_value = result.getOutput(0)
    value_list.add(min_value)

with xlsxwriter.Workbook('RasterValues.xlsx') as workbook:
    worksheet = workbook.add_worksheet()

    for row_num, data in enumerate(value_list):
        worksheet.write_row(row_num, 0, data)

Re: Export values of rasters without attribute table

DanPatterson — Sat, 28 Nov 2020 16:41:46 GMT

import arcpy import numpy as np arcpy.env.workspace = "c:/data/DEMS" # --- Set the current workspace rasters = arcpy.ListRasters("*") out = [] for raster in rasters: inRas = arcpy.Raster(raster) arr = arcpy.RasterToNumPyArray(inRas) ras_min = np.min(arr) out.append([raster, ras_min]) print(out) # ---- for now, just print it or see # NumPyArrayToTable

Now, if you have nodata values to account for, then the code will have to be edited, or if the rasters are all over the place, then good luck.

This should give you an idea... but I never tested it, just cobbled together from the help files

NumPyArrayToTable—ArcGIS Pro | Documentation

Re: Export values of rasters without attribute table

CamiSunley — Sat, 28 Nov 2020 21:05:47 GMT

Thank you, I tried to install xlsxwrite with several ways but "invalid syntax" message is always appeared..

Re: Export values of rasters without attribute table

CamiSunley — Sat, 28 Nov 2020 21:14:19 GMT

Thank you, I replaced 'min' with 'max' and it returned the right values, because when I run it for 'min' it returned numbers tending to zero.