Network Analyst and Geoprocessing in the Background

Well, I never used wordpress, oh well. Anyway, I realized as much as I like twitter and such, I still need to blog for my own documentation of ideas and GIS techniques.

So here it goes, again:

So the last day or two I've been running in to this problem with using Network Analyst for geoprocessing. It seems that running it in the background in ArcCatalog doesn't work but running in the foreground in ArcMap works fine (I'm running 10.0 SP5-maybe 10.1 fixes this).

I've avoided scripting Network Analyst functions for a while now but decided to make the leap. So after much frustration and reading the Esri forums (which are still annoying since the migration), I found out it will only run in the foreground. I'm getting some weird server error. So no big deal, just sort of a crummy workaround.

nygeog.wordpress.com

My newer posts may be found at nygeog.wordpress.com.

I’m migrating to WordPress for two reasons;

1) My research group is changing our website hosting from a paid web programmer’s server to WordPress

2) It’s just sort of interesting for me to learn something new!

Python Code Block - Population Density (numerator zero and string to numeric)

Okay, so this morning, I've been dealing with two things. Well the first is that my ACS Census 2006-2010 conversion scripts create string fields for the variables. They should be numeric. I'll deal with that on its own. But this challenge was sort of interesting b/c it required two things. First off, I needed to calculate Population Density (per sq. km) but I've been having trouble with Python dealing with zero's (0) in the numerator for division when my added Field is non-nullable (I think if you add a field after the initial feature class creation you can't allow a field to be nullable, need to check on that though) and then converting and using a string value in my Code Block. I did a bunch of things wrong at first. My colleague's friend helped me figure this out over gchat by showing him my first code that didn't work. So thanks to him, though I don't know his name, but know he works at the EPA or did when my colleague was there. First off, I was only using a space, no comma in my Expression between !field_names!. Secondly, I noticed I needed to set my string equal using == rather than = or is. So here's the code that worked for me. Use it for Population Density Calculations just be sure to get rid of the float and the quotes if your Population variable is in fact numeric.

!B01003001E! is a string of the total population

!ALAND10! is land area in sq. meters (double)

Expression:

Calc(!B01003001E!, !ALAND10!)

Code Block:

def Calc(pop, land):

if pop == '0':

return 0

else:

return float(pop)/(land*0.000001)

2012 GIS Goals

Welcome to 2012. I'm about 26 days late.

Anyway, I thought I'd use my blog (that I barely post to anymore because of twitter) to mark some of my goals for 2012. 2011 started slow, but this fall I delved deeper into my Python work and web mapping work with Google Maps.

1. Become more proficient with Python, especially the other modules, iters, calendar, etc.

2. Learn GeoDjango, learn it.

3. Learn even more about the Google Maps API and Fusion tables.

4. Utilize Dropbox more for non-sensitive GIS data.

It was hard to not automatically #hashtag every other word, weird. Anyway, good luck to everyone in 2012 and I hope your GIS wishes come true.