The GCHART procedure, when
used with SYMBOL or PATTERN definitions, assigns the symbols or patterns
in order to each BY group. For example, if the BY variable REGION
has four values—
East
,
North
,
South
,
and
West
—the patterns are assigned
to the BY-groups in this order:
-
PATTERN1 is assigned to East.
-
PATTERN2 is assigned to North.
-
PATTERN3 is assigned to South.
-
PATTERN4 is assigned to West..
If you create sets of
graphs from several data sets containing the variable REGION, and
if you want the same pattern assigned to the same region each time,
you must make sure that REGION always has the same four values. Otherwise,
the patterns might not be the same across graphs. For example, if
the value
North
is missing from the data,
the patterns are assigned as follows:
-
PATTERN1 is assigned to East.
-
PATTERN2 is assigned to South.
-
PATTERN3 is assigned to West..
In this case,
South
is
assigned pattern 2 instead of pattern 3 and
West
is
assigned pattern 3 instead of pattern 4. To avoid this, include the
value
North
for the variable REGION, but
assign it a missing value for all other variables.