topic Re: Replace character from attributes in Python Questions

Replace character from attributes

CCWeedcontrol — Sat, 11 Dec 2021 22:48:23 GMT

I need to remove forward slashes from the attributes in a layer. I need to remove the first \ and last \ and replace the double \\ with just one \. I would appreciate any help. Thanks.

Currently the attributes looks like this.

\R2\\M1\

\M1\\M1\\C2\

\AG\\R2\\M1\\R2\

I need it to look like the following

R2\M1

M1\M1\C2

AG\R2\M1\R2

I tried the following but got error "TypeError: argument of type 'NoneType' is not iterable" on line if '\\' if '\\' in row[0]: #if a double quote is in the string returned.

with arcpy.da.UpdateCursor("In_memory\LayerTest", "ZONING_CODE") as cursor:
    for row in cursor:
         if '\\' in row[0]: #if a double quote is in the string returned,  
            row[0]=row[0].replace('\\','\\') #replace that double quote with an empty string (removes it)  
            cursor.updateRow(row)
    del row‍‍‍‍‍‍

Re: Replace character from attributes

DanPatterson_Retired — Sat, 11 Dec 2021 22:48:26 GMT

throw a print statement in between line 2 and 3... it appears that 'None' (aka a null) is being returned for row[0].

Also in python ...

a = "\\"
a.replace("\\", "")

a = "\\\\"
a.replace("\\\\", "\\")
Out[16]: '\\'‍‍‍‍‍‍

Re: Replace character from attributes

NeilAyres — Fri, 28 Apr 2017 08:46:04 GMT

Yes a Null is being returned.

You may want to wrap another if around the row[0] checking.

if row[0] or len(row[0]) > 0:‍

Re: Replace character from attributes

CCWeedcontrol — Sat, 11 Dec 2021 22:48:29 GMT

do you mean an elif, i am not sure i am understand how to wrap another if around the row[0]

with arcpy.da.UpdateCursor(ZT1, "ZONING_CODE") as cursor:
    for row in cursor:
        if '\\\\' in row[0]: #if a double quote is in the string returned,
            if row[0] or len(row[0]) > 0:
                row[0]=row[0].replace('\\\\','\\') #replace that double quote with an empty string (removes it)
        
            
            cursor.updateRow(row)‍‍‍‍‍‍‍‍

Re: Replace character from attributes

CCWeedcontrol — Sat, 11 Dec 2021 22:48:31 GMT

I put a print row in between lines 2 & 3.

with arcpy.da.UpdateCursor(ZT1, "ZONING_CODE") as cursor:
    for row in cursor:
        print row
        if '\\\\' in row[0]: #if a double quote is in the string returned,  
            row[0]=row[0].replace('\\\\','\\') #replace that double quote with an empty string (removes it)  
            cursor.updateRow(row)
    del row‍‍‍‍‍‍‍

I get alot of

[u'\\AG\\']
[u'\\AG\\\\C1\\']

[u'\\R1\\']

[u'\\RR\\']
[u'\\AG\\\\RR\\']
[u'\\AG\\']
[u'\\AG\\\\RR\\']
[u'\\CR-M1\\']

Traceback (most recent call last):
File "C:\GIS\Python\ParcelTool\SpatialJoinTest.py", line 4, in <module>
if '\\\\' in row[0]: #if a double quote is in the string returned,
TypeError: argument of type 'NoneType' is not iterable

Re: Replace character from attributes

CCWeedcontrol — Sat, 11 Dec 2021 22:48:34 GMT

I was able to remove the double "\\" from within attributes . It didn't how ever remove the \ in the begging or the end. I would appreciate any help please.

\R2\\M1\ ----> \R2\M1\

\M1\\M1\\C2\ -----> \M1\M1\C2\

\AG\\R2\\M1\\R2\ -----> \AG\R2\M1\R2\

Current Code

with arcpy.da.UpdateCursor("In_memory\LayerTest", "ZONING_CODE") as cursor:
    for row in cursor:
        #print row
        #if row[0] or len(row[0]) > 0:
        if "\\\\" in row[0]: #if a double quote is in the string returned,
            for row in cursor:
                if row[0] or row[0] > 0:
                    row[0]=row[0].replace("\\\\","\\") #replace that double quote with an empty string (removes it)  
                    cursor.updateRow(row)
    del row‍‍‍‍‍‍‍‍‍‍

Re: Replace character from attributes

DanPatterson_Retired — Sat, 11 Dec 2021 22:48:37 GMT

you could slice before you update as in this example

row0 = 'abcdef'

row0 = row0[1:-1]

row0

'bcde'‍‍‍‍‍‍‍

Re: Replace character from attributes

CCWeedcontrol — Sat, 11 Dec 2021 22:48:39 GMT

apologies for my slowness. I tried the following but got error on line 7.

cursor.updateRow([row[0][1:-1]])
TypeError: 'NoneType' object has no attribute '__getitem__'

ZT1 = "In_memory\ZoningTest1"
arcpy.MakeFeatureLayer_management("In_memory\ZoningTest", ZT1)

with arcpy.da.UpdateCursor(ZT1, "ZONING_CODE") as cursor:
    for row in cursor:
        print row
        cursor.updateRow([row[0][1:-1]])
    del row
   

with arcpy.da.UpdateCursor(ZT1, "ZONING_CODE") as cursor:
    for row in cursor:
        #print row
        #if row[0] or len(row[0]) > 0:
        if "\\\\" in row[0]: #if a double quote is in the string returned,
            for row in cursor:
                if row[0] or row[0] > 0:
                    row[0]=row[0].replace("\\\\","\\") #replace that double quote with an empty string (removes it)
                    cursor.updateRow(row)
    del row‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍

Re: Replace character from attributes

DanPatterson_Retired — Mon, 01 May 2017 18:58:59 GMT

I have no clue why you have to two cursors going on.

Presumably in and around line 17, row[0] is returning a string, which you then use the replace thing to get rid of the double quotes, which you then reassign back to row[0]. In line 17, why don't you call it 'val', so

val = row[0].replace(blah blah)

row[0] = val[1:-1]

cursor.updateRow(row)

Re: Replace character from attributes

CCWeedcontrol — Sat, 11 Dec 2021 22:48:42 GMT

looks like it kind of worked....? it removed some of the \ but not all. See attached pic

with arcpy.da.UpdateCursor(ZT1, "ZONING_CODE") as cursor:
    for row in cursor:
        #print row
        #if row[0] or len(row[0]) > 0:
        if "\\\\" in row[0]: #if a double quote is in the string returned,
            for row in cursor:
                if row[0] or row[0] > 0:
                    val = row[0].replace("\\\\","\\") #replace that double quote with an empty string (removes it)
                    row[0]=val[1:-1]
                    cursor.updateRow(row)
    del row‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍

Re: Replace character from attributes

DanPatterson_Retired — Mon, 01 May 2017 21:16:00 GMT

could you show a screen grab of the original table field... it is hard to replicate what you are talking about since a backslash is an escape character in python and what you report as inputs is hard to match for testing without having to add extra \'s which you suggest aren't there. This may be part of the issue

Re: Replace character from attributes

JoshuaBixby — Sat, 11 Dec 2021 22:48:45 GMT

Does the following do what you want:

with arcpy.da.UpdateCursor("In_memory\LayerTest", "ZONING_CODE") as cursor:
    for code, in cursor:
        if code:
            cursor.updateRow([code.strip("\\").replace("\\\\","\\")])‍‍‍‍

Re: Replace character from attributes

CCWeedcontrol — Mon, 01 May 2017 21:46:48 GMT

sure here you go.

As for why there are \ in the attribute fields is because some parcel can have more than one zoning zone and is why you would see AG\C1\M1. I couldn't use a dash ( - ) because some of our zones are CR-RR (CONDITIONAL REZONE - RURAL RESIDENTIAL) and RR(RURAL RESIDENTIAL) which are different. so if these two zoning zones were part of a parcel it would have shown as CR-RR-RR and would have been confusing.

Re: Replace character from attributes

DanPatterson_Retired — Mon, 01 May 2017 21:56:41 GMT

Then try Joshua's suggestion ... a.strip("\\").replace("\\\\","\\") ... but you may as well go whole tilt and fix it up altogether

a.strip("\\").replace("\\\\","/")
'AG/R2/M1/R2'

Re: Replace character from attributes

CCWeedcontrol — Tue, 02 May 2017 15:04:13 GMT

Thanks Dan and Joshua.