topic Re: Problem with select analysis + copy rows in loop in Python Questions

Problem with select analysis + copy rows in loop

KONPETROV — Fri, 03 Apr 2015 14:49:28 GMT

Hi, i am trying to implement various combinations of tools trying to export some rows from a pnt shapefile based on a query (or while or for loop).I have a column (Condition) with values TRUE and FALSE and i want to export every row for the statement, Condition = "TRUE". However i only want those rows who respond to TRUE and if a FALSE follows i don't want to export nothing else, although after FALSE maybe there are more TRUE.

an example:

FID Condition H Wo FID Condition H Wo

0 TRUE 65 20 0 TRUE 65 20

1 TRUE 54 25 1 TRUE 54 25

2 TRUE 54 0 I want only these values ---> 2 TRUE with the rest of the fields 54 0

3 FALSE 65 25

4 TRUE 98 0

5 TRUE 23 5

These are the samples of code i tried, to export the rows based my statement :

import arcpy, os

fc = "c:/Task/data/In.shp"

outworkspace = "c:/Task/data/In.shp"

fields = ["FID", "Condition", "H", "Wo"]

with arcpy.da.UpdateCursor(fc, fields) as cursor:

for row in cursor:

while [row] = 'TRUE':

arcpy.CopyRows_management("In", "c:/Task/data/Out.shp")

and also with select analysis:

import arcpy, os

from arcpy import env

env.workspace = "c:/Task/data/In.shp"

fc = "c:/Task/data/In.shp"

fields = ["FID", "Condition", "H", "Wo"]

with arcpy.da.UpdateCursor(fc, fields) as cursor:

for row in cursor:

while [row] = 'TRUE':

arcpy.Select_analysis("In", "Out_s", '[Condition] = "TRUE"'))

But for some reason i always get an error.

Re: Problem with select analysis + copy rows in loop

DanPatterson_Retired — Fri, 03 Apr 2015 15:00:45 GMT

Why don't you do the process manually once, then copy and modify the python code snippet from the Results Window (under Customize menu). I have documented several examples of using this approach to develop scripts that employ Arctoolbox tools. Also, I am not sure which field you are querying nor what you are updating given you are using an update cursor.

Re: Problem with select analysis + copy rows in loop

BlakeTerhune — Fri, 03 Apr 2015 15:21:38 GMT

There is a lot of little things wrong with your code. Before I try creating new code, I have a question. It looks like you have a second condition you are using to filter your table, could you please describe that? Right now I see the only thing you check is that the Condition field is equal to "TRUE". What criteria did you use to eliminate FID 4 and 5?

Re: Problem with select analysis + copy rows in loop

KONPETROV — Fri, 03 Apr 2015 15:28:49 GMT

I want the procedure to stop when it finds a FALSE statement but i don't know how to write it, this is the criteria for the elimination of all values after the first false. I just want to do a check with while (while Condition = True) and copy only them until TRUE become FALSE.

Re: Problem with select analysis + copy rows in loop

BlakeTerhune — Fri, 03 Apr 2015 15:32:05 GMT

That's not reliable because you cannot guarantee the order in which the rows are returned. Could you describe in more detail why you only want to copy rows until it finds a FALSE?

Re: Problem with select analysis + copy rows in loop

JakeSkinner — Sat, 11 Dec 2021 16:15:49 GMT

Hi Kon,

Here is an example on how you can do this:

import arcpy
from arcpy import env
env.overwriteOutput = 1
env.workspace = r"C:\temp\python\test.gdb"

point = "Point"

list = []

with arcpy.da.SearchCursor(point, ["OID@", "Condition"]) as cursor:
    for row in cursor:
        if row[1] == 'True':
            x = row[0]
        elif row[1] == 'False':
            list.append(x)

del cursor

#convert list to string
list = str(list).strip('[]')

#create a feature layer of only features within list
arcpy.MakeFeatureLayer_management(point, "pointLyr", "OBJECTID in (" + list + ")")

#create feature class from feature layer
arcpy.CopyFeatures_management("pointLyr", "pointSelection")

Re: Problem with select analysis + copy rows in loop

KONPETROV — Fri, 03 Apr 2015 15:39:40 GMT

Well I am not trying to update anything I am using update cursor trying to iterate from row to row. I cannot think another way. In Python I know how to do it but the combinations with ArcPy cause me a big headache. Can you paste a link to your approach examples?

Re: Problem with select analysis + copy rows in loop

BlakeTerhune — Sat, 11 Dec 2021 16:15:52 GMT

for row in cursor:
    if row[1] == 'True':
        x = row[0]
    elif row[1] == 'False':
        list.append(x)

Wouldn't that only get the last row that is TRUE? x gets replaced each time it's true and only gets appended to list when it finds a FALSE. Seems like you'd have to do something like

for row in cursor:
    if row[1] == 'True':
        list.append(row[0])
    elif row[1] == 'False':
        break

Re: Problem with select analysis + copy rows in loop

KONPETROV — Fri, 03 Apr 2015 15:48:46 GMT

These are distances betweens points along a route. When i have a false statement that means that i must stop there and copy all the records until that point. That is why i want all the records until the first FALSE Statement.

Re: Problem with select analysis + copy rows in loop

KONPETROV — Fri, 03 Apr 2015 16:02:37 GMT

Jake thanks for your response but i tested it with the correction of Mr. Blake T and i got an "ERROR 000230: Failed selecting with OBJECTID in () Failed to execute (MakeFeatureLayer). "

Re: Problem with select analysis + copy rows in loop

JakeSkinner — Fri, 03 Apr 2015 16:11:09 GMT

I misunderstood your initial question. I thought you only wanted the first True condition before the False condition. If you want all True conditions, Blake's update should work.

It looks like the code is failing when you are trying to create the Feature Layer. Can you post the code you tried?

Re: Problem with select analysis + copy rows in loop

KONPETROV — Fri, 03 Apr 2015 16:28:07 GMT

right away:

import arcpy

... from arcpy import env

... env.overwriteOutput = 1

... env.workspace = "c:\Task\Data\In.mxd"

... point = "route"

... list = []

... with arcpy.da.SearchCursor(point, ["OID@", "Condition"]) as cursor:

... for row in cursor:

... if row[1] == 'True':

... list.append(row[0])

... elif row[1] == 'False':

... break

...

... del cursor

...

... #convert list to string

... list = str(list).strip('[]')

...

... #create a feature layer of only features within list

... arcpy.MakeFeatureLayer_management(point, "pointLyr", "OBJECTID in (" + list + ")")

...

... #create feature class from feature layer

... arcpy.CopyFeatures_management("pointLyr", "pointSelection")

Re: Problem with select analysis + copy rows in loop

BlakeTerhune — Fri, 03 Apr 2015 16:36:24 GMT

I think your workspace has to be a geodatabase, not an MXD. Also, the point variable is the name your input feature class (not a the layer name from an MXD).

EDIT

You may also need to change the strings in the if statement from "True" to "TRUE" and "False" to "FALSE" so it matches your data.

Re: Problem with select analysis + copy rows in loop

JakeSkinner — Fri, 03 Apr 2015 16:39:02 GMT

Are you working with a route Event Layer? The event layer most likely does not have a field called OBJECTID. Open the attribute table and see what this field may be. For example, it may be FID.

Once you have this field, update the arcpy.MakeFeatureLayer_management command. Ex:

arcpy.MakeFeatureLayer_management(point, "pointLyr", "FID in (" + list + ")")

Re: Problem with select analysis + copy rows in loop

KONPETROV — Fri, 03 Apr 2015 16:45:43 GMT

Jake no i don't have an Event Layer. i just have a shapefile with many pnts and fields.

Re: Problem with select analysis + copy rows in loop

JakeSkinner — Fri, 03 Apr 2015 16:48:40 GMT

The same will apply to a shapefile. The shapefile will not have a field called OBJECTID.

Re: Problem with select analysis + copy rows in loop

JakeSkinner — Fri, 03 Apr 2015 16:54:25 GMT

Also, you will need to update the last line to write the output to a shapefile or geodatabase. Ex:

arcpy.CopyFeatures_management("pointLyr", r"C:\temp\pointSelection.shp")

Re: Problem with select analysis + copy rows in loop

KONPETROV — Sat, 04 Apr 2015 19:08:57 GMT

Jade thanks a lot for your reply, but when i test it i get back an 00230 error: ERROR 000230: Failed selecting with FID in () Failed to execute (MakeFeatureLayer).

000230 : Failed selecting with <value>.

Re: Problem with select analysis + copy rows in loop

DanPatterson_Retired — Sat, 04 Apr 2015 19:18:47 GMT

Did you check the help file on that error message? In short, it means that the query doesn't work. Did you try it manually? Did you verify that it worked? Did you read the help topic on about building an SQL expression? When you can perform the tasks manually, documenting what you did and what worked, you will have the workings of a script. I will emphasize that using the Results window (see the Customize menu) and using tools from ArcToolbox is the fastest way of building a script that works from start to finish.

Re: Problem with select analysis + copy rows in loop

KONPETROV — Sat, 04 Apr 2015 20:09:30 GMT

Mr Patterson i read it, and i saw the query again. I guess something is going wrong

with FID in (" + list + ")"

but i have nerer use an expression like this to correct it. In my mind for my task was only select analysis in a while loop, this is a different approach and propably the correct but something is wrong in the code.

Manually i did it with my code and it worked, but the problem i have here is that i cannot do it for an example like this I shew you in my example, where TRUE and FALSE statements are mixed.

You mentioned that with results window again, i always see what the results window appear and here isn't not showing something different than the error in Python window. It just says :

Invalid SQL statement was used and

Failed to execute (Make Feature Layer)