| SAS/GRAPH Software: Reference |
A drill-down graph links designated areas or hot zones of a graph to target output, such as other graphs or reports.
The target output can be in a different location on the same Web page, or
it can be on a different Web page. If the target output contains another graph,
that graph can also have hot zones that link to additional targets. In this
way, you can establish a series of links that drill down to more and more
detailed information.
Drill-down on a Bar Chart
shows a bar chart with three bars. Assume that the bars represent a company's
regional sales, and that the third bar represents the western region. If the
chart is a drill-down graph, with each bar linking to a report on the corresponding
region's sales, then selecting the third bar drills down to a report on sales
for the western region.
Drill-down on a Bar Chart
![[IMAGE]](./images/01215130.gif)
The hot zones in a drill-down graph can be the graphic
areas (for example, the bars in a bar chart or slices in a pie chart) or the
pattern boxes that identify legend entries. SAS/GRAPH defines the hot zones
for you, based on the specifications you make on the graphics procedure used
to produce the graph. You use the HTML= option to make hot zones in the graphic
areas, and the HTML_LEGEND= option to make hot zones in the legend. You provide
the link information by storing the paths to target output in a special HTML
variable, which is usually created in the data set that is used to generate
the graph.
Only procedures that support the IMAGEMAP= option, or
the HTML= or HTML_LEGEND= options, can be used for drill-down graphs, although
you can also generate drill-down graphs using the Data Step Graphics Interface
(DSGI). Procedures that Support Drill-down Graphs
lists those procedures and shows where the HTML variable that stores the linking
information is specified for each of them.
You can generate a drill-down graph using the SAS/GRAPH
Web drivers or using ODS. The approach to use depends on your Web-page design.
To link to individual graphs, it is easiest to use the
Web drivers to generate the drill-down graphs. The Web drivers create all
the files you need and require the fewest specifications in your SAS code.
For an example, see Example 3: Using a Web Driver to Generate a Drill-down Graph.
The Web drivers do not assign anchor names to the output
they generate. Thus, they are not useful for linking to multiple pieces of
output that are stored or referenced in one HTML file.
To link to both graphics and non-graphics output, or
to link to multiple graphs that are stored or referenced in a single file,
it is easiest to use ODS to generate the drill-down graphs. For an example,
see Example 4: Using ODS to Generate a Drill-down Graph.
Also, if you want to design the attributes of your Web page, ODS lets you
use style definitions. For example, you can set the fonts and color for text.
For information on style sheets, see The Complete Guide to the SAS Output Delivery System.
To generate a drill-down graph with ODS, your main responsibility
is to create the required HTML variables and assign to those variables the
appropriate linking information in the form "URL#anchor-name".
ODS always assigns anchor names to the output it generates;
that way, the output can be used as the target to a link, no matter where
the output is located. By default, ODS assigns the anchor name IDX to the
first piece of output that is generated after the HTML destination is opened,
IDX1 to the second, IDX2 to the third, and so on, incrementing the IDX number
consecutively for each piece of output generated. It does not matter whether
the output is all written to the same HTML file or to separate HTML files.
The default system for assigning anchor names always starts with IDX for the
first piece of output that is generated after the HTML destination is opened
and increments that name (IDX1, IDX2, ...) for each piece of output that is
written until the HTML destination is closed. If the HTML destination is opened
again during the current SAS session, the default naming scheme starts over
again, beginning with IDX.
The value that you assign to an HTML variable must be
the HREF value that is needed for the HTML link. Therefore, to define a link
for a drill-down graph, you must know what URL is needed to access the target
output, and what anchor name ODS assigns to that output.
While planning your Web page, you have to decide whether
to let ODS assign default anchor names, or whether to control anchor names
yourself using the ODS HTML statement's ANCHOR= option. Generally, the default
anchor names will suffice for simple drill-down graphs or when each link target
contains only a single piece of output in its own HTML file. You may want
to control anchor names when you use multiple procedures to generate the target
output because it will be easier to keep track of the anchor names. You may
also want to control anchor names when you open a body file to append output
to it; in this case, controlling anchor names prevents ODS from using the
same default anchor names as were used when the file was first created.
To get complete control over Web page design, you can
customize a Web page for use with a drill-down graph by writing your own HTML
files, letting SAS/GRAPH generate the drill-down graph. To customize a Web
page, you must know how to
However, you do not have to know how to create an image map,
because SAS/GRAPH does that for you. For details, see Customizing Web Pages for Drill-down Graphs. For an example, see
Example 5: Customizing a Web Page with a Drill-Down Graph.
Generally, to create a drill-down graph, you provide
the link information needed to connect the graph to its related output. Your
SAS program must do the following:
-
create an HTML variable to hold HTML link locations.
Typically, for each drill-down level, you create one HTML variable to store
the links for the graphic areas, and a separate variable to store links for
the legend values. For example, to implement the graph in Drill-down on a Bar Chart, you need only one HTML
variable for the bars in the chart.
-
assign values to the HTML variable(s). These values
are the link locations that connect the graph to its target output.
-
run a SAS/GRAPH procedure to create the drill-down
graph(s). This procedure must use an HTML= option, an HTML_LEGEND= option,
or both, to associate the HTML variable(s) with the graph. Or, if the drill-down
capability is being implemented from an Annotate data set, the Annotate data
set's HTML variable must specify the link locations (for an example, see Using Annotate Graphics in a Drill-down Graph).
If you are using the
HTML or WEBFRAME device drivers,
or if you are writing your own HTML files, you must also use the IMAGEMAP=
option to create a data set that can be used to generate an image map for
the drill-down capability.
-
run the procedures that create the target output.
The target output must be directed to the locations identified by the HTML
variable.
Because an HTML variable stores the HTML link locations
for target output, you must understand HTML links in order to assign values
to it. You should also know what an image map is, because SAS/GRAPH uses image
maps to attach HTML links to drill-down graphs (see Image Maps in Drill-down Graphs).
In HTML files, links are specified as HREF= attributes
on tags that support linking. The HREF= value must point to the location of
the link target, which is identified by a URL and an anchor
name in the form
HREF="URL#anchor-name"
In
Drill-down on a Bar Chart,
the bars represent regional sales, and the third bar represents the western
region. If the third bar drills down to a report, and if that report is stored
in your file system at the top of a file named west.htm, then the following
HREF points to the report:
HREF="west.htm"
Here, only a file name is given. The file west.htm is,
therefore, assumed to be in the same storage location as the HTML file where
the link is initiated. The anchor name is omitted because the report is at
the top of file west.htm, so the anchor name isn't needed. However, if the
report is not at the top of the file, the HREF must specify the anchor name.
In an HTML file, anchor names are assigned on the NAME=
attribute of an <A> (anchor) tag. In the following example, the anchor
name west is assigned to the table that follows it:
<A NAME="west" ></A>
<P>
<TABLE><TR><TD>
Western Sales
</TD></TR></TABLE>
If the report is stored in a file named reports.htm,
as is the case for Drill-down on a Bar Chart,
then the following HREF points to the report at the west location:
HREF="reports.htm#west"
More HREF= values are shown in Assigning Values to HTML Variables.
For information on how ODS
constructs HTML links and
references, see How ODS Constructs Links and References.
An image map defines the graphic areas that you can
select to link to other locations. For example, in Links in Drill-down Graphs, the third bar in the image barchart.gif
links to a report that is stored in the file reports.htm, located at anchor
name west. To implement the drill-down capability, an image map must define
that third bar as a hot zone by identifying its coordinates and linking those
coordinates to the report's location.
Links in Drill-down Graphs
![[IMAGE]](./images/01215131.gif)
In an HTML file, an image map is defined within <MAP>
tags, which are used to encompass <AREA> tags that define the areas that
will serve as hot zones for the links. Each <AREA> tag has the following
attributes:
For example, the chart shown in Links in Drill-down Graphs is stored in
file barchart.gif,
which is referenced in an HTML file named sales.htm. To give barchart.gif
drill-down capability, sales.htm must contain HTML tags to define an image
map that is assigned to barchart.gif. The image map must have <AREA> tags
that identify the coordinates of each of the three bars in the chart, and
that define a link target for each bar. The image map is assigned to the graph
on the USEMAP attribute of the <IMG> tag that references the graph's GIF
file.
In the following image map, the HREF attributes link
each bar to an HTML file named reports.htm. The target output for each bar
is directed to a different anchor location; the anchor names for the target
output are central, south, and west. File reports.htm is in the same location
as the file that contains the image map, because no other location is identified.
<MAP NAME="BARCHART">
<AREA SHAPE=RECT COORDS="424, 143, 470, 256"
href="reports.htm#central">
<AREA SHAPE=RECT COORDS="366, 175, 412, 256"
href="reports.htm#south">
<AREA SHAPE=RECT COORDS="308, 106, 354, 256"
href="reports.htm#west">
</MAP>
<P>
<IMG SRC="barchart.gif" USEMAP="#BARCHART">
When you select a bar in the graph, the browser uses
the image map to find the correct report to link to, as shown in Links in Drill-down Graphs.
The image map must be defined in the same HTML file
as the <IMG> tag that references the graph that will use that map. However,
the map can be located anywhere in the file. For example, the image map can
be at the very end of the HTML file, even though the <IMG> tag that uses
the map is at the top of the HTML file.
SAS/GRAPH automatically generates image maps; you do
not have to know how to create an image map, and you do not have to supply
values for its SHAPE or COORDS attributes. However, you must supply HREF values
that identify the locations of the target output. You provide these values
by assigning them to an HTML variable and specifying that variable on the
graphics procedure that produces the drill-down graph.
HTML variables are used with ODS to create graphs with
drill-down capability. The HTML variable is a character variable that stores
the HTML link locations for target output. You must create the HTML variables
by adding them to the data set that is used to produce the drill-down graph.
Typically you create the HTML variables in a DATA step.
The following code fragment creates the HTML variable
RPT and assigns it a length of 40 characters so that it can store a long string:
/* create data set REGSALES */
data regsales;
input Region State Sales;
/* create the HTML variable */
length rpt $40
Drill-down graphs use image maps to define hot zones
in the graph and to identify each hot zone's link target. A hot zone is defined
on an <AREA> tag, and the zone's link target is specified as a value on
the <AREA> tag's HREF attribute (see Image Maps in Drill-down Graphs). SAS/GRAPH automatically creates the image
maps for you, but you must provide the HREF values by first assigning those
values to an HTML variable and then specifying that variable on an HTML= or
HTML_LEGEND= option on the procedure that produces the drill-down graph.
The HTML variable must be a character variable, so the
value you assign to it must be a string. Always begin the string with href= followed by the link location in the form "URL#anchor-name". The following code
assigns a valid value to an HTML variable
named RPT:
RPT='href="reports.htm#west"';
Note:
To form valid HTML, the URL and anchor name must be
enclosed in double quotation marks, as shown in the example. ![[cautend]](../common/images/cautend.gif)
Using the RPT variable's value in an image map, SAS/GRAPH
can build an <AREA> tag that resembles this:
<AREA SHAPE="RECT" COORDS="424,143,470,256"
href="reports.htm#west">
To specify an HREF value correctly, you must know in
advance the correct location to specify for the link target. This requires
you to plan your SAS program. You need to decide such issues as
Valid Forms for the HTML Variable's Values
shows the forms you can use to assign values to an HTML variable.
Typically a drill-down graph has multiple hot zones,
each of which links to different output. This means your HTML variable needs
different values, based on the criteria used to produce the graph. For example,
if the bars in a bar graph represent sales regions, then the values of the
HTML variable will be based on those sales regions.
To assign values to the HTML variable, you can include
the variable in the DATA step's INPUT statement and specify the values in
the DATALINES statement. Or you can specify the values programmatically, perhaps
in a conditional block, such as an IF/THEN statement.
In Links in Drill-down Graphs,
assume that the three bars represent regional sales for a company's central,
southern, and western regions.
Links in Drill-down Graphs
To link each bar to a report on that region's sales
figures, you need one HTML variable to store the HREF links. The HTML variable
needs to point to a different location for each of the three regions. If you
decide to write all the reports to a file named reports.htm, which your users
will access through your file system, and if the reports have anchor names
central, south, and west, you might write a DATA step that resembles the following:
/* create data set REGSALES */
data regsales;
length Region State $ 8;
format Sales dollar8.;
input Region State Sales;
length rpt $40; /* the HTML variable */
/* assign HREF values to HTML variable */
if Region='Central' then
rpt='href="reports.htm#central"';
else if Region='South' then
rpt='href="reports.htm#south"';
else if Region='West' then
rpt='href="reports.htm#west"';
datalines;
West CA 13636
West OR 18988
West WA 14523
Central IL 18038
Central IN 13611
Central OH 11084
Central MI 19660
South FL 14541
South GA 19022
;
Values in the REGSALES Data Set
shows the values in the data set REGALES.
Values in the REGSALES Data Set
![[IMAGE]](./images/01215132.gif)
To use the HTML variable to create hot zones on the
bars of the drill-down chart, you must specify it in the HTML= option of the
graphics procedure that produces the graph.
See
also:
Copyright © 1999 by SAS Institute Inc., Cary, NC, USA. All rights reserved.
