You can also create points by matching values in a table against a reference feature class. The point events created from the table behave just like a feature class and can be symbolized and labeled using attributes in the table. Below is an example of how a simple table of coordinates and other data can be converted to point events. Perhaps the simplest method of doing this is by using the XY Event Layer tool to make a layer from a table that contains an x- and a y-coordinate field. Making features from tablesĪnother common technique is to create spatial information from tabular data. Also, if a key value is misspelled, has variant spellings, or contains a typographic error or extra characters (for example, a trailing space character), the records with unmatched keys will not be joined. To work around this, you can create a new field in one of the tables that matches the data type in the other table, then calculate the values from the nonmatching field into the new, matching field. If one field is of numeric type and the other is text, it will not be possible to join using those fields. When you join data from different sources, it is important that the data types and values of the key fields match exactly. It has name and FIPS code attributes as well, so either could be used to join it to the county features.Īfter the harvest data is joined to the county features, you can use the fields from the harvest table to symbolize, label, or select the county features. This stand-alone table contains information on the soybean harvest for each Iowa county. This feature class of Iowa counties has name and FIPS code attributes that could be used as key fields for a table join. This requires that the table and the geographic features share a key field, such as a name or an ID code.īelow is an example of how GIS features can be given additional attributes by joining data from another table. One common technique is to join a table of data, such as demographic or medical statistics, to a set of geographic features for visualization. Creating GIS data from tables Joining tables Often several geoprocessing steps modify and combine sets of data, resulting in a feature class with many attributes derived from other data, which can be selected or summarized to produce tabular results. Some analyses require that GIS data be extracted as tables for another application, or tabular data from another application may become an input to the GIS. When constructing a database or performing analysis, much of your time will be spent managing tables: adding and calculating new attributes, copying tables or their rows from one location to another, converting tables containing text strings of coordinate values into features, relating one table to another, or calculating summary statistics. For example, feature classes are tables with a shape attribute (an attribute in a table is also termed a field or column), rasters can be viewed as tables of attributes, and most GIS databases have stand-alone tables containing attributes that can be related to other tables by a common attribute. Almost all GIS data is stored or represented as a simple database table.
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