Vigraph FAQ

                         Document #: US-13265,EN
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Major subject: analysis    Minor subjects: tech_notes

Keywords: 

Abstract:
VIGRAPH: Commonly Asked Questions and Answers - Equivalent 
to Release 6 Technical Note #25 or note #81 in Release 5.


Expert note:
VIGRAPH:  Commonly Asked Questions and Answers 
==============================================

Overview
--------
The following several pages will assist you in more fully realizing  the
benefits of VIGRAPH.  Covered in a question and answer format are illus-
trations on graphic presentation and data organization methods  suitable
for the best use of  VIGRAPH.

o	How do you get hatch patterns to appear on your graph?
o	How do you get more than one line or bar color or marktype on a graph?
o	How do you produce a histogram (frequency bar chart) using VIGRAPH?


QUESTION 1
----------
How do you get hatch patterns to appear on your graph?

ANSWER 1
--------
The profile screen allows you to change the presentation  level  of  the
plot.   Presentation  level 4 provides fully detailed colored hatch pat-
terns in place of solid colors (level 5).  Presentation level 3  present
the  hatch  patterns  in  monochrome.  Here is an example of the profile
screen.  Note that the presentation level can be changed  in  4  places:
main layout, edit, layering and  plotter.

EDITOR OPTIONS

       Presentation levels:
             main layout: 3  edit: 2  layering: 1

       Error explanations (y/n):     y
       Confirmation checks (y/n):    y
       Hold redraw on edit (y/n):    n

       Truncation length for data: 0    Font comparison character: g

PLOTTER DATA

       Plot location:                                 Empty location indicates
                                                      plot directly to terminal.

       Device type:   tek4105c      Empty type defaults to terminal type.

       Presentation level: 4
________________________________________________________________________________


QUESTION 2
----------
How do you get more than one line or bar color or marktype on a graph?

ANSWER 2
--------
You have to organize your data so that the values for the legend are  in
a column, and that value is repeated for the appropriate x and y values.
For example, if you want to plot sales by month for several      depart-
ments,  where  the  bar  for  each department is a different color, your
table should look like this:

        |sales            |month |dept  |
        |-------------------------------|
        |           $20.00|Jan   |Shoe  |
        |           $13.00|Feb   |Shoe  |
        |           $35.00|Mar   |Shoe  |
        |           $15.00|Jan   |Toy   |
        |           $17.00|Feb   |Toy   |
        |           $21.00|Mar   |Toy   |
        |           $25.00|Jan   |Coat  |
        |           $18.00|Feb   |Coat  |
        |           $28.00|Mar   |Coat  |
        |-------------------------------|

The dept column will provide the legend labels and  will  be  associated
with  a  color  or pattern for bar charts, line type for line graphs, or
mark types for scatter plots.

        VIGRAPH - Data Mapping Specification

                                                           Available columns
                                                        +------------+---------+
                                                        |Column Name |Format   |
                                                        |------------+---------|
        Table or view to graph: mon_sales               |sales       |money    |
                                                        |month       |c3       |
                                                        |dept        |c5       |
                Horizontal axis (X): month              |            |         |
                                                        |            |         |
                  Vertical axis (Y): sales              |            |         |
                                                        |            |         |
         Optional series column (Z): dept               |            |         |
                                                        |            |         |
                               Sort: no                 +------------+---------+

Be sure to change the sort from the default of yes to no.  Otherwise the
months  would  come out in sorted order.  It will sometimes be necessary
to include an extra column in your table to preserve  the  correct  sort
order.   Please  refer to Chapter 4 in the VIGRAPH User's Guide for more
information on data preparation.


QUESTION 3
----------
How do you produce a histogram  (frequency  bar  chart)  using  VIGRAPH?

Given a table that contains a column (A) that had some data values in it
like this:

                table1          How do you get a plot that looks like this:

                |a         |
                |----------|  4-|          _____
                |     1.543|    |          |   |
                |     2.632|  3-|   _____  |   |         _____
                |     4.113|    |   |   |  |   |         |   |
                |     5.437|  2-|   |   |  |   |  _____  |   |
                |     6.002|    |   |   |  |   |  |   |  |   |
                |     7.100|  1-|   |   |  |   |  |   |  |   |
                |     9.030|    |   |   |  |   |  |   |  |   |
                |    10.000|    --------------------------------------
                |    14.550|         0-5    5-10  10-15  15-20
                |    15.980|
                |    18.220|
                |    19.104|    Where the X axis is a range of buckets for
                |----------|    column A values and the Y axis is the frequency
                                of occurrences of X.

ANSWER 3
--------
You can produce a histogram with a few simple steps.

        1.  Create a temporary table with the following definition:

        In SQL:
                CREATE TABLE temp (seq integer2,
                                   bucket vchar(6),
                                   b_begin float4,
                                   b_end float4);
        In QUEL:
                CREATE temp (seq=i2,bucket=text(6),b_begin=f4,b_end=f4)

        2.  Using QBF, or the query language in the terminal monitor,
        populate the temporary table with bucket ranges.  For example:

        temp table

        |seq   |bucket|b_begin   |b_end     |
        |-----------------------------------|
        |     1|0-5   |     0.000|     4.990|
        |     2|5-10  |     5.000|     9.990|
        |     3|10-15 |    10.000|    14.990|
        |     4|15-20 |    15.000|    19.990|
        |-----------------------------------|

        The sequence column(seq) is needed so that the buckets come out in
        the order specified rather than in sorted order.

        3.  Create a view with the following definition:

        In SQL:
                CREATE VIEW histogram (seq,xcol,ycol)
                        AS SELECT  temp.seq,
                                   temp.bucket,
                                   count(table1.a)
                        FROM temp,table1
                        WHERE table1.a BETWEEN temp.b_begin and temp.b_end
                        GROUP BY temp.seq,temp.bucket;

        In QUEL:
                DEFINE VIEW histogram (
                        temp.seq,
                        xcol=temp.bucket,
                        ycol=count(table1.A BY temp.bucket
                                WHERE table1.A >=temp.b_begin
                                  AND table1.A <= temp.b_end))

        The resulting view contains the following data and can be used as
        the basis for your graph:

        |seq   |xcol  |ycol         |
        |---------------------------|
        |     1|0-5   |            3|
        |     2|5-10  |            4|
        |     3|10-15 |            2|
        |     4|15-20 |            3|
        |---------------------------|

4.  On the MapData screen in VIGRAPH, make sure you say no to sorting, because
    if you leave the default of yes, the values in the xcol will be sorted.
    Here is an example of a MapData screen:

        VIGRAPH - Data Mapping Specification
                                                           Available columns
                                                        +------------+---------+
                                                        |Column Name |Format   |
                                                        |------------+---------|
      Table or view to graph: histogram                 |seq         |i1       |
                                                        |xcol        |text(6)  |
                                                        |ycol        |i4       |
                Horizontal axis (X): xcol               |            |         |
                                                        |            |         |
                  Vertical axis (Y): ycol               |            |         |
                                                        |            |         |
         Optional series column (Z):                    |            |         |
                                                        |            |         |
                               Sort: no                 +------------+---------+



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