topic Re: Python Script: Create a rectangle using coordinates, width and height atributes from DBF in Python Questions

Python Script: Create a rectangle using coordinates, width and height atributes from DBF

TimGattinger — Wed, 11 Jan 2017 17:01:30 GMT

Dear Xander,

I wonder if it is possible to take width and length of the rectangle from a dbf table.. I have 24 rows with different length and width values, and hence I want to create 24 rectangles with different sizes according to width and length from the dbf table.

Best,

Tim

Re: Python Script: Create a rectangle using coordinates, width and height atributes from DBF

XanderBakker — Wed, 11 Jan 2017 18:33:59 GMT

Question branched from this thread: https://community.esri.com/thread/84853 by xander_bakker‌

Re: Python Script: Create a rectangle using coordinates, width and height atributes from DBF

XanderBakker — Sat, 11 Dec 2021 11:52:00 GMT

Hi Tim Gattinger , I branched your question to a new thread.

Yes it is possible to adapt the script to read width and height attributes from attributes in a DBF. What was not clear to me is if that DBF is a stand alone table or not. In case it is look at the example below.

This will take a DBF (specified on row 7) with the attributes defined on lines 11 to 14 and create a new output featureclass (defined at line 18) that will hold the polygons of the rectangles by reading XY attributes (is this the case?) and the width and height defined in attributes. Important is to specify a relevant (projected) coordinate system on line 21 in which X, Y, width and height are expressed:

import arcpy

def main():
    import os

    # input dbf file, edit this !!!
    tbl = r'D:\Folder\SubFolder\NameOfYour.dbf'

    # edit these field names !!!
    fld_oid_in = 'OID@'
    fld_X = 'X'
    fld_Y = 'Y'
    fld_width = 'Width'
    fld_height = 'Height'
    fld_oid_out = 'OID_DBF'

    # output feature class
    fc_out = r'D:\Folder\SubFolder\NameOfWorkspace.gdb\rectangles' # edit this !!!

    # define a spatial reference, edit this !!!
    sr = arcpy.SpatialReference(3857)  # example for WGS_1984_Web_Mercator_Auxiliary_Sphere

    # create output featureclass
    fc_ws, fc_name = os.path.split(fc_out)
    arcpy.CreateFeatureclass_management(fc_ws, fc_name, "POLYGON", None, None, None, sr)

    # add field OID DBF
    AddField(fc_out, fld_oid_out, "LONG", None)

    # insert cursor to store the results
    flds_out = ('SHAPE@', fld_oid_out)
    with arcpy.da.InsertCursor(fc_out, flds_out) as curs_out:

        # loop over dbf file
        flds = (fld_oid, fld_X, fld_Y, fld_width, fld_height)
        with arcpy.da.SearchCursor(fc, flds) as curs:
            for row in curs:
                oid = row[0]
                x = row[1]
                y = row[2]
                w = row[3]
                h = row[4]
                polygon = createRectangle(x, y, w, h, sr)
                curs_out.insertRow((polygon, oid, ))


def AddField(fc, fld_name, fld_type, fld_length):
    if len(arcpy.ListFields(fc, fld_name)) == 0:
        arcpy.AddField_management(fc, fld_name, fld_type, None, None, fld_length)


def createRectangle(x, y, w, h, sr):
    xmin = float(x) - float(w) / 2.0
    xmax = float(x) + float(w) / 2.0
    ymin = float(y) - float(h) / 2.0
    ymax = float(y) + float(h) / 2.0
    lst_pnts = []
    lst_pnts.append(arcpy.Point(xmin, ymin))
    lst_pnts.append(arcpy.Point(xmin, ymax))
    lst_pnts.append(arcpy.Point(xmax, ymax))
    lst_pnts.append(arcpy.Point(xmax, ymin))
    lst_pnts.append(lst_pnts[0])
    return arcpy.Polygon(arcpy.Array(lst_pnts), sr)


if __name__ == '__main__':
    main()‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍

Re: Python Script: Create a rectangle using coordinates, width and height atributes from DBF

XanderBakker — Sat, 11 Dec 2021 11:52:02 GMT

Oops, just noticed I made an mistake on line 43 - 44. It should be replaced by:

                polygon = createRectangle(x, y, w, h, sr)
‍‍‍

^{New: just updated code in post above...}

Re: Python Script: Create a rectangle using coordinates, width and height atributes from DBF

JoshuaBixby — Wed, 11 Jan 2017 21:19:15 GMT

Can you update your original code as well (maybe you did and I am missing the obvious)?

Re: Python Script: Create a rectangle using coordinates, width and height atributes from DBF

TimGattinger — Thu, 12 Jan 2017 16:47:24 GMT

Thanks, it looks great I'll try the code as soon as possible.. I just didnt understand where the X,Y coordinates come from...I created center points from an underlying shapefile, can I e.g. take the coordiunates form these points and just add them to the dbf and go on with the script you just wrote?

So..in your code are the X,Y coordinates meant to be the starting point for each rectangle, or sth like that?

Best, Tim

Re: Python Script: Create a rectangle using coordinates, width and height atributes from DBF

TimGattinger — Thu, 12 Jan 2017 18:27:03 GMT

After the adaptions I made, it still says 'global name 'fc' not defined'..do you have an idea?! Im quite new to the programming stuff btw..

Re: Python Script: Create a rectangle using coordinates, width and height atributes from DBF

BlakeTerhune — Thu, 12 Jan 2017 19:03:14 GMT

In line 36 of Xander's code where the SearchCursor is created, I think fc should be changed to tbl. However, it also looks like fld_oid is undefined on line 35; maybe should be fld_oid_in?

Re: Python Script: Create a rectangle using coordinates, width and height atributes from DBF

XanderBakker — Thu, 12 Jan 2017 19:38:22 GMT

Very valid comments Blake Terhune (+1)... will generate a dummy table with some random data and test the code, to see what needs to be changed.

Re: Python Script: Create a rectangle using coordinates, width and height atributes from DBF

XanderBakker — Sat, 11 Dec 2021 11:52:05 GMT

Yes, Blake Terhune was completely right! Those were errors indeed. Find below the corrected (and tested) code:

import arcpy

def main():
    import os

    arcpy.env.overwriteOutput = True

    # input dbf file, edit this !!!
    tbl = r'D:\Xander\GeoNet\DBF2Rectangles\testdata.dbf'

    # edit these field names !!!
    fld_oid_in = 'OID@'
    fld_X = 'X'
    fld_Y = 'Y'
    fld_width = 'Width'
    fld_height = 'Height'
    fld_oid_out = 'OID_DBF'

    # output feature class
    fc_out = r'D:\Xander\GeoNet\DBF2Rectangles\test.gdb\rectangles' # edit this !!!

    # define a spatial reference, edit this !!!
    sr = arcpy.SpatialReference(3857)  # example for WGS_1984_Web_Mercator_Auxiliary_Sphere

    # create output featureclass
    fc_ws, fc_name = os.path.split(fc_out)
    arcpy.CreateFeatureclass_management(fc_ws, fc_name, "POLYGON", None, None, None, sr)

    # add field OID DBF
    AddField(fc_out, fld_oid_out, "LONG", None)

    # insert cursor to store the results
    flds_out = ('SHAPE@', fld_oid_out)
    with arcpy.da.InsertCursor(fc_out, flds_out) as curs_out:

        # loop over dbf file
        flds = (fld_oid_in, fld_X, fld_Y, fld_width, fld_height)
        with arcpy.da.SearchCursor(tbl, flds) as curs:
            for row in curs:
                oid = row[0]
                x = row[1]
                y = row[2]
                w = row[3]
                h = row[4]
                polygon = createRectangle(x, y, w, h, sr)
                curs_out.insertRow((polygon, oid, ))


def AddField(fc, fld_name, fld_type, fld_length):
    if len(arcpy.ListFields(fc, fld_name)) == 0:
        arcpy.AddField_management(fc, fld_name, fld_type, None, None, fld_length)


def createRectangle(x, y, w, h, sr):
    xmin = float(x) - float(w) / 2.0
    xmax = float(x) + float(w) / 2.0
    ymin = float(y) - float(h) / 2.0
    ymax = float(y) + float(h) / 2.0
    lst_pnts = []
    lst_pnts.append(arcpy.Point(xmin, ymin))
    lst_pnts.append(arcpy.Point(xmin, ymax))
    lst_pnts.append(arcpy.Point(xmax, ymax))
    lst_pnts.append(arcpy.Point(xmax, ymin))
    lst_pnts.append(lst_pnts[0])
    return arcpy.Polygon(arcpy.Array(lst_pnts), sr)


if __name__ == '__main__':
    main()‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍

And the result for some random data:

Re: Python Script: Create a rectangle using coordinates, width and height atributes from DBF

TimGattinger — Fri, 13 Jan 2017 17:27:32 GMT

That's amazing thanks!! But it still doesn't work for me, when I execute the script it says:
Runtime error
Traceback (most recent call last):
File "<string>", line 69, in <module>
File "<string>", line 39, in main
RuntimeError: A column was specified that does not exist.

But I can't find the mistake..

Re: Python Script: Create a rectangle using coordinates, width and height atributes from DBF

XanderBakker — Fri, 13 Jan 2017 17:32:04 GMT

The first part to look at would be the lines 12 - 15 where the input fields are defined. Do you have fields with these names in you DBF?

fld_X = 'X'
fld_Y = 'Y'
fld_width = 'Width'
fld_height = 'Height'

If not, change these names (the part between the single quotes) to reflect the field names in you DBF.

In case that does no resolve the problem, could you share the DBF? Or if not, post a screenshot that shows the field names?

Re: Python Script: Create a rectangle using coordinates, width and height atributes from DBF

TimGattinger — Fri, 13 Jan 2017 17:40:35 GMT

Yes, I adapt it to the field names, whereby im not quite sure what 'fld_oid_out' was meant to be (? maybe just the ID for the output?)

Re: Python Script: Create a rectangle using coordinates, width and height atributes from DBF

TimGattinger — Fri, 13 Jan 2017 17:41:25 GMT

it looks like tgis for my case:
...     # edit these field names !!!
...     fld_oid_in = 'OID@'
...     fld_X = 'INSIDE_X'
...     fld_Y = 'INSIDE_y'
...     fld_width = 'width'
...     fld_height = 'length'
...     fld_oid_out = 'ID'

..And does it make a difference whether the dbf is stored in a GDB or not?

Re: Python Script: Create a rectangle using coordinates, width and height atributes from DBF

XanderBakker — Fri, 13 Jan 2017 18:05:30 GMT

At first sight there doesn't seem to be anything wrong with the definition of your fields. It could have been something with reserved field names, whereas ArcGIS in some cases renames them in the process and puts an underscore behind it.

The other part that I can think of is that when you look at a table you see the alias (in many cases the same as the actual field name), however, a field may have a different name than the ones shown. The script will work with the field name and not the alias. To verify this, you could enter the properties of the table, in the Fields tab you will see the list of fields. When you click on a field, you can see both the alias and the field name. Make sure the field names in the script refer to the field names and not the aliases.

It should not be a problem to use a table store in a geodatabase. The fld_oid_in refers to the ObjectID or OID field in the input using the "OID@" token. It adapts to the data source.

The fld_oid_out is a new field to be created in the output featureclass that will hold the object ID's from the input and allow to join attributes from the table to the output featureclass.

If possible it would be nice to be able to have access to the actual data to see what is going on.

Re: Python Script: Create a rectangle using coordinates, width and height atributes from DBF

TimGattinger — Fri, 13 Jan 2017 19:20:45 GMT

Hey,

You were right with the alias names (the fields were indeed renamed!). But still the same error message as before!

Would it be helpful if I send you my gdb (including the dbf file)?

Re: Python Script: Create a rectangle using coordinates, width and height atributes from DBF

XanderBakker — Sat, 14 Jan 2017 18:44:12 GMT

Hi tiga_2 , sharing the data would indeed be very helpful to trace the error.

Re: Python Script: Create a rectangle using coordinates, width and height atributes from DBF

XanderBakker — Wed, 18 Jan 2017 23:10:23 GMT

Hi Tim Gattinger , if you are going to share the data, you may also want to include some details about the ArcGIS Desktop version you are using.

Thanks in advance.

Re: Python Script: Create a rectangle using coordinates, width and height atributes from DBF

TimGattinger — Mon, 30 Jan 2017 16:55:38 GMT

Dear Xander,

am using ArcGIS Desktop 10.2.1. I attached my GDB plus the code I am using as wordDoc

Thanks for your help!

Re: Python Script: Create a rectangle using coordinates, width and height atributes from DBF

XanderBakker — Sat, 11 Dec 2021 11:52:08 GMT

Hi Tim Gattinger , I just had a look at your data and I noticed that the fields in the table you use, are defined as:

... and that there are no X and Y fields. In your code you define your fields like this:

fld_X = 'CentroidPOINT.INSIDE_X'
fld_Y = 'CentroidPOINT.INSIDE_Y'
fld_width = 'NABU_1.width'
fld_height = 'NABU_1.length'‍‍‍‍‍‍‍‍

When you have a point in the field name, that is normally the result of a join applied in ArcMap. When you acces the data using the path to the datasource, the datasource will not be aware of any joins you may have defined in ArcMap and therefore throw an error that the field does not exist. If you are sure about the field names, you can run the code in the Python windows of ArcMap, but you will have to access the data using the name in the Table of Contents.

So your line:

tbl = r'W:\Gattinger_Tim\GDB\rect_py.gdb\NABU_1'‍‍

... should be changed to:

tbl = 'NABU_1'‍‍

The alternative is to export the table with the join to a new table and this will create a physical result with the field that can be accessed using the path to the table. Be aware that the names of the fields will no longer contain dots, so you will have to adapt those names.

In order to simulate the result using your data, I took the "gewannstruktur" featureclass, created the X and Y fields based on the centroid of the polygons, joined this featureclass to the NABU_1 table and exported the result to a new table (NABU_2):

I used this table to generate the rectangles, using the following field definitions in the code:

fld_X = 'X'
fld_Y = 'Y'
fld_width = 'width'
fld_height = 'NABU_1_length'‍‍‍‍‍‍‍‍

The resulting featureclass is attached.