Node:Test print-graph, Next:, Previous:The final version, Up:Print Whole Graph


C.4.1 Testing print-graph

We can test the print-graph function with a short list of numbers:

  1. Install the final versions of Y-axis-column, graph-body-print, and print-graph (in addition to the rest of the code.)
  2. Copy the following expression: 
    (print-graph '(3 2 5 6 7 5 3 4 6 4 3 2 1))
  3. Switch to the *scratch* buffer and place the cursor where you want the axis labels to start.
  4. Type M-: (eval-expression).
  5. Yank the test expression into the minibuffer with C-y (yank).
  6. Press <RET> to evaluate the expression.

Emacs will print a graph that looks like this: 

10 -


         *
        **   *
 5 -   ****  *
       **** ***
     * *********
     ************
 1 - *************

     |   |    |    |
     1   5   10   15

On the other hand, if you pass print-graph a vertical-step value of 2, by evaluating this expression: 

(print-graph '(3 2 5 6 7 5 3 4 6 4 3 2 1) 2)

The graph looks like this: 

20 -


         *
        **   *
10 -   ****  *
       **** ***
     * *********
     ************
 2 - *************

     |   |    |    |
     1   5   10   15

(A question: is the `2' on the bottom of the vertical axis a bug or a feature? If you think it is a bug, and should be a `1' instead, (or even a `0'), you can modify the sources.)