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Count features in geodatabase

MihaKlemencic

I am new to python and I would to like to count the number of features in each feature class that meet certain criteria.

In geodatabase I have many feature classes. One of the attribute field has values "number/number" --> 50/2, 99/6

I would to like to loop each feature class, select layer by attribute and count selected features, which contain sign "/" and print the result. Below is python code:

<SPAN class="keyword token">import</SPAN> arcpy

<SPAN class="comment token">#Set the input workspace</SPAN>
arcpy<SPAN class="punctuation token">.</SPAN>env<SPAN class="punctuation token">.</SPAN>workspace <SPAN class="operator token">=</SPAN> <SPAN class="string token">"d:/TMP/miha_k/zirovnica/novo/test.gdb"</SPAN>

fcs <SPAN class="operator token">=</SPAN> arcpy<SPAN class="punctuation token">.</SPAN>ListFeatureClasses<SPAN class="punctuation token">(</SPAN><SPAN class="punctuation token">)</SPAN>
cursor <SPAN class="operator token">=</SPAN> arcpy<SPAN class="punctuation token">.</SPAN>SearchCursor<SPAN class="punctuation token">(</SPAN>fcs<SPAN class="punctuation token">)</SPAN>

<SPAN class="keyword token">for</SPAN> row <SPAN class="keyword token">in</SPAN> fcs<SPAN class="punctuation token">:</SPAN>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; arcpy<SPAN class="punctuation token">.</SPAN>SelectLayerByAttribute_management<SPAN class="punctuation token">(</SPAN>fcs<SPAN class="punctuation token">,</SPAN> <SPAN class="string token">"NEW_SELECTION"</SPAN><SPAN class="punctuation token">,</SPAN> <SPAN class="string token">"PARCELA LIKE '%/%'"</SPAN><SPAN class="punctuation token">)</SPAN>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; arcpy<SPAN class="punctuation token">.</SPAN>GetCount_management<SPAN class="punctuation token">(</SPAN>fcs<SPAN class="punctuation token">)</SPAN>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <SPAN class="keyword token">print</SPAN> row‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍<SPAN class="line-numbers-rows"><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN></SPAN>

I would appreciate your help

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Accepted answers

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MaxMarno

Agreed, in considering processing time, your version would be quicker and more reliable. However like you noted as well for a smaller dataset the difference would be negligible. Cheers to SQL!

DarrenWiens2

Technically, this works. I'm not always the one to do things the "right" way either, but there are a few reasons not to do it this way:

- you need to manually count the field index

- this method reads every feature in the feature class. Using a where clause only reads the matching features, through the magic of SQL, which I don't understand, but from the help, "When a query is specified for an update or search cursor, only the records satisfying that query are returned." Anyhow, it seems to take about 3x longer to read through everything, but it likely depends on the data and how many matches there are. Also, to be fair, the results below are representative of several runs, except the first run, which adds about 3s in actually constructing the table view. So, I suppose the main point is that this method is just fine for small data sets, but likely worse for large data sets.

import timeit
fc = 'bc_geoname_albers' # ~45,000 features

# SQL method
start_time = timeit.default_timer()
arcpy.MakeTableView_management(fc, "myTableView", "CGNDBKEY LIKE '%C%'")
Count = int(arcpy.GetCount_management("myTableView").getOutput(0))
print (Count,str(timeit.default_timer() - start_time))

# Count method
start_time = timeit.default_timer()
with arcpy.da.SearchCursor(fc, "*") as cursor:
&nbsp;&nbsp;&nbsp; Count = 0
&nbsp;&nbsp;&nbsp; for row in cursor:
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; if "C" in str(row[4]):
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Count+=1
print (Count,timeit.default_timer() - start_time)

(13531, 0.64809157931) # SQL method: 0.65s
(13531, 1.87391371297) # Count method: 1.87s‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍<SPAN class="line-numbers-rows"><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN></SPAN>

MaxMarno

Try the following function (first substituting the field index number for '10' for your search field.

<SPAN class="keyword token">def</SPAN> <SPAN class="token function">countfeaturesfun</SPAN><SPAN class="punctuation token">(</SPAN>inFC<SPAN class="punctuation token">)</SPAN><SPAN class="punctuation token">:</SPAN>
&nbsp;&nbsp;&nbsp; <SPAN class="keyword token">with</SPAN> arcpy<SPAN class="punctuation token">.</SPAN>da<SPAN class="punctuation token">.</SPAN>SearchCursor<SPAN class="punctuation token">(</SPAN>inFC<SPAN class="punctuation token">,</SPAN> <SPAN class="string token">"*"</SPAN><SPAN class="punctuation token">)</SPAN> <SPAN class="keyword token">as</SPAN> cursor<SPAN class="punctuation token">:</SPAN>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Count <SPAN class="operator token">=</SPAN> <SPAN class="number token">0</SPAN>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <SPAN class="keyword token">for</SPAN> row <SPAN class="keyword token">in</SPAN> cursor<SPAN class="punctuation token">:</SPAN>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <SPAN class="keyword token">if</SPAN> <SPAN class="string token">"/"</SPAN> <SPAN class="keyword token">in</SPAN> str<SPAN class="punctuation token">(</SPAN>row<SPAN class="punctuation token">[</SPAN><SPAN class="number token">10</SPAN><SPAN class="punctuation token">]</SPAN><SPAN class="punctuation token">)</SPAN><SPAN class="punctuation token">:</SPAN>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Count<SPAN class="operator token">+=</SPAN><SPAN class="number token">1</SPAN>
&nbsp;&nbsp;&nbsp; <SPAN class="keyword token">return</SPAN> Count<SPAN class="line-numbers-rows"><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN></SPAN>

RandyBurton

1. Follow Dan Patterson‌'s Py... blog.

2. Check out Some Python Snippets

3. Free online courses like Tutorials Point

RebeccaStrauch__GISP

There are quite a few threads in the forum for learning Python. Do a quick search and you can find them. Here is a start

MihaKlemencic

Thanks for help

Really need to learn python for ArcGIS. Can you suggest any of books?

JoshuaBixby

FIDSet is a Layer property, calling it will generate an attribute error if Describe is passed a feature class directly. If a table view or feature layer is passed to Describe, then FIDSet should return a value, but I think rvburton‌ approach obviates the need for checking FIDSet.

DarrenWiens2

Just to add that you can test whether or not there is a selection by inspecting the describe FIDSet property:

<SPAN class="punctuation token">.</SPAN><SPAN class="punctuation token">.</SPAN><SPAN class="punctuation token">.</SPAN> <SPAN class="keyword token">if</SPAN> arcpy<SPAN class="punctuation token">.</SPAN>Describe<SPAN class="punctuation token">(</SPAN>fc<SPAN class="punctuation token">)</SPAN><SPAN class="punctuation token">.</SPAN>FIDSet <SPAN class="operator token">==</SPAN> <SPAN class="string token">''</SPAN><SPAN class="punctuation token">:</SPAN>
<SPAN class="punctuation token">.</SPAN><SPAN class="punctuation token">.</SPAN><SPAN class="punctuation token">.</SPAN>&nbsp;&nbsp;&nbsp;&nbsp; <SPAN class="keyword token">print</SPAN> <SPAN class="string token">'There is no selection'</SPAN>
<SPAN class="punctuation token">.</SPAN><SPAN class="punctuation token">.</SPAN><SPAN class="punctuation token">.</SPAN> <SPAN class="keyword token">else</SPAN><SPAN class="punctuation token">:</SPAN>
<SPAN class="punctuation token">.</SPAN><SPAN class="punctuation token">.</SPAN><SPAN class="punctuation token">.</SPAN>&nbsp;&nbsp;&nbsp;&nbsp; <SPAN class="keyword token">print</SPAN> <SPAN class="string token">'There is a selection'</SPAN><SPAN class="line-numbers-rows"><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN></SPAN>

RandyBurton

To loop through all the features, you might try the following code. However, if the where clause fails, you may get a count of all records.

<SPAN class="keyword token">import</SPAN> arcpy

arcpy<SPAN class="punctuation token">.</SPAN>env<SPAN class="punctuation token">.</SPAN>workspace <SPAN class="operator token">=</SPAN> r<SPAN class="string token">"d:/TMP/miha_k/zirovnica/novo/test.gdb"</SPAN>

fcs <SPAN class="operator token">=</SPAN> arcpy<SPAN class="punctuation token">.</SPAN>ListFeatureClasses<SPAN class="punctuation token">(</SPAN><SPAN class="punctuation token">)</SPAN>

<SPAN class="keyword token">for</SPAN> row <SPAN class="keyword token">in</SPAN> fcs<SPAN class="punctuation token">:</SPAN>
&nbsp;&nbsp;&nbsp; arcpy<SPAN class="punctuation token">.</SPAN>MakeTableView_management<SPAN class="punctuation token">(</SPAN>row<SPAN class="punctuation token">,</SPAN> <SPAN class="string token">"myTableView"</SPAN><SPAN class="punctuation token">,</SPAN> <SPAN class="string token">"PARCELA LIKE '%/%'"</SPAN><SPAN class="punctuation token">)</SPAN>
&nbsp;&nbsp;&nbsp; <SPAN class="keyword token">print</SPAN> row<SPAN class="punctuation token">,</SPAN> int<SPAN class="punctuation token">(</SPAN>arcpy<SPAN class="punctuation token">.</SPAN>GetCount_management<SPAN class="punctuation token">(</SPAN><SPAN class="string token">"myTableView"</SPAN><SPAN class="punctuation token">)</SPAN><SPAN class="punctuation token">.</SPAN>getOutput<SPAN class="punctuation token">(</SPAN><SPAN class="number token">0</SPAN><SPAN class="punctuation token">)</SPAN><SPAN class="punctuation token">)</SPAN>
&nbsp;&nbsp;&nbsp; arcpy<SPAN class="punctuation token">.</SPAN>Delete_management<SPAN class="punctuation token">(</SPAN><SPAN class="string token">"myTableView"</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>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN></SPAN>

MihaKlemencic

Field "PARCELA" exits in all tables.

The workflow is:

select by attributes
write query "PARCELA LIKE '%/%'"
Count selected features

But doing this workflow manually on more than 100 feature classes is time consuming.

RandyBurton

As Darren suggested, I don't think you would want to cycle through all your features; they might not have the fields you want to query anyway.

Here's some code based on this link:

arcpy<SPAN class="punctuation token">.</SPAN>env<SPAN class="punctuation token">.</SPAN>workspace <SPAN class="operator token">=</SPAN> r<SPAN class="string token">"d:/TMP/miha_k/zirovnica/novo/test.gdb"</SPAN>
in_table <SPAN class="operator token">=</SPAN> <SPAN class="string token">"featureToSearch"</SPAN>

<SPAN class="comment token"># MakeTableView_management (in_table, out_view, {where_clause}, {workspace}, {field_info})</SPAN>
arcpy<SPAN class="punctuation token">.</SPAN>MakeTableView_management<SPAN class="punctuation token">(</SPAN>in_table<SPAN class="punctuation token">,</SPAN> <SPAN class="string token">"myTableView"</SPAN><SPAN class="punctuation token">,</SPAN> <SPAN class="string token">"PARCELA LIKE '%/%'"</SPAN><SPAN class="punctuation token">)</SPAN>
count <SPAN class="operator token">=</SPAN> int<SPAN class="punctuation token">(</SPAN>arcpy<SPAN class="punctuation token">.</SPAN>GetCount_management<SPAN class="punctuation token">(</SPAN><SPAN class="string token">"myTableView"</SPAN><SPAN class="punctuation token">)</SPAN><SPAN class="punctuation token">.</SPAN>getOutput<SPAN class="punctuation token">(</SPAN><SPAN class="number token">0</SPAN><SPAN class="punctuation token">)</SPAN><SPAN class="punctuation token">)</SPAN>‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍<SPAN class="line-numbers-rows"><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN></SPAN>

But, if your features all contain the same field in your where query, you could do a "for row in fcs" loop. You could also add an if "feature in list" line to limit the features used.

DarrenWiens2

A few things:

- Cursors cycle through individual features within a feature class/table. You don't seem to need that here.

- When you do 'for row in fcs:', the individual feature class is called row. The list of feature classes is fcs. So, you should select from row, not fcs.

- Refer to the help for GetCount, especially the example. Note that it returns a result, not a number.

DanPatterson_Retired

taking a wild guess that you got an error... what was it? what field are you querying in each table? is there any similarity between the tables? Have you done this manually? can you put your workflow into a model?

Just some ideas to get you started

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