SINGLE MAP ANALYSIS

SINGLE MAP ANALYSIS

Summarization of an attribute table
Statistics for selected features. The Selection Statistic dialog for sum, count, mean, maximum, standard deviation, range and variance. ArcGis will perform calculate on a selected records using the Query Builder.
Step-by-step
The Attribute table that contains the field to be analyzed, right-click on the field and select Statistics (Sum, minimum, standard deviation...

Spatial Relationship (distance, containment, intersection, and adjacency).
To Select by Location, you must specify the selection method, a selection layer, a spatial relationship, a reference layer and distance buffer. This is neighborhood analysis. One type of neighborhood analysis selects only adjacent features. Another type selects neighbors based on a distance to nearby features. The third type identifies features based on attribute values of adjacent features.

Buffering иCpoint, line and polygon features buffered by expanding distance from a feature. Buffering always creates a polygon feature type and is the basis for proximity analysis. The Buffer Wizard helps you create buffers around the selected features of a feature theme. To define the better distance, there are 3 ways:
- at a specified distance allows you to set a distance that is applied to all selected features in the active theme
- at a distance from an attribute field allows you to set the buffer distance based on the value in an attribute field
- as multiple rings allows you to create multiple rings at a defined increment
SPATIAL RELATIONSHIP FOR SELECTED BY LOCATION within selected features.
Spatial Query and Analysis
Open Attribute Table-Options-Clear Selection
Open Attribute Table-Options- Select by Attributes and do Query. Do new layer.
Activy Selection- Select by location. Lection Clear the selection set. Clear the Buffer.

GIS Cookbook: Getting Started - Performing a Spatial Query
Keywords: query, spatial, topological, select by location
Category: Starters
Software: ArcGIS 8/9.x

Problem: You want to select map features based on their spatial relationship with other map features.

Description: One capability that distinguishes GIS software from simple drawing packages is the ability to explore the spatial relationships between map features in different layers. These relationships (often referred to as topological relationships after the branch of geometry called topology) include connectivity, adjacency, and containment. GIS software enables researchers to ask questions like:



Which roads are connected to Interstate 80?

Which census tracts are adjacent to this industrial park?

How far is the nearest bus stop from each of my study subjects?

Which schools are contained within this Metropolitan Statistical Area?

Etc.




Methodology:
Many of these types of questions can be answered by building a spatial query using the Select By Location dialog. Assuming you have ArcMap open and have added all of the desired data layers, you can build a spatial query as follows:

1. Click on Selection > Select By Location.

Setting the options in the Select By Location dialog can be approached by constructing a sentence that describes the query, beginning at the top with the words, I want to:.

2. The first option is the selection method. In most instances, the default option of select features from is the most appropriate. See Note #1 for more information on selection methods.

3. The next step is to specify which layer(s) contain the features youбпd like to select by choosing from the list under the words the following layer(s).

4. Next comes the choice of an appropriate spatial relationship from the drop-down list under the word that:. See Figure 1 for a list of available relationships
5. To complete the sentence, you must choose the other layer participating in the relationship by selecting from the list under the words the features in this layer:.

6. Click Apply to execute the query. Figure 2 shows an example of a point-in-polygon selection

7. Optionally, you may want to specify that only the selected features in the query layer (Western States in this example) be used to find matching features in the target layer. This can be done by clicking the Use selected features checkbox as shown in Figure 3.
8. Buffering the features in the query layer is another optional setting. When the are within a distance of relationship is selected, this checkbox is automatically checked. Upon selecting this option, the next step is to enter the desired buffer distance. Figure 4 shows an example of selecting cities within 100 miles of the Nevada border.

Notes:
1. The first drop-down list in the Select By Location dialog provides a list of selection methods. It defaults to Select features from, which means that if there are already some features selected, that selection set will be wiped out. Other choices include: Add to the currently selected features in, Remove from the currently selected features in, and Select from the currently selected features in. These other selection methods may be used to evaluate multiple spatial queries one at a time.

2. If you open the layerбпs attribute table, note that the tabular records associated with the selected map features are also shown in the selection color.

3. Besides simply seeing which map features meet some criteria, creating a selection set is an important step in performing a number of other GIS functions. These include:



Using the selection set for further analysis (such as buffering the selected features)

Using the selection set to select features in another layer

Editing the selection set (either the geometries of the features or their attributes)

Creating a new layer from the subset

Calculating summary statistics for the selected features

Buffer Wizard:
The Index view provides a list of all the tools in alphabetical order. Typing in the name of the tool you are interested in jumps you to the word in the Index as you type it. Clicking on the "Locate" button brings you to the tool in the Favorites view. Double clicking on the tool name in the list opens the tool. This is a quick way to get at a tool if you know the name.
The Search view lets you type in a keyword that may turn up in several different tools. As in the Index, double clicking on a result opens the tool, and clicking on "Locate" brings you to the tool''s location in the Favorites view.
As can be seen here, there a couple of options for buffering that you may not have found in the Favorites view.

All three of these methods allow locating and opening one of the many tools in ArcToolbox. Explaining how all the tools work is beyond the scope of this article, but they all look very similar, and getting familiar with one will get you a long way towards getting comfortable with the others. So, let''s take a look at the tool in question, Buffer

This is pretty much how all the tools look. It is a basic input form, with text boxes, combo boxes, radio buttons, and list boxes, etc. There is a help window on the right side that tells you what the tool will do and how to use it, if you do not know what you''re doing. If you are already comfortable using a tool, the help window can be hidden. The help window changes depending on which input control is active. For example, no control is active now, so an overview of the Buffer tool is displayed in the help window. When I click in the "Input Features" box to start choosing the layer I''m going to buffer, the help window changes:
Clicking on OK runs the tool, and adds your newly created layer to ArcMap

How to select features by attributes
1. Click Selection on the Main menu and click Select By Attributes.
2. Click the Layer drop-down arrow and click the layer containing the features you want to select.
3. Click the Method drop-down arrow and click a selection method.
4. Double-click a field to add the field name to the expression box.
If you want to sort the list of fields or see the fields by their aliases, click the small button on the top right of the fields list.
5. Click an operator to add it to the expression.
6. Click Get Unique Values to see the values for the selected field.
Double-click a value to add it to the expression.
7. Click the Verify button to see if you are using proper syntax or if the criteria you''ve entered will select any features.
8. Click Apply.
The status bar at the bottom of the ArcMap window tells you how many features are selected.
9. Use the Clear button to empty the expression box.
10. Use the Save and Load buttons respectively to save your current query as a file or load an existing one.
The files used to save the queries have a .exp extension but can be edited with any text editor. Only the content of the expression box is saved in the file, not the complete expression.
11. Click Close when you are finished selecting features


Keywords: query, attribute, select, tabular, SQL
Category: Starters
Software: ArcGIS 8/9.x

Problem: You want to select map features that have certain tabular attributes.

Description: One of the most common functions in a GIS is the ability to ask the software to display all of the geographic features that meet some criteria. These criteria may be based on information stored in a layerбпs attribute table (an attribute query) or they may involve desired spatial relationships between features in different geographic data layers (a spatial query). This recipe will focus on building an attribute query.


Methodology:- http://www.csiss.org/cookbook/starter/44
Assuming you have ArcMap open and have added all of the desired data layers, you can build an attribute query as follows:

1. Click on Selection > Select By Attributes.

2. In the Select By Attributes dialog, be sure to select the Layer whose attribute table youбпd like to query. Upon selecting a layer, you should see a list of its Fields (or columns) appear on the left side of the dialog.

3. In the Fields list, double-click on the desired field. Note that the name of the field is added to the large text box in the bottom half of the window.

4. Next, click on one of the logical operators in the middle of the dialog (such as =, >, б▌, etc.).

5. The last step in building the query expression is to enter a value that is appropriate for the field and that defines your selection criteria when combined with the chosen logical operator. You may place the cursor at the end of the expression and manually type the desired value, or you may click the Get Unique Values button to see a list of the unique values within the chosen field and then double-click on one of the values listed to insert it at the end of the expression.

6. When youбпve finished building the query expression, click the Apply button. ArcMap will highlight the features that meet your criteria in the selection color (cyan, by default).

Notes:
1. One of the options in the Select By Attributes dialog is Method. This defaults to Create a new selection, which means that if there are already some features selected, that selection set will be wiped out. Other choices include: Add to current selection, Remove from current selection, and Select from current selection. These other selection methods may be used to evaluate multiple attribute criteria one at a time.

2. Another way to evaluate multiple selection criteria is to use the logical operators And and Or. For example, if you wanted to select states with a population density over 75 and at least 50000 farms, after entering the value 75 you could click the And operator, then begin the three-step process (field-operator-value) again to enter the second part of the compound expression.

3. If you open the layerбпs attribute table, note that the tabular records associated with the selected map features are also shown in the selection color. In fact, it is possible to invoke this same Select By Attibutes dialog by clicking on the Options button in the lower right of an open attribute table window.

4. Besides simply seeing which map features meet some criteria, creating a selection set is an important step in performing a number of other GIS functions. These include:

o Using the selection set for further analysis (such as buffering the selected features)
o Using the selection set to select features in another layer
o Editing the selection set (either the geometries of the features or their attributes)
o Creating a new layer from the subset
o Calculating summary statistics for the selected features
o and more...


5. Using the Save and Load buttons in the Select By Attributes dialog, it is possible to store query expressions on disk and re-load them at a later time.
Pitfalls:
o New users frequently encounter syntax errors when using the Select By Attributes dialog. Remember to double-click on the items in the Fields and Unique Values list boxes and single-click on the logical operator buttons. If you''re unable to pinpoint the error in your expression, it may be easiest to click the Clear button and start again
Tutorials
Goal: In this exercise you will learn to perform a spatial analysis operation by selecting features that, for example, are within a distance of, or have their center in that feature.
Step 1. Add the "Majrivr.shp" and the "Oagwells.shp" to the View.
Step 2. Right Click in the map view and scroll down to Properties to receive the Data Frame Properties dialog box. Click the General tab and change the Map Units and Display Units to Meters. Then click OK.
Step 3. From the Selection pull-down menu, choose Select By Location. The Select By Location dialog box displays
Step 4. Fill out the Select By Location Dialog box. We want to select features from oagwells that are within a distance of 500 meters from majrivrs. Then Click Apply.
Note: Notice that your choices form this sentence: Select features from"Oagwells.shp" that are within the selected distance of "Majorivr.shp". The specified selection distance is 500 meters." Therefore, points in the Oagwells.shp will be highlighted if they are within 500 meters of a major river.
Step 5.Use the Zoom in tool to a selected Oil and Gas well that is highlighted in light blue.
Step 6.Use the Measure tool , and measure one of the Wells to the river. Notice the Segment Length at the bottom of your view.
Step 7.Close ArcGIS or continue with the next exercise.


DUAL-MAP ANALYSIS USING GEOPROCESSING

The SELECT BY LOCATION used for relationship. A limitation of that type of analysis is that precise statistical calculation cannot be made on the amount of overlap of various features. The feature themes will need to be overplayed to create new feature themes with the geometry changed by intersection or clipping themes. Geoprocessing tools: dissolve, merge, clip, in

Using Select By Location
Keywords: query, spatial, topological, select by location
Buffer Wizard
Select by Attributes
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