topic Re: Loop issue in Python Questions

Loop issue

CliveSwan — Tue, 22 Dec 2015 17:19:19 GMT

I have a list of shapefiles that I need to select within a loop, to see if the file is there or not.

I tried several loops if, elif ... Just get an error???

I would appreciate any suggestions, to get this working.

#check file exists here?

fcList = arcpy.ListFeatureClasses()

for shapefile in fcList:

if shapefile == "Bus Stops":

print "1" ++ shapefile

elif shapefile == "Cluster_Sites":

print "2" ++ "shapefile"

elif shapefile == "Highway Boundary":

print "3" ++ "shapefile"

elif shapefile == "Street Lighting":

print "4" ++ "shapefile"

elif shapefile == "Road_Traffic_Collisions":

print "5" ++ "shapefile"

else:

print "end"

The code prints:

end

There are 3 shapefiles in the directory.

There could be 0 to10 shapefiles

Re: Loop issue

DarrenWiens2 — Tue, 22 Dec 2015 17:30:38 GMT

Have you set the workspace environment? That is a necessary step 1.

Refer to help here.

Re: Loop issue

DanPatterson_Retired — Tue, 22 Dec 2015 17:31:33 GMT

could you format your code using code blocks since there are indentation errors which may be real or the result of copying/pasting/font issues

Re: Loop issue

ChrisSmith7 — Tue, 22 Dec 2015 17:32:35 GMT

Clive,

Right off the bat, you have some syntax issues with ++ in your string concatenation (as well as some indentation issues - maybe just artifacts?). Also, you are referring to shapefile as an object and "shapefile" as a string. Try fixing that, and if it still doesn't work, print shapefile to make sure you know what it's doing. Lastly, are you in the right workspace? I don't see any code setting this...

Re: Loop issue

CliveSwan — Tue, 22 Dec 2015 17:50:00 GMT

datadir = arcpy.env.workspace = r"D:/DATA/HML"

try:

# If directory doesn't exist make it

if not os.path.isdir(datadir):

os.mkdir(datadir)

# Change the local directory to where you want to put the data

os.chdir(datadir)

#check file exists here?

fcList = arcpy.ListFeatureClasses()

for i in fcList:

if i == "Bus Stops":

print "1" ++ shapefile

elif i == "Cluster_Sites_2014":

print shapefile

else:

print "2"

except:

print"error"

There code runs, the appearance is copy/paste.

If the indentation was wrong, it would not compile!!

It prints:

I need the loop to work.

If the file exists it runs a command, then jumps to the next item.

If the file does not exist it jumps to the next item.

Re: Loop issue

ChrisSmith7 — Tue, 22 Dec 2015 17:55:40 GMT

In your code block, where is shapefile coming from? You still have an issue with your concatenation:

print "1" ++  shapefile

That should result in something like bad operand type for unary +: 'str'

Re: Loop issue

ChrisSmith7 — Sat, 11 Dec 2021 15:47:28 GMT

Also, try just printing your item:

for i in fcList:
   print i

Re: Loop issue

DarrenWiens2 — Tue, 22 Dec 2015 18:01:50 GMT

If you print the list returned by ListFeatureClasses, you may notice that shapefiles include ".shp". Try comparing against, for example, "Cluster_Sites_2014.shp" rather than "Cluster_Sites_2014".

Re: Loop issue

CliveSwan — Tue, 22 Dec 2015 18:04:46 GMT

Hi Chris,

If I type:

fcList = arcpy.ListFeatureClasses()

for i in fcList:

print i

Then I get the list of shapefiles as expected.

Cluster_sites.shp

Fixed and Mobile Camera.shp

Road_Traffic_Collisions.shp

The aim is to use the if, elif block to use the CopyFeature command, if the shapefile exsists.

Thanks,

Clive

Re: Loop issue

CliveSwan — Tue, 22 Dec 2015 18:06:47 GMT

fcList = arcpy.ListFeatureClasses()

for i in fcList:

print "1" ++ shapefile

Returns an error

Re: Loop issue

CliveSwan — Tue, 22 Dec 2015 18:13:26 GMT

Hi Darren,

Thanks, when I added the .shp the script worked.

Got back

Cluster_sites.shp

Fixed and Mobile Camera.shp

Road_Traffic_Collisions.shp