Geography 293: Geospatial Analysis with Python

Chapter 3: 

• Geoprocessing allows you to perform spatial analysis and modeling as well as automate GIS tasks
• Types of tools in ArcGIS Pro
  • Built-in tools
  • Script tools
  • Model tools
• Chapter is in depth about geoprocessing tools (already know how to use)
• Batch processing – execute single tool multiple times using different parameters without further intervention
• Model builder is can help build a sequence of geoprocessing tools that flow through a visual model
• Can also use scripting to build model
  • Modelbuilder = visual based
  • Python = text based
• Scripting has functions that modelbuilder does not have
• You can schedule python script to run at certain times 
  • Good for routine checks

Chapter 4:

• Chapter covers fundamentals of Python language
• Several different data types: strings, numbers, Booleans, lists, tuples, dictionaries
• Two numerical data types
  • Integers (whole numbers)
  • Floats (fractional numbers)
• Booleans contain only true and false values
• // is floor division
• % is modulus
• ** is exponents
• A set of characters surrounded by quotation marks is called a string literal, or string
• Do not copy and paste code – curly quotation marks will create error
• Can use str() to put a number into a string 
• Function is like a little program that is used to carry out an action
  • Ex: int()  str()  print()  type()
• Method is a function that is couple to an object like a number, string, or list
• The book is giving us a lot of examples of different things to do with the python and there are so many little nuances
• == to see if two things have the same value
• This chapters goes through all the different examples how to use python script – a lot of info, alot to try and take in

Chapter 1:

• Scripting language
  • Automating certain functionality within another program
• Programing language
  • Development of more sophisticated multifunctional applications
• Python is scripting language of choice for ArcGIS Pro
• Used to make redundant tasks/ large amounts processed faster and more efficient
• The example scripting scared me as I have never coded in my life
• Python is more basic than C++, easier to work with
• Python is both a scripting and programming language

Chapter 2:

• IDE: integrated development environments
• Scripting is a list of commands that can be run by a program
• Work with python in so-called command line or command prompt
• Use the command line that is provided with ArcGIS Pro
  • Want to use arcgispro-py3
• IDLE: Integrated DeveLopment Environment
  • “Python Shell”
• So when doing my very first line of code I already got errors…
  • I went and looked at past students and it seems I am not the only one to have run into this problem
  • Since an error came up I did not know how to make the shortcut on the desktop
• >>> is prompt
• Different colors are assigned to different parts of the script
• Writing script vs code different
  • Script menu – file > new file and this opens new untitled window (script window)
• Spyder: Scientific Python Development Environment
• Package info outdated (dif buttons)
• Hard time trying to get Spyder short cut
• Python scripts = modules 

Final: 

• For the final project, I chose Chapter 5 which is based on Geoprocessing with Python
• Here, I used the dataset from my 191 Finals and hard-coded the “Clip – Analysis” tool for the Olentangy School District. I clipped all other (four) shapefiles to fit into this district, so only the data from this particular area could be seen 
• I had no motives for doing so except to see how these data files intersect and if I can actually put into use whatever I’ve learned from the chapter. 
• Having the dataset from 191 helped as I was just redoing the project in a much more elaborate way without using tools that were developed by some other programmer but by using my own code. 
• Here are some of my pictures: (Forgot to take them while I actually did this so I had to re-do it, in order to get “proof” that I actually did it): 

• For the second chapter I chose Chapter 6, I know you said they need to be between 1-4 and 5-8 but I found 5 and 6 the only ones to be actually application based. 
• Chapter 6 is based on Exploring spatial data so I started by using functions like Exists, and Describe to get started.
• Exists returns true and false depending on if a dataset exists and describe, describes the data set of a file. A function shapeType can also be used with Describe the shape type of a dataset. 
• I also played around with List_Fields() and List_Files.

Here are the pictures for that: 

I enjoyed taking this class a lot! Overall, I didn’t have much trouble completing tasks except getting the Python Terminal set up. One piece of advice I would have would be for prospective students to take 191 before GIS 193. That class helped me a lot with understanding GIS concepts before I learn how to use Python to implement them.

Chapter 7: 

• This chapter was mainly about debugging and how to fix errors when coding. 
• I have done this before my computer science classes, and debugging has become an easier task for me now. 
• I’ve already been taught a lot of the techniques mentioned in the chapter through my professors so I was able to get through this chapter easily.

Chapter 8: 

• This chapter was about manipulating spatial and tabular data and using concepts learned in past chapters for application. 
• I also came across the term cursor – a database technology term for accessing a set of records in a table, and its types( search, insert, update) 
• These functions are essentially used to insert, update, or search things through tables.
• The Cursor  also has other functions like delete and reset. 
• The chapter also talks about working with SQL expressions and text and CSV files. 
• I’m still learning SQL so it took me a while to understand the syntax
• It is also interesting to learn that a lot of these tools that we used for GIS 191 and 192 are made using Python. 

Chapter 5: 

• This chapter introduces ArcPy and geoprocessing using Python
• I began with setting up my workspace which I had done before for GIS 191 
• The textbook also mentioned detailed changes to the environment like the env size, XY tolerance, etc. 
• The chapter mentioned that the key to getting the tool to run right is to get the parameters right. 
  • Usually, they are just: input datasets, tool features, and output datasets 
  • Optional parameters are enclosed in {}   
• I ran the Clip feature using the syntax instructions given in the textbook.    

Chapter 6: 

•  This chapter was all about exploring spatial data 
• This chapter introduced some new functions in ArcPy, and also how to perform batch processing more efficiently. 
• ArcPy has list functions that include: ListFields(), ListIndexes, ListDatasets(), ListWorkspaces(), and ListVersions()
• I also noticed that some of the function names had been changed in ArcGIS Pro when compared to the textbook.\
• The chapter also mentioned some built-in functions for lists that were mentioned in Chapter 4 before like len(returns the length of the list), sort(sorts the list), etc. 

 Chapter 3: 

• The chapter gets started with geoprocessing and how to use it in parallel with the Python Window. 
• Getting the Geoprocessing pane to open and understanding how it works was easy for me as I’ve used some of the tools for GIS 191
• I came across three different types of tools: 
  • Built-in tools: Built with compiled programming languages like C++ For example The Clip Tool 
  • Script Tools: Built using scripting languages like Python. For example Mean Center. 
  • Model Tools: Built using models like Model Builder. For example My Model  
• The dialog box is also something that I’m well acquainted with due to GIS 191
• I also used a map from one of the GIS 191 databases to try the “Clip” and “Intersect” tools
• I also came across the Environment Settings in the Analysis Tab, which can be specified for better efficient usage of the tools. 
• These environment settings can be coded, or used through individual tools as well \
• I also came across Batch Processing, which is running the same tools multiple times with different parameters. Dynamic naming of the tool’s output datasets must receive special consideration so that a unique name is used for every iteration of the batch tool. Batch tool outputs are dynamically named using the %Name% variable in output parameters.t
• Batch mode can also take in multiple raster variables and determine multiple statistics in one go 
• Then I used the Model Builder. I had used this before for GIS 191. Unfortunately, the dataset I was using did not have variables of different kinds, which posed a problem in connecting the shapes, I believe, But I did not fret about it as I had done this before. 
• For scripting, I noticed that some of the ways, the code for Clip(Analysis Tool) worked had been changed. 
• I just had to mention the input layers when I used Clip and the output name, and it gave back the perfect result when I ran the code
• I also saw the Python Code for “Split By Attribute” in the Analysis Toolbox, which was really cool. 

Chapter 4: 

• The 4th chapter is about learning how Python works and its syntax 
• This chapter was a bit easy for me because I’ve done Python before and only had to review some stuff to get started 
• I also came across Unicode (which helps you print out special characters that might not be in English) which I hadn’t before. 

Chapter 1: 

• The chapter mentions Python as a “scripting language” more than a programming language. Although I’ve seen this word around a lot in the CS Jargon, I haven’t really understood what it meant. The book mentions a clear distinction between the two. 
• The chapter also has a structure mentioned, as in a brief of what each chapter in the book entails, and that gives me a clear idea of what I’m going to be doing this semester. 
• It also mentions the advantages of using Python instead of just relying on the tools offered by ArcGIS Pro. 
• Was a very laid back introduction to  using Python in ArcGIS Pro, and gave me a gist of what I was getting myself into. 

Chapter 2: 

• I had trouble as soon as I started. The Python Command Line doesn’t work or show the same things as the textbook. I tried to get the Command Line(Prompt) and IDLE started but wasn’t able to. I got the following error, every time I tried to run: 
• Traceback (most recent call last):
•   File “<pyshell#4>”, line 1, in <module>
•     print(numpy._file_)
• AttributeError: ‘module’ object has no attribute ‘_file_’
• >>> 

• I think downloading PyCharm might work? Not sure 
• I got through it! The Python Window in ArcGIS Pro worked in the end and I did not need to download PyCharm as well. 
• The Python Window can be accessed by: 
  • (Assuming you have a map opened) → View Tab → Python Pane. (It should show up at the bottom) 
• The second chapter was an introduction to different types of Python IDEs and environments that can be used to go through with the book. Choosing the Python Window would be better in my opinion since there would be no need for extra downloads. 

I got through the first chapter in 20 minutes, however it took some time for the second one. But, I think now that I have figured this out, there should not be much trouble.

So excited to be in this course!! I decided against posting a picture of mine, since it’s already there somewhere on the 191 site, here’s another gorgeous picture: