Defining features in a list

[M Whitman]

Good Morning,

I have been recently trying to define all of the features in a list but have been running into errors. I would like to define the features similar tothe following print statement. Any advice would be appreciated. I'm trying to transition my output from a text file to excel and if I can loop through my lists and define them that transition will be cleaner.

Many Thanks,

-Matt

#Author: MGW
#2012
import os, datetime, sys, arcpy, xlrd
from arcpy import env
submission = "Rev.mdb"
env.workspace = "C:/temp/"+submission+"/Water"

#Get Submission totals
fclist = sorted(arcpy.ListFeatureClasses("*"))
for fc in fclist:
print fc+"="+str(arcpy.GetCount_management(fc).getOutput(0))

print "Complete"
raw_input("Press ENTER to close this window")

Output Generated
WATER_Net_Junctions=312
WS_Hyd=484
WS_Mains=2752
WS_Node=4722
WS_Vlvs=1078
WS_WatLats=3661
WS_WatMtrs=3662
WTRPLANTS_points=0
WTRPUMPSTA_points=0
WTRTANKS=0
WTR_ARV=10
WTR_MISC=0
Complete
Press ENTER to close this window

#Get Submission totals
fclist = sorted(arcpy.ListFeatureClasses("*"))
for fc in fclist:
fc=str(arcpy.GetCount_management(fc).getOutput(0))
#TEST
print WS_Hyd


print "Complete"
raw_input("Press ENTER to close this window")

Output Generated
Traceback (most recent call last):
File "C:\Documents and Settings\mattheww\Desktop\Copy of QAQCexce_2.py", line 14, in <module>
print WS_Hyd
NameError: name 'WS_Hyd' is not defined

 

[Dave Angel]

Good Morning,

I have been recently trying to define all of the features in a list but have been running into errors.

How proficient are you in Python? Could you possibly use terms which
make sense to someone who doesn't know this arcGIS program? I'm just
making a wild guess that that's what you're importing with the arcpy
import. When I do an internet search on arcpy, I see lots of tutorials,
training, etc. I didn't find a mailing list, but there probably is one.

The term that needs translating is "feature.'

I would like to define the features similar to the following print statement. Any advice would be appreciated. I'm trying to transition my output from a text file to excel and if I can loop through my lists and define them that transition will be cleaner.

Many Thanks,

-Matt

#Author: MGW
#2012
import os, datetime, sys, arcpy, xlrd
from arcpy import env
submission = "Rev.mdb"
env.workspace = "C:/temp/"+submission+"/Water"

#Get Submission totals
fclist = sorted(arcpy.ListFeatureClasses("*"))
for fc in fclist:
print fc+"="+str(arcpy.GetCount_management(fc).getOutput(0))

print "Complete"
raw_input("Press ENTER to close this window")

Output Generated
WATER_Net_Junctions=312
WS_Hyd=484
WS_Mains=2752
WS_Node=4722
WS_Vlvs=1078
WS_WatLats=3661
WS_WatMtrs=3662
WTRPLANTS_points=0
WTRPUMPSTA_points=0
WTRTANKS=0
WTR_ARV=10
WTR_MISC=0
Complete
Press ENTER to close this window

#Get Submission totals
fclist = sorted(arcpy.ListFeatureClasses("*"))
for fc in fclist:
fc=str(arcpy.GetCount_management(fc).getOutput(0))
#TEST
print WS_Hyd

There's no variable WS_Hyd, so what did you expect it to do? Do you
want to be able to fetch the values by name that were printed above? if
so, I'd suggest a dict, not a list. Lists don't have names for each
element, just indices.

print "Complete"
raw_input("Press ENTER to close this window")

Output Generated
Traceback (most recent call last):
File "C:\Documents and Settings\mattheww\Desktop\Copy of QAQCexce_2.py", line 14, in <module>
print WS_Hyd
NameError: name 'WS_Hyd' is not defined

As a very rough start, perhaps you could try something like this.
Remember i don't have the docs, so the only clue I've got is the stuff
you printed from the first loop.

table = {}

fclist = sorted(arcpy.ListFeatureClasses("*"))
for fc in fclist:
table[fc] = +str(arcpy.GetCount_management(fc).getOutput(0))

Now, if you want to print the value for WS_Hyd, it should be available as

print "value = ", table["WS_Hyd"]

If you're sufficiently advanced, i could suggest a class-based solution
where you'd access items by
mytable.WS_Hyd

But if you're not yet familiar with class definition and attributes and
such, we'd better not go there.

 

[M Whitman]

Dave- By features I was refering to items in the list. For background the arcpy module is used for geoprocessing of geographic information. I'm using my script to get totals for features in a dataset that I receive on a regular basis- for example total number of hydrants, total number of hydrants with null or missing attributes, and total number of hydrants with outlining attributes.

I am experienced particularly with the arcpy module and I am trying deligently to become more experienced with Python in general. My goal is to fetchvalues by name and then print output by name. print WS_Hyd and then see "484". I have some experience with class definition but a dictionary might be the way to go. I was understanding the response of the Arcpy module buthadn't understood why the list wasn't being defined in my previous loop statement. I appreciate the response. I will look into dict if you have a class definition suggestion I will run with that. Thanks

 

[Jean-Michel Pichavant]

Good Morning,

I have been recently trying to define all of the features in a list but have been running into errors. I would like to define the features similar to the following print statement. Any advice would be appreciated. I'm trying to transition my output from a text file to excel and if I can loop through my lists and define them that transition will be cleaner.

Many Thanks,

-Matt

#Author: MGW
#2012
import os, datetime, sys, arcpy, xlrd
from arcpy import env
submission = "Rev.mdb"
env.workspace = "C:/temp/"+submission+"/Water"

#Get Submission totals
fclist = sorted(arcpy.ListFeatureClasses("*"))
for fc in fclist:
print fc+"="+str(arcpy.GetCount_management(fc).getOutput(0))

print "Complete"
raw_input("Press ENTER to close this window")

Output Generated
WATER_Net_Junctions=312
WS_Hyd=484
WS_Mains=2752
WS_Node=4722
WS_Vlvs=1078
WS_WatLats=3661
WS_WatMtrs=3662
WTRPLANTS_points=0
WTRPUMPSTA_points=0
WTRTANKS=0
WTR_ARV=10
WTR_MISC=0
Complete
Press ENTER to close this window

#Get Submission totals
fclist = sorted(arcpy.ListFeatureClasses("*"))
for fc in fclist:
fc=str(arcpy.GetCount_management(fc).getOutput(0))
#TEST
print WS_Hyd


print "Complete"
raw_input("Press ENTER to close this window")

Output Generated
Traceback (most recent call last):
File "C:\Documents and Settings\mattheww\Desktop\Copy of QAQCexce_2.py", line 14, in <module>
print WS_Hyd
NameError: name 'WS_Hyd' is not defined

I'm not sure I've understood everything, is this something you're
searching for:

fcDict = dict([(str(fc),
str(arcpy.GetCount_management(fc).getOutput(0))) ) for fc in
sorted(arcpy.ListFeatureClasses("*")) ])

print fcDict
print fcDict['WS_Hyd']

This is difficult to read because of the online statement, but it does
basically the following pseudo code:

fcDict = dict([(feature.name, feature.value) for feature in featureList ])

Cheers,

JM

 

[Dave Angel]

Dave- By features I was refering to items in the list. For background the arcpy module is used for geoprocessing of geographic information. I'm using my script to get totals for features in a dataset that I receive on a regular basis- for example total number of hydrants, total number of hydrants with null or missing attributes, and total number of hydrants with outlining attributes.

I am experienced particularly with the arcpy module and I am trying deligently to become more experienced with Python in general. My goal is to fetch values by name and then print output by name. print WS_Hyd and then see "484". I have some experience with class definition but a dictionary might be the way to go. I was understanding the response of the Arcpy module but hadn't understood why the list wasn't being defined in my previous loop statement.

There is a list fclist being defined, just before the loop. But that
list contains the names of the "features" not the values. So if you
wanted, you could make a second list containing the values, or you could
even make a list containing tuples with name & value. But assuming
there's no particular ordering you care about, that's what a dictionary
is good at.

In either case that loop is not creating extra variables with names like
WS_Hyd. Creating variables with arbitrary names from data can only be
done with code that's dangerous and prone to injection attacks. You can
avoid the problem by putting them in some namespace, either a
dictionary, or a namedtuple, or a custom class.

I appreciate the response. I will look into dict if you have a class definition suggestion I will run with that. Thanks

Anyway, once you have the dictionary, you can indeed work on the values
in it, in various ways.

table = {}

fclist = sorted(arcpy.ListFeatureClasses("*"))
for fc in fclist:
table[fc] = +str(arcpy.GetCount_management(fc).getOutput(0))



Now you can use your captured data to do further processing. Simplest example printing. Suppose order doesn't matter:

for key in table.iterkeys():
print key, "=", table[key]

You could also do this as:

for key, value in table.iteritems():
print key, "=", value

If you want them in the original order, you can use your fclist, which is a list of keys:

for key in fclist:
print key, "=", table[key]

And of course if you want any particular one, you can do

print table["WS_hyd"]

Note that in the last case, if you typed the literal key wrong, or if the arcpy removed or renamed one of the keys, you'd get an exception there. To avoid that, you might do something like:

key = "WS_hyd"
if key in table:
print table[key]

 

[Dennis Lee Bieber]

for fc in fclist:
fc=str(arcpy.GetCount_management(fc).getOutput(0))

This does not do what you think it does.

fc first is bound to the first element of the list fclist

Then, fc is bound to the string representation of whatever the stuff
on the right side evaluates into..

I suspect you need to study the library reference manual on
"dictionaries"...