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.