topic Re: Im Trying to use a loop to create seperate buffers for each row from attribute va in Python Questions

Im Trying to use a loop to create seperate buffers for each row from attribute values

OLANIYANOLAKUNLE — Sat, 08 Sep 2012 22:30:59 GMT

Im Trying to use a loop to create seperate buffers for each of the row from attribute values of a field in a feature using searchcursor, but its not working the code i used is below;

mxd = arcpy.mapping.MapDocument("Current") df = arcpy.mapping.ListDataFrames(mxd)[0] fc = "Parcels" field = "Plot_No" cursor = arcpy.SearchCursor(fc) for row in cursor:     val = row.getValue(field) for val in fc:     outFC = str(val) + "_Buffer" + ".shp"     arcpy.Buffer_analysis(str(val),outFC,"15 meters","FULL","ROUND","NONE")

The error message

Runtime error  Traceback (most recent call last):   File "<string>", line 3, in <module>   File "C:\Program Files (x86)\ArcGIS\Desktop10.1\arcpy\arcpy\analysis.py", line 687, in Buffer     raise e ExecuteError: Failed to execute. Parameters are not valid. ERROR 000732: Input Features: Dataset K does not exist or is not supported Failed to execute (Buffer).

Please what im i doing wrong? Thanks

Re: Im Trying to use a loop to create seperate buffers for each row from attribute va

FabianBlau — Sat, 11 Dec 2021 09:08:11 GMT

I guess you missunderstood the for-loop.
The second loop is outside the first.
You overwrite the val-variable in the loop.
fc holds only the name of the featureclass. Its a string/text.
for val in fc gives you the characters of the fc-name.
Try this (I did not test it):

fc = "Parcels"
field = "Plot_No"
cursor = arcpy.SearchCursor(fc)
for row in cursor:
    feat = row.getValue(shapefieldname) # this gives you the geometry
    val = row.getValue(field) 
    outFC = str(val) + "_Buffer" + ".shp" # there should be no Null-values in "Plot_No", the values have to be unique
    arcpy.Buffer_analysis(feat , outFC, "15 meters", "FULL", "ROUND", "NONE")

Re: Im Trying to use a loop to create seperate buffers for each row from attribute va

markdenil — Mon, 10 Sep 2012 16:32:03 GMT

It may be simpler to run Buffer using your buffer_field
then using a search cursor to compile a list of buffer field values

loop through the list to select and export the buffers with each value
(make Layer then copy features)

That may be simpler than passing each feature individually to Buffer....

Re: Im Trying to use a loop to create seperate buffers for each row from attribute va

OLANIYANOLAKUNLE — Sat, 11 Dec 2021 09:08:13 GMT

Thanks for your response, but after trying the code it returns only 1 feature? and i want it to return a 15meters buffer for all the records

>>> fc = "Parcels"
>>> field = "Plot_No"
>>> shapefieldname = "Shape"
>>> cursor = arcpy.SearchCursor(fc)
>>> for row in cursor:
...     feat = row.getValue(shapefieldname)
...     val = row.getValue(field)
...     outFC = str(val) + "_Buffer" + ".shp"
...     
>>> arcpy.Buffer_analysis(feat , outFC, "15 meters", "FULL", "ROUND", "NONE")
<Result 'C:\\Users\\Administrator\\Documents\\ArcGIS\\8_Buffer.shp'>

What is wrong?

Re: Im Trying to use a loop to create seperate buffers for each row from attribute va

FabianBlau — Tue, 11 Sep 2012 06:14:07 GMT

move the buffer-function into the loop.
The result will be a shapefile for every single row.
If your Plot_No-Field contains non-unique values you should mention marks answer.

Re: Im Trying to use a loop to create seperate buffers for each row from attribute va

OLANIYANOLAKUNLE — Tue, 11 Sep 2012 07:20:24 GMT

move the buffer-function into the loop.
The result will be a shapefile for every single row.
If your Plot_No-Field contains non-unique values you should mention marks answer.

Thanks that did it!

Re: Im Trying to use a loop to create seperate buffers for each row from attribute va

OLANIYANOLAKUNLE — Sat, 11 Dec 2021 09:08:16 GMT

@ fabl and mdenil, thanks for your response...
I want to use the code you suggested to create a list of geoprocessing operations on each of the rows in a feature. I would start with the first row and generate a final pdf output, then move to the next row till the searchcursor is through with all the rows; im thinking along the line of the code you suggested but im not sure if it would take each of the rows one at a time, below is an example of what i want

fc = "Parcels"
field = "Plot_No"
cursor = arcpy.SearchCursor(fc)
for row in cursor:
    feat = row.getValue(shapefieldname) # this gives you the geometry
    val = row.getValue(field) 
    outFC = str(val) + "_Buffer" + ".shp" # there should be no Null-values in "Plot_No", the values have to be unique
    arcpy.Buffer_analysis(feat , outFC, "15 meters", "FULL", "ROUND", "NONE")
    dfAsFeature = arcpy.Polygon(arcpy.Array([df.extent.lowerLeft, df.extent.lowerRight, df.extent.upperRight,     df.extent.upperLeft]),df.spatialReference)
    arcpy.Clip_analysis(lyr,dfAsFeature,outFC) 
    arcpy.mapping.ExportToPDF(mxd,r"C:\KWARA_STATE\\" + outName + "\\" + outName1 + "\\" + "TDP_For_" + outName2) 


fc = "Parcels"
field = "Plot_No"
cursor = arcpy.SearchCursor(fc)
for row in cursor:
    feat = row.getValue(shapefieldname) # this gives you the geometry
    val = row.getValue(field) 
    outFC = str(val) + "_Buffer" + ".shp" # there should be no Null-values in "Plot_No", the values have to be unique
    arcpy.Buffer_analysis(feat , outFC, "15 meters", "FULL", "ROUND", "NONE")
    dfAsFeature = arcpy.Polygon(arcpy.Array([df.extent.lowerLeft, df.extent.lowerRight, df.extent.upperRight,     df.extent.upperLeft]),df.spatialReference)
    arcpy.Clip_analysis(lyr,dfAsFeature,outFC) 
    arcpy.mapping.ExportToPDF(mxd,r"C:\KWARA_STATE\\" + outName + "\\" + outName1 + "\\" + "TDP_For_" + outName2)

Im not particularly sure if i have to repeat each of the geoprocessing operations for each row, the problem is how do i determine the no of rows? the no of rows would not be fix it can change. Your suggestions would be highly appreciated.

Im Trying to use a loop to create Geoprocessing operations for each of the rows

OLANIYANOLAKUNLE — Sun, 16 Sep 2012 06:43:53 GMT

Morning, @ fabl and mdenil im still waiting for any possibility from my last request. Thank you

Re: Im Trying to use a loop to create seperate buffers for each row from attribute va

OLANIYANOLAKUNLE — Thu, 27 Sep 2012 12:56:37 GMT

Thanks i found a solution for my issues

See code Below;

mxd = arcpy.mapping.MapDocument("Current")         df = arcpy.mapping.ListDataFrames(mxd)[0]         fc = 'Database Connections/TDPMode.sde/KWAGISMAIN.DBO.Parcels'         field = "OBJECTID"         field1 = "LGA"         field2 = "District"         field3 = "Block_No"         field4 = "Plot_No"         rows = arcpy.SearchCursor(fc)         row = rows.next()         while row:             val = row.getValue(field)             val1 = row.getValue(field1)             val2 = row.getValue(field2)             val3 = row.getValue(field3)             val4 = row.getValue(field4)             whereClause = '"OBJECTID"' + " = '" + str(val) + "'"             outName = "Block_" + str(val3) + "_Plot_" + str(val4) + "_" + str(val2) + "_Area_of_" + str(val1) + "_LGA" + ".pdf"             path = "C:/Users/Administrator/Documents/ArcGIS/Default.gdb/"             arcpy.SelectLayerByAttribute_management("Parcels", "NEW_SELECTION", whereClause)             arcpy.Buffer_analysis ("Parcels", "DataDrivenPage_Buffer", "14 meters", "FULL", "ROUND", "NONE")             layer_list = "Lines","Parcels","Access_Road_Graphics","Points","Lines_Split"             for layer in layer_list:                 arcpy.SelectLayerByLocation_management(layer, "COMPLETELY_WITHIN", "DataDrivenPage_Buffer", "", "NEW_SELECTION")             exportLayer = "Points", "Lines", "Parcels","Lines_Split","Access_Road_Graphics"             for layer in exportLayer:                 outFC = path + layer + "_New"                  arcpy.Clip_analysis(layer,"DataDrivenPage_Buffer",outFC)                 arcpy.SelectLayerByAttribute_management(layer, "CLEAR_SELECTION")             mxd = arcpy.mapping.MapDocument("current")             lyr = arcpy.mapping.ListLayers(mxd, "Lines_New")[0]             for lblClass in lyr.labelClasses:                 lblClass.SQLQuery = '"ParcelID"' + "=" + str(val)                  arcpy.RefreshActiveView()             arcpy.SelectLayerByAttribute_management("DataDrivenPage_Buffer", "NEW_SELECTION", "OBJECTID = 1")             df.zoomToSelectedFeatures()             mxd = arcpy.mapping.MapDocument("Current")             for df in arcpy.mapping.ListDataFrames(mxd):                 df.rotation = 0             if df.scale <= 400:                  df.scale = 500             if df.scale > 400 and df.scale < 1000:                 df.scale = 1000                 else:                  df.scale = 2000             arcpy.mapping.ExportToPDF(mxd,r"C:\STATE\\Batch\\" + "TDP_For_" + outName)             row = rows.next()

I think i'm improving.....:D