Next: Testing print-graph, Up: Printing the Whole Graph [Contents][Index]
The final version is different from what we planned in two ways: first, it contains additional values calculated once in the varlist; second, it carries an option to specify the labels’ increment per row. This latter feature turns out to be essential; otherwise, a graph may have more rows than fit on a display or on a sheet of paper.
This new feature requires a change to the Y-axis-column
function, to add vertical-step to it. The function looks like
this:
;;; Final version.
(defun Y-axis-column
(height width-of-label &optional vertical-step)
"Construct list of labels for Y axis.
HEIGHT is maximum height of graph.
WIDTH-OF-LABEL is maximum width of label.
VERTICAL-STEP, an option, is a positive integer
that specifies how much a Y axis label increments
for each line. For example, a step of 5 means
that each line is five units of the graph."
(let (Y-axis (number-per-line (or vertical-step 1))) (while (> height 1) (if (zerop (% height Y-axis-label-spacing))
;; Insert label.
(setq Y-axis
(cons
(Y-axis-element
(* height number-per-line)
width-of-label)
Y-axis))
;; Else, insert blanks.
(setq Y-axis
(cons
(make-string width-of-label ? )
Y-axis)))
(setq height (1- height)))
;; Insert base line.
(setq Y-axis (cons (Y-axis-element
(or vertical-step 1)
width-of-label)
Y-axis))
(nreverse Y-axis)))
The values for the maximum height of graph and the width of a symbol
are computed by print-graph in its let expression; so
graph-body-print must be changed to accept them.
;;; Final version.
(defun graph-body-print (numbers-list height symbol-width)
"Print a bar graph of the NUMBERS-LIST.
The numbers-list consists of the Y-axis values.
HEIGHT is maximum height of graph.
SYMBOL-WIDTH is number of each column."
(let (from-position) (while numbers-list (setq from-position (point)) (insert-rectangle (column-of-graph height (car numbers-list))) (goto-char from-position) (forward-char symbol-width)
;; Draw graph column by column. (sit-for 0) (setq numbers-list (cdr numbers-list))) ;; Place point for X axis labels. (forward-line height) (insert "\n")))
Finally, the code for the print-graph function:
;;; Final version.
(defun print-graph
(numbers-list &optional vertical-step)
"Print labeled bar graph of the NUMBERS-LIST.
The numbers-list consists of the Y-axis values.
Optionally, VERTICAL-STEP, a positive integer, specifies how much a Y axis label increments for each line. For example, a step of 5 means that each row is five units."
(let* ((symbol-width (length graph-blank))
;; height is both the largest number
;; and the number with the most digits.
(height (apply 'max numbers-list))
(height-of-top-line
(if (zerop (% height Y-axis-label-spacing))
height
;; else
(* (1+ (/ height Y-axis-label-spacing))
Y-axis-label-spacing)))
(vertical-step (or vertical-step 1)) (full-Y-label-width (length
(concat (number-to-string (* height-of-top-line vertical-step)) Y-axis-tic))))
(print-Y-axis height-of-top-line full-Y-label-width vertical-step)
(graph-body-print numbers-list height-of-top-line symbol-width) (print-X-axis numbers-list)))
Next: Testing print-graph, Up: Printing the Whole Graph [Contents][Index]