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Loop: Select by attribute and write to attribute table

jadenrowley

Is there a way to loop this function so that I'm not retyping it each time? I want to select and write to the attribute table for 3 bands, but am lost on how to loop this. See code below:

import arcpy

arcpy.SelectLayerByAttribute_management("Strain Regions","NEW_SELECTION",'''"band_number" = 'Band 1' ''')
arcpy.SelectLayerByLocation_management("Earthquakes","COMPLETELY_WITHIN","Strain Regions",'',"ADD_TO_SELECTION")
arcpy.AddField_management("Earthquakes",'region2', "TEXT")
arcpy.CalculateField_management("Earthquakes","region2",'"band 1"')
arcpy.SelectLayerByAttribute_management("Strain Regions","CLEAR_SELECTION")
arcpy.SelectLayerByAttribute_management("Earthquakes","CLEAR_SELECTION")

arcpy.SelectLayerByAttribute_management("Strain Regions","NEW_SELECTION",'''"band_number" = 'Band 2' ''')
arcpy.SelectLayerByLocation_management("Earthquakes","COMPLETELY_WITHIN","Strain Regions",'',"ADD_TO_SELECTION")
arcpy.AddField_management("Earthquakes",'region2', "TEXT")
arcpy.CalculateField_management("Earthquakes","region2",'"band 2"')
arcpy.SelectLayerByAttribute_management("Strain Regions","CLEAR_SELECTION")
arcpy.SelectLayerByAttribute_management("Earthquakes","CLEAR_SELECTION")

arcpy.SelectLayerByAttribute_management("Strain Regions","NEW_SELECTION",'''"band_number" = 'Band 3' ''')
arcpy.SelectLayerByLocation_management("Earthquakes","COMPLETELY_WITHIN","Strain Regions",'',"ADD_TO_SELECTION")
arcpy.AddField_management("Earthquakes",'region2', "TEXT")
arcpy.CalculateField_management("Earthquakes","region2",'"band 3"')
arcpy.SelectLayerByAttribute_management("Strain Regions","CLEAR_SELECTION")
arcpy.SelectLayerByAttribute_management("Earthquakes","CLEAR_SELECTION")

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Accepted answers

DarrenWiens2

Untested, but I think it should be like this:

<SPAN class="keyword token">for</SPAN> i <SPAN class="keyword token">in</SPAN> range<SPAN class="punctuation token">(</SPAN><SPAN class="number token">1</SPAN><SPAN class="punctuation token">,</SPAN><SPAN class="number token">4</SPAN><SPAN class="punctuation token">)</SPAN><SPAN class="punctuation token">:</SPAN> <SPAN class="comment token"># returns 1,2,3</SPAN>
&nbsp;&nbsp;&nbsp; arcpy<SPAN class="punctuation token">.</SPAN>SelectLayerByAttribute_management<SPAN class="punctuation token">(</SPAN><SPAN class="string token">"Strain Regions"</SPAN><SPAN class="punctuation token">,</SPAN><SPAN class="string token">"NEW_SELECTION"</SPAN><SPAN class="punctuation token">,</SPAN><SPAN class="string token">'''"band_number" = 'Band ' + str(i) '''</SPAN><SPAN class="punctuation token">)</SPAN>
&nbsp;&nbsp;&nbsp; arcpy<SPAN class="punctuation token">.</SPAN>SelectLayerByLocation_management<SPAN class="punctuation token">(</SPAN><SPAN class="string token">"Earthquakes"</SPAN><SPAN class="punctuation token">,</SPAN><SPAN class="string token">"COMPLETELY_WITHIN"</SPAN><SPAN class="punctuation token">,</SPAN><SPAN class="string token">"Strain Regions"</SPAN><SPAN class="punctuation token">,</SPAN><SPAN class="string token">''</SPAN><SPAN class="punctuation token">,</SPAN><SPAN class="string token">"ADD_TO_SELECTION"</SPAN><SPAN class="punctuation token">)</SPAN>
&nbsp;&nbsp;&nbsp; arcpy<SPAN class="punctuation token">.</SPAN>AddField_management<SPAN class="punctuation token">(</SPAN><SPAN class="string token">"Earthquakes"</SPAN><SPAN class="punctuation token">,</SPAN><SPAN class="string token">'region2'</SPAN><SPAN class="punctuation token">,</SPAN> <SPAN class="string token">"TEXT"</SPAN><SPAN class="punctuation token">)</SPAN>
&nbsp;&nbsp;&nbsp; arcpy<SPAN class="punctuation token">.</SPAN>CalculateField_management<SPAN class="punctuation token">(</SPAN><SPAN class="string token">"Earthquakes"</SPAN><SPAN class="punctuation token">,</SPAN><SPAN class="string token">"region2"</SPAN><SPAN class="punctuation token">,</SPAN><SPAN class="string token">'"band " + str(i) '</SPAN><SPAN class="punctuation token">)</SPAN>
&nbsp;&nbsp;&nbsp; arcpy<SPAN class="punctuation token">.</SPAN>SelectLayerByAttribute_management<SPAN class="punctuation token">(</SPAN><SPAN class="string token">"Strain Regions"</SPAN><SPAN class="punctuation token">,</SPAN><SPAN class="string token">"CLEAR_SELECTION"</SPAN><SPAN class="punctuation token">)</SPAN>
&nbsp;&nbsp;&nbsp; arcpy<SPAN class="punctuation token">.</SPAN>SelectLayerByAttribute_management<SPAN class="punctuation token">(</SPAN><SPAN class="string token">"Earthquakes"</SPAN><SPAN class="punctuation token">,</SPAN><SPAN class="string token">"CLEAR_SELECTION"</SPAN><SPAN class="punctuation token">)</SPAN><SPAN class="line-numbers-rows"><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN></SPAN>

Basically, by using str(i) in the loop, it changes from 1 to 2 to 3.

All comments

jadenrowley

This helps- I've rarely used field delimiters being new to arcpy so I'll do some reading.

DarrenWiens2

Yes, I assume it does have to do with the quotes. It looks like a mess, but here's how I try to set up my queries.

1.) Enclose the main query in triple-double-quotes.

2.) Use 'format' notation.

3.) Use AddFieldDelimiters to avoid the quote/bracket/nothing problem between data sources.

arcpy<SPAN class="punctuation token">.</SPAN>SelectLayerByAttribute_management<SPAN class="punctuation token">(</SPAN><SPAN class="string token">"Strain Regions"</SPAN><SPAN class="punctuation token">,</SPAN><SPAN class="string token">"NEW_SELECTION"</SPAN><SPAN class="punctuation token">,</SPAN><SPAN class="string token">""" {} = 'Band {}' """</SPAN><SPAN class="punctuation token">.</SPAN>format<SPAN class="punctuation token">(</SPAN>arcpy<SPAN class="punctuation token">.</SPAN>AddFieldDelimiters<SPAN class="punctuation token">(</SPAN><SPAN class="string token">"Strain Regions"</SPAN><SPAN class="punctuation token">,</SPAN><SPAN class="string token">"band_number"</SPAN><SPAN class="punctuation token">)</SPAN><SPAN class="punctuation token">,</SPAN>str<SPAN class="punctuation token">(</SPAN>i<SPAN class="punctuation token">)</SPAN><SPAN class="punctuation token">)</SPAN><SPAN class="punctuation token">)</SPAN>‍

More info and an example here.

jadenrowley

Thank you! I'm still getting an issue as follows:

An invalid SQL statement was used. [SELECT OBJECTID FROM polygons WHERE "band_number" = 'Band ' + str(i) ]

I'm guessing it's an error with quotation marks or spacing of some sort, so I'm trying to change it around here.

DarrenWiens2

Untested, but I think it should be like this:

<SPAN class="keyword token">for</SPAN> i <SPAN class="keyword token">in</SPAN> range<SPAN class="punctuation token">(</SPAN><SPAN class="number token">1</SPAN><SPAN class="punctuation token">,</SPAN><SPAN class="number token">4</SPAN><SPAN class="punctuation token">)</SPAN><SPAN class="punctuation token">:</SPAN> <SPAN class="comment token"># returns 1,2,3</SPAN>
&nbsp;&nbsp;&nbsp; arcpy<SPAN class="punctuation token">.</SPAN>SelectLayerByAttribute_management<SPAN class="punctuation token">(</SPAN><SPAN class="string token">"Strain Regions"</SPAN><SPAN class="punctuation token">,</SPAN><SPAN class="string token">"NEW_SELECTION"</SPAN><SPAN class="punctuation token">,</SPAN><SPAN class="string token">'''"band_number" = 'Band ' + str(i) '''</SPAN><SPAN class="punctuation token">)</SPAN>
&nbsp;&nbsp;&nbsp; arcpy<SPAN class="punctuation token">.</SPAN>SelectLayerByLocation_management<SPAN class="punctuation token">(</SPAN><SPAN class="string token">"Earthquakes"</SPAN><SPAN class="punctuation token">,</SPAN><SPAN class="string token">"COMPLETELY_WITHIN"</SPAN><SPAN class="punctuation token">,</SPAN><SPAN class="string token">"Strain Regions"</SPAN><SPAN class="punctuation token">,</SPAN><SPAN class="string token">''</SPAN><SPAN class="punctuation token">,</SPAN><SPAN class="string token">"ADD_TO_SELECTION"</SPAN><SPAN class="punctuation token">)</SPAN>
&nbsp;&nbsp;&nbsp; arcpy<SPAN class="punctuation token">.</SPAN>AddField_management<SPAN class="punctuation token">(</SPAN><SPAN class="string token">"Earthquakes"</SPAN><SPAN class="punctuation token">,</SPAN><SPAN class="string token">'region2'</SPAN><SPAN class="punctuation token">,</SPAN> <SPAN class="string token">"TEXT"</SPAN><SPAN class="punctuation token">)</SPAN>
&nbsp;&nbsp;&nbsp; arcpy<SPAN class="punctuation token">.</SPAN>CalculateField_management<SPAN class="punctuation token">(</SPAN><SPAN class="string token">"Earthquakes"</SPAN><SPAN class="punctuation token">,</SPAN><SPAN class="string token">"region2"</SPAN><SPAN class="punctuation token">,</SPAN><SPAN class="string token">'"band " + str(i) '</SPAN><SPAN class="punctuation token">)</SPAN>
&nbsp;&nbsp;&nbsp; arcpy<SPAN class="punctuation token">.</SPAN>SelectLayerByAttribute_management<SPAN class="punctuation token">(</SPAN><SPAN class="string token">"Strain Regions"</SPAN><SPAN class="punctuation token">,</SPAN><SPAN class="string token">"CLEAR_SELECTION"</SPAN><SPAN class="punctuation token">)</SPAN>
&nbsp;&nbsp;&nbsp; arcpy<SPAN class="punctuation token">.</SPAN>SelectLayerByAttribute_management<SPAN class="punctuation token">(</SPAN><SPAN class="string token">"Earthquakes"</SPAN><SPAN class="punctuation token">,</SPAN><SPAN class="string token">"CLEAR_SELECTION"</SPAN><SPAN class="punctuation token">)</SPAN><SPAN class="line-numbers-rows"><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN></SPAN>

Basically, by using str(i) in the loop, it changes from 1 to 2 to 3.

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