Future Development Goals¶

Dump arcpy¶

The arcpy module is available only to users who purchase ESRI’s ArcMap software. It’s principle advantage over most other GIS programming tools or API’s out there is that the user and help documentation is really good, and the “model builder” interface is a good baby step towards python programming, so it’s a good place for burgeoning GIS programmers to start learning. Alternatively, the gdal library is very powerful open source cross platform library with python bindings, but has disjointed documentation that can be intimidating and confusing. dnppy’s long term goal is to package the power of gdal into more easily understood functional wrappers akin to arcpy functions. Actually, ESRI’s ArcMap itself is built on top of some parts of the gdal binaries! Priority should always be placed on meeting the immediate needs of the GIS community and NASA data users, but the addition of new arcpy dependent functions should be avoided. If you’ve installed dnppy, you’ve already got an arcpy compatible version of gdal installed, and some dnppy functions already use gdal!

It would be rather inconsiderate of us to tell future developers, “please use gdal k-thanks” without giving them some kind of starter guide. Read more on gdal..

Python 3¶

Once dnppy is no longer tied to arcpy (which is what anchors dnppy to python 2.7), we will be free to embrace the future of the Python programming language. In the mean-time, there are some things we can be doing right now that will make the transition to Python 3 significantly easier.

Printing string output

String manipulations are very common even at the most basic level.In Python 2, users can use print "my string", but in Python 3 this is no longer acceptable! The print keyword has become a function in python 3. Furthermore, in line substitutions abide by slightly different rules. So, in order to institute good practice for the inevitable update, it costs us very little to write print statements that work in both 2.7 and 3.0. Therefore we use the format method on a string.

my_name = "Jwely"
my_age = 26

print "my name is " + my_name + " and my age is " + str(my_age)     # this is BAD
print("my name is {0} and my age is {1}".format(my_name, my_age))   # this is GOOD

Notice that you do not need to cast my_age as a string when using the format method, as it takes care of this on its own. You may find violations of this rule within dnppy, if you do, please fix it!