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The preceding functions provide all the tools needed to construct a function that generates a list of numbered and blank strings to insert as the label for the vertical axis:

(defun Y-axis-column (height width-of-label) "Construct list of Y axis labels and blank strings. For HEIGHT of line above base and WIDTH-OF-LABEL." (let (Y-axis)

```
(while (> height 1)
(if (zerop (% height Y-axis-label-spacing))
;; Insert label.
(setq Y-axis
(cons
(Y-axis-element height 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 1 width-of-label) Y-axis)) (nreverse Y-axis)))

In this function, we start with the value of `height`

and
repetitively subtract one from its value. After each subtraction, we
test to see whether the value is an integral multiple of the
`Y-axis-label-spacing`

. If it is, we construct a numbered label
using the `Y-axis-element`

function; if not, we construct a
blank label using the `make-string`

function. The base line
consists of the number one followed by a tic mark.