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      • Table of Contents
      • How to Highlight and Take Notes
      • Acronyms
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      • Supported Coordinate Systems
      • Chapter One Title Page
      • Section One - Introduction
      • Section Two - What is GIS?
      • Section Three - Why Do We Need A GIS?
      • Section Four - Putting it all Together: An Example
      • Section Five - Uses of GIS
      • Section Six - History of GIS
      • Chapter Two Title Page
      • Section One - Introduction
      • Section Two - Geodesy
      • Section Three - Mathematically Measuring the Earth
      • Section Four: Latitude and Longitude - One Example of a Geographic Grid
      • Section Five: Geodetic Datums: Combining Reference Ellipsoids and Geoids
      • Section Six: Geographic Coordinate Systems
      • Section Seven: Projection Methods
      • Section Eight- Projected Coordinate Systems
      • Section Nine: Just a Few Extras
      • Chapter Three Title Page
      • Section One - Introduction
      • Section Two - Vector Data
      • Section Three - Raster Data
      • Section Four - Discrete and Continuous Data
      • Section Five - Data Tables
      • Section Six - Introduction to Attribute Tables
      • Chapter Four Title Page
      • Section One - Introduction
      • Section Two - Data Models
      • Section Three - Meet ArcGIS Pro Catalog View
      • Section Four - Meet ArcGIS Pro Maps and Layouts
      • Section Five - What Are Relational Databases and Geodatabases
      • Chapter Five Title Page
      • Section One - Introduction
      • Section Two - Attribute Tables: An Overview
      • Section Three - Attribute Tables Basics
      • Section Four: Selecting Data in ArcMap - The Basics of Making Selections
      • Section Five: Using Selected Data
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Section Three - Attribute Tables Basics

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  • Introduction to GIS
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  • Section Three - Attribute Tables Basics

In this section, we will take a minute to look at a few attribute table basics, such as the Table Option menu and the Field Header menu, field data types, and that we can complete arithmetic and statistics with the attribute table fields.  This is yet another section of the book where you're not being asked to memorize a series of software features, but you are stopping by some of the items in each menu to help introduce you to the topic. By looking at some of the features you'll be better prepared to interact with the software in a meaningful way.

The Table Options MenuThe Field Header MenuThe Table Action Buttons
The Table Options menu, found via the hamburger button in the upper right-corner of the attribute table, is one of two main menus found in the attribute table. In general, the Table Options menu contains actions which effect the whole table, such as opening the fields ( database electronic storage container with a top-down structure in which the items contained are related to each other and that relationship allows for the data to be quickly and efficiently queried and retrieved for use. for 'columns')  view, searching for and returning data in the entire table, and exporting the entire table for further data exploration in a software like Excel. Remember that the definition of a database electronic storage container with a top-down structure in which the items contained are related to each other and that relationship allows for the data to be quickly and efficiently queried and retrieved for use. was focused on the idea that the data can be returned quickly and efficiently? The applies here because ArcGIS is an RDMS relational database electronic storage container with a top-down structure in which the items contained are related to each other and that relationship allows for the data to be quickly and efficiently queried and retrieved for use. management system , capable of displaying spatial and non-spatial data Attributes related to a location but not describing its physical placement in space, such as information about a tree's age, type, and health. in a meaningful way. Attribute tables are database electronic storage container with a top-down structure in which the items contained are related to each other and that relationship allows for the data to be quickly and efficiently queried and retrieved for use. tables, and a whole lot of our job as a GIS Geographic Information Systems the software used to create, store, and manage spatial data, analyze spatial problems, and display the data in cartographic layouts   Geographic Information Sciences technician revolves around the ability to find and return records in the table. The Table Options menu leads us to that goal.

The Field Header menu, accessed by right clicking on a field name, is the second of two main menus found in the attribute table. In general, the Field Header menu contains actions which effect only that field. Between the Table Options menu and the Field Header menu, the latter is definitely the more used menu.

Tasks in this menu include:

  1. Sorting data
  2. Summarize the values in the fields (creates new output table)
  3. Explore Statistics (instant adding/statistics of the values in the field)/Visualize Statistics (create customizable charts)
  4. Calculate Field
  5. Calculate geometry (solves for the area of a polygon or the length of a polyline A GIS vector data in any sort of digital science or art, is simply denoting a type of graphical representation using straight lines to construct the outlines of objects geometry type which is made up of two or more vertices connected by straight lines. Often used to represent objects such as roads, river, and boundaries. )
  6. Delete the field

The Selection and Field Action buttons are shortcut buttons for the most common table actions. Just for convenience, all the the actions found in the Table Action buttons can be found in other menus.

These buttons can:

  1. Open Field View (via Add field)
  2. Calculate Field
  3. Open the Select by Attribute dialog box
  4. Switch the selected and unselected features
  5. Clear all the selected feature in this table only
  6. Zoom to selected feature(s)
  7. Delete selected feature(s)

5.3.2: Field Data Types

 All fields must have a defined type, either numbers or letters, which tell ArcGIS what actions can be associated with the field. For example, if you plan to add up the total area for all the features in a single feature class One of the two main types of vector data in any sort of digital science or art, is simply denoting a type of graphical representation using straight lines to construct the outlines of objects we learn in this class (there are more than two vector data in any sort of digital science or art, is simply denoting a type of graphical representation using straight lines to construct the outlines of objects types in GIS). Feature classes are each only one geometry type, either a point A GIS vector data in any sort of digital science or art, is simply denoting a type of graphical representation using straight lines to construct the outlines of objects geometry type which is made up of just one vertex pl. vertices One of a set of ordered x,y coordinate pairs that defines the shape of a line or polygon feature. , marking a single XY location in any given geographic or projected coordinate system. , a polyline A GIS vector data in any sort of digital science or art, is simply denoting a type of graphical representation using straight lines to construct the outlines of objects geometry type which is made up of two or more vertices connected by straight lines. Often used to represent objects such as roads, river, and boundaries. , or a polygon. Feature classes are stored in geodatabases and are most often used when data relationships are important. , ArcGIS is going to need those individual feature areas to be in a field which consists of decimal numbers. If the individual areas are stored in a field designed for letters only, the software will not know how to add them up, because you've told it, "Everything in this field is a letter, regardless if it comes from the alphabet, the number line, or a symbol map. Treat everything as though it is a letter and alphabetize them." Just like you haven't got a clue about how to solve for a+b+c+e+$+3+!+z, the software doesn't either, even if it sees letters shaped like numbers (since numbers stored in a text field are seen as letters). 
 
In summary, numbers go in number fields (integer or decimal) if you want them to be treated like numbers and be able to solve mathematical equations with them, alphanumeric characters go in text fields, if you want them treated like letters to be alphabetized, regardless of the shape of the character (letters, numbers, symbols), and dates/times go in date fields if you want them to be treated like dates (using date/time as a factor for analysis in the GIS Geographic Information Systems the software used to create, store, and manage spatial data Data that deals with location, such as lists of addresses, the footprint of a building, the boundaries of cities and counties, etc. , analyze spatial problems, and display the data in cartographic layouts   Geographic Information Sciences )
Figure 5.3: Field Data Types
  
Short IntegerWhole numbers; No decimal. Values must fall between -32,768 to 32,767
Long IntegerWhole numbers; No decimal. Values must fall between -2,147,483,648 to 2,147,483,647
FloatShort decimal numbers. Typically, the precision is 6 or less.
DoubleLong decimal numbers. Typically, the precision is 7 or more.
precision_scale-displayIf you select “Float” or “Double”, you are offered the option to designate a precision and scale. Precision, in this case, is to total number of numbers while scale is the count of numbers after the decimal.
Text
(AKA ‘String’)
Displays exactly what is entered in the box, regardless if it is a number, letter, or character. Defaults to limit of 255 characters.
DateSpecifically for dates. Using date over text for dates allows ArcGIS to have a temporal, or time, component. Display can be formatted in several ways.

5.3.3: Field Header Menu

In general, the field header menu has actions which affect only the field that the menu was launched from, such as performing arithmetic on the field, adding or changing values within the records of that field, or permanently deleting that field.

Sorting Table Values

The one item in the Field Header menu we use frequently which might seem like it belongs in the Table Options menu is the ability to sort the entire table by one single field. The resulting action is the entire table sorts, but the initiating action is housed in a menu that is supposed to control only the actions of one field. For example, if we want to examine population data by state, it might be easiest to first sort the entire table by the state name. You would use the sort option in the State Name field header menu, but it would be totally useless if the other fields - including the population field you are interested in - didn't sort as well. If that was the case, you might get the population of California in the same row as the name for the Rhode Island! Talk about confusing!

Much like when you are looking for a particular paper you wrote in Windows Explorer and you sort the contents of a folder by the file name (or term paper title in this case), being able to sort the contents of an attribute table is extremely important. Attribute tables default to sort by the FID (Feature Identifier), which is simply the order the features were added to the table, and likely has little other value in regards to the project at hand. If we add a States vector file we found online to a new ArcGIS Pro project and open the attribute table, we see the default order of features is based on the FID.
In this case, we see there are only 56 records (as noted by the count at the bottom of the attribute table window), so if we were to scroll through the list to find the state of “Colorado”, it wouldn’t be terribly challenging. After a quick scroll, we find Colorado has an FID of “26”.

While scrolling through 26 records wasn’t challenging, it is definitely the least efficient method we have to find records in an data table. Let’s sort the table alphabetically and ascending (seen above, in the same image where we scrolled to find that Colorado was feature number 26), which will make Colorado land in sixth place (based on the alphabet and not the FID).

To sort the entire table alphabetically, numerically, or chronologically by any one field, such as sorting the States table by the NAME field, right click on the field header to open the field header menu and choose either sort ascending (A-Z) or descending (Z-A). The result is seen to the right, where the NAME field is showing in alphabetical order and the FID is out of numerical order.

Records and Arithmetic

Determining total values in a field is another task which is asked of you quite often. Knowing the total miles of roads with attributes designating them as dirt, finding the average height of all the trees in a cruised stands, or determining the highest flow value of a series of measured streams. Like finding the state name Colorado, we can scroll through all the values and add them up with a calculator, or search until you find the highest value in a column. Now you know you could even sort the table by descending value for the stream flow field, and it will be the first record in the list.

Attribute tables make the process so much easier by having a built-in function for adding a field of values, finding the average, noting the maximum and minimum value in that column, and stating the standard deviation. By right-clicking on a field name to open the field header menu, you are presented with two options to find the statistics of a particular field - Explore Statistics and Summarize.

Figure 5.4: Statistics and Summarize Found in the Field Header Menu
The Field Header menu contains options for Explore Statistics (quick stats about the field) and Summarize (produce a new table of those stats). Each one is used in different ways - Explore Statistics for a quick summary, Summarize for an output table.

Both statistics and summarize perform almost the exact same task, with a few minor differences. For now, understand “Summarize” will create a new table which is saved to the computer and “Explore Statistics” will create a quick chart and list of values such as sum, mean, and maximum. Use Explore Statistics when you just need to find out value totals, averages, and value counts; use Summarize when you need to save the results for use later.

Figure 5.5: The Results of the Explore Statistics Tool
The Explore Statistics tool provides a quick look at how numeric data is distributed over a single field - in this case, the Population field.

ArcGIS groups all fields into one of six data types - short integer, long integer, double, float, text (string), and date, which we read about above. Each field type has a different set of available options which can be performed with it with the Explore Statistics and Summarize tools, such as adding integers or creating a time-lapse effect with date. The text field, which is most often used for nominal values, allows you to enter any character in it without creating problems with the database electronic storage container with a top-down structure in which the items contained are related to each other and that relationship allows for the data to be quickly and efficiently queried and retrieved for use. . This means when you put numbers into a text type box, they are no longer seen as numbers with which arithmetic can be performed, but rather an alphanumeric character representing a numeric value. To ArcGIS, the numeric character "3" entered into a text box is no different than writing out the word “three”. They are both characters representing a count of three items.

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