racket/collects/plot/common/ticks.rkt
2011-11-11 18:12:40 -07:00

668 lines
28 KiB
Racket
Raw Blame History

This file contains ambiguous Unicode characters

This file contains Unicode characters that might be confused with other characters. If you think that this is intentional, you can safely ignore this warning. Use the Escape button to reveal them.

#lang racket/base
;; Data structure that represents a tick, and functions that produce ticks.
(require racket/string racket/list racket/contract racket/pretty racket/match racket/sequence
"math.rkt"
"contract.rkt"
"contract-doc.rkt"
"format.rkt"
"utils.rkt"
"axis-transform.rkt"
"sample.rkt"
"date-time.rkt"
"currency.rkt")
(provide (all-defined-out))
(struct pre-tick (value major?) #:transparent)
(struct tick pre-tick (label) #:transparent)
(struct ticks (layout format) #:transparent
#:property prop:procedure
(λ (t x-min x-max)
(match-define (ticks layout format) t)
(define ts (layout x-min x-max))
(match-define (list (pre-tick xs majors) ...) ts)
(map tick xs majors (format x-min x-max ts))))
(defcontract ticks-layout/c (real? real? . -> . (listof pre-tick?)))
(defcontract ticks-format/c (real? real? (listof pre-tick?) . -> . (listof string?)))
(defparam ticks-default-number exact-positive-integer? 5)
;; ===================================================================================================
;; Helpers
(define-syntax-rule (with-exact-bounds x-min x-max body ...)
(cond [(x-min . >= . x-max)
(error 'bounds-check "expected min < max; given min = ~e and max = ~e" x-min x-max)]
[else (let ([x-min (inexact->exact x-min)]
[x-max (inexact->exact x-max)])
body ...)]))
(define (linear-seq-args x-min x-max step)
(define start (* (ceiling (/ x-min step)) step))
(define end (* (floor (/ x-max step)) step))
(define num (+ 1 (inexact->exact (round (/ (- end start) step)))))
(values start end num))
(define (linear-major-values/step x-min x-max step)
(define-values (start end num) (linear-seq-args x-min x-max step))
(linear-seq start end num))
(defproc (linear-minor-values/step [major-xs (listof real?)] [major-step real?]
[minor-ticks exact-nonnegative-integer?]) (listof real?)
(cond [(or (zero? minor-ticks) (empty? major-xs)) empty]
[else
(define major-start (first major-xs))
(define minor-step (/ major-step (+ minor-ticks 1)))
(for*/list ([x (in-list (cons (- major-start major-step) major-xs))]
[i (in-range 1 (+ minor-ticks 1))])
(+ x (* i minor-step)))]))
(defproc (tick-values->pre-ticks [major-xs (listof real?)] [minor-xs (listof real?)]
) (listof pre-tick?)
(define major-ts (map (λ (x) (pre-tick x #t)) major-xs))
(define minor-ts (map (λ (x) (pre-tick x #f)) minor-xs))
(sort (append major-ts minor-ts) < #:key pre-tick-value))
;; ===================================================================================================
;; Linear ticks (default tick function, evenly spaced)
(defproc (linear-tick-step+divisor [x-min real?] [x-max real?]
[max-ticks exact-positive-integer?]
[base (and/c exact-integer? (>=/c 2))]
[divisors (listof exact-positive-integer?)]
) (values real? exact-positive-integer?)
(define range (- x-max x-min))
(define mag (expt base (floor-log/base base range)))
(define ds (sort divisors >))
(let/ec break
(for* ([e (in-range (floor-log/base base max-ticks) -2 -1)]
[d (in-list ds)])
;(printf "new-d = ~v~n" (* d (expt base e)))
(define step (/ mag d (expt base e)))
(define-values (_start _end num) (linear-seq-args x-min x-max step))
(when (num . <= . max-ticks)
(break step d)))
;(printf "default!~n")
(values (/ range max-ticks) max-ticks)))
(defproc (linear-tick-values [x-min real?] [x-max real?]
[max-ticks exact-positive-integer?]
[base (and/c exact-integer? (>=/c 2))]
[divisors (listof exact-positive-integer?)]
) (values (listof real?) (listof real?))
(with-exact-bounds
x-min x-max
(define-values (step d) (linear-tick-step+divisor x-min x-max max-ticks base divisors))
(define major-xs (linear-major-values/step x-min x-max step))
(define major-ticks (length major-xs))
(define ns (filter (λ (n) (zero? (remainder (* n d) base))) divisors))
(define n
(cond [(empty? ns) 1]
[else (argmin (λ (n) (abs (- (* n major-ticks) max-ticks))) (sort ns <))]))
(define minor-xs (linear-minor-values/step major-xs step (- n 1)))
(values major-xs (filter (λ (x) (<= x-min x x-max)) minor-xs))))
(defproc (linear-ticks-layout [#:number number exact-positive-integer? (ticks-default-number)]
[#:base base (and/c exact-integer? (>=/c 2)) 10]
[#:divisors divisors (listof exact-positive-integer?) '(1 2 5)]
) ticks-layout/c
(λ (x-min x-max)
(define-values (major-xs minor-xs) (linear-tick-values x-min x-max number base divisors))
(tick-values->pre-ticks major-xs minor-xs)))
(defproc (linear-ticks-format) ticks-format/c
(λ (x-min x-max ts)
(with-exact-bounds
x-min x-max
(define digits (digits-for-range x-min x-max))
(for/list ([t (in-list ts)])
(real->plot-label (pre-tick-value t) digits)))))
(defproc (linear-ticks [#:number number exact-positive-integer? (ticks-default-number)]
[#:base base (and/c exact-integer? (>=/c 2)) 10]
[#:divisors divisors (listof exact-positive-integer?) '(1 2 5)]
) ticks? #:document-body
(ticks (linear-ticks-layout #:number number #:base base
#:divisors divisors)
(linear-ticks-format)))
;; ===================================================================================================
;; No ticks
(defthing no-ticks-layout ticks-layout/c #:document-value
(λ (x-min x-max) empty))
(defthing no-ticks-format ticks-format/c #:document-value
(λ (x-min x-max pre-ticks)
(map (λ (_) "") pre-ticks)))
(defthing no-ticks ticks? #:document-value
(ticks no-ticks-layout no-ticks-format))
;; ===================================================================================================
;; Exponential ticks (for log scale)
(defproc (log-ticks-layout [#:number number exact-positive-integer? (ticks-default-number)]
[#:base base (and/c exact-integer? (>=/c 2)) 10]
) ticks-layout/c
(λ (x-min x-max)
(with-exact-bounds
x-min x-max
(when ((exact->inexact x-min) . <= . 0)
(raise-type-error 'log-ticks-layout "positive real" 0 x-min x-max))
(define log-start (ceiling-log/base base x-min))
(define log-end (floor-log/base base x-max))
(define skip (max 1 (ceiling (/ (+ 1 (- log-end log-start)) number))))
(filter (λ (t) (<= x-min (pre-tick-value t) x-max))
(append*
(for/list ([log-x (in-range (- log-start 1) (+ log-end 2))]
[m (in-cycle (in-range skip))])
(define x (expt base log-x))
(cond [(= skip 1) (for/list ([i (in-range 0 (sub1 base))])
(pre-tick (+ x (* i x))
(and (zero? i) (zero? m))))]
[else (list (pre-tick x (zero? m)))])))))))
(defproc (log-ticks-format [#:base base (and/c exact-integer? (>=/c 2)) 10]) ticks-format/c
(define base-str (number->string base))
(λ (x-min x-max ts)
(with-exact-bounds
x-min x-max
(define epsilon (expt 10 (- (digits-for-range x-min x-max))))
(define base-digits (digits-for-range 0 base))
(for/list ([t (in-list ts)])
(define x (pre-tick-value t))
(define log-x (floor-log/base base x))
(define (major-str)
(if (zero? log-x) "1" (format "~a~a" base-str (integer->superscript log-x))))
(cond [((abs (- x (expt base log-x))) . < . epsilon) (major-str)]
[(zero? log-x) (real->plot-label x base-digits)]
[else (format "~a×~a"
(real->plot-label (/ x (expt base log-x)) base-digits)
(major-str))])))))
(defproc (log-ticks [#:number number exact-positive-integer? (ticks-default-number)]
[#:base base (and/c exact-integer? (>=/c 2)) 10]
) ticks? #:document-body
(ticks (log-ticks-layout #:number number #:base base)
(log-ticks-format #:base base)))
;; ===================================================================================================
;; Date/time helpers
(defproc (find-linear-tick-step [x-min real?] [x-max real?] [max-ticks exact-positive-integer?]
[steps (listof real?)]) real?
(with-exact-bounds
x-min x-max
(let/ec break
(for ([step (in-list (sort steps <))])
(define-values (_start _end num) (linear-seq-args x-min x-max step))
(when (num . <= . max-ticks)
(break step)))
#f)))
(define (count-changing-fields formatter fmt-list xs)
(let ([fmt-list (filter symbol? fmt-list)])
(define formatted-dates (for/list ([x (in-list xs)])
(apply-formatter formatter fmt-list x)))
(count (λ (fields) (not (apply equal?* fields)))
(transpose formatted-dates))))
;; Find the shortest format string that has the maximum number of changing fields
(define (choose-format-list formatter fmt-lists xs)
(let ([fmt-lists (sort fmt-lists <
#:key (λ (fmt-list) (count symbol? fmt-list))
#:cache-keys? #t)])
(argmax (λ (fmt-list) (count-changing-fields formatter fmt-list xs))
fmt-lists)))
;; ===================================================================================================
;; Date ticks
(defthing 24h-descending-date-ticks-formats (listof string?) #:document-value
'("~Y-~m-~d ~H:~M:~f"
"~Y-~m-~d ~H:~M"
"~Y-~m-~d ~Hh"
"~Y-~m-~d"
"~Y-~m"
"~Y"
"~m-~d ~H:~M:~f"
"~m-~d ~H:~M"
"~m-~d ~Hh"
"~m-~d"
"~H:~M:~f"
"~H:~M"
"~Hh"
"~M:~fs"
"~Mm"
"~fs"))
(defthing 12h-descending-date-ticks-formats (listof string?) #:document-value
'("~Y-~m-~d ~I:~M:~f ~p"
"~Y-~m-~d ~I:~M ~p"
"~Y-~m-~d ~I ~p"
"~Y-~m-~d"
"~Y-~m"
"~Y"
"~m-~d ~I:~M:~f ~p"
"~m-~d ~I:~M ~p"
"~m-~d ~I ~p"
"~m-~d"
"~I:~M:~f ~p"
"~I:~M ~p"
"~I ~p"
"~M:~fs"
"~Mm"
"~fs"))
(defparam date-ticks-formats (listof string?) 24h-descending-date-ticks-formats)
;; Tick steps to try, in seconds
(define date-steps
(list 1 2 5 10 15 20 30 40 45
seconds-per-minute
(* 2 seconds-per-minute)
(* 5 seconds-per-minute)
(* 10 seconds-per-minute)
(* 15 seconds-per-minute)
(* 20 seconds-per-minute)
(* 30 seconds-per-minute)
seconds-per-hour
(* 2 seconds-per-hour)
(* 3 seconds-per-hour)
(* 4 seconds-per-hour)
(* 6 seconds-per-hour)
(* 8 seconds-per-hour)
(* 12 seconds-per-hour)
seconds-per-day
(* 2 seconds-per-day)
(* 5 seconds-per-day)
(* 10 seconds-per-day)
seconds-per-week
(* 2 seconds-per-week)
avg-seconds-per-month
(* 2 avg-seconds-per-month)
(* 3 avg-seconds-per-month)
(* 4 avg-seconds-per-month)
(* 6 avg-seconds-per-month)
(* 8 avg-seconds-per-month)
(* 9 avg-seconds-per-month)
avg-seconds-per-year
(* 2 avg-seconds-per-year)
(* 5 avg-seconds-per-year)))
(define (date-tick-values x-min x-max max-ticks)
(with-exact-bounds
x-min x-max
(define range (- x-max x-min))
(define step
(cond [(range . < . (* max-ticks (first date-steps)))
(define-values (step _)
(linear-tick-step+divisor x-min x-max max-ticks 10 '(1 2 5)))
step]
[(range . > . (* max-ticks (last date-steps)))
(define-values (step _)
(linear-tick-step+divisor (/ x-min avg-seconds-per-year)
(/ x-max avg-seconds-per-year)
max-ticks 10 '(1 2 5)))
(* step avg-seconds-per-year)]
[else (find-linear-tick-step x-min x-max max-ticks date-steps)]))
(define date-round
(cond [(step . >= . avg-seconds-per-year) utc-seconds-round-year]
[(step . >= . avg-seconds-per-month) utc-seconds-round-month]
[else (λ (d) d)]))
(define major-xs (linear-major-values/step x-min x-max step))
(values (map date-round major-xs) empty)))
(defproc (date-ticks-layout [#:number number exact-positive-integer? (ticks-default-number)]
) ticks-layout/c
(λ (x-min x-max)
(define-values (major-xs minor-xs) (date-tick-values x-min x-max number))
(tick-values->pre-ticks major-xs minor-xs)))
(defproc (date-ticks-format [#:formats formats (listof string?) (date-ticks-formats)]) ticks-format/c
(define fmt-lists (map parse-format-string formats))
(λ (x-min x-max ts)
(with-exact-bounds
x-min x-max
(define formatter (plot-date-formatter x-min x-max))
(define xs (map pre-tick-value ts))
(cond [(empty? xs) empty]
[else
(define fmt-list (choose-format-list formatter fmt-lists xs))
(cons (string-append* (apply-formatter formatter fmt-list (first xs)))
(for/list ([last-x (in-list xs)] [x (in-list (rest xs))])
(define fmt-list (choose-format-list formatter fmt-lists (list last-x x)))
(string-append* (apply-formatter formatter fmt-list x))))]))))
(defproc (date-ticks [#:number number exact-positive-integer? (ticks-default-number)]
[#:formats formats (listof string?) (date-ticks-formats)]
) ticks? #:document-body
(ticks (date-ticks-layout #:number number)
(date-ticks-format #:formats formats)))
;; ===================================================================================================
;; Time ticks
(defthing 24h-descending-time-ticks-formats (listof string?) #:document-value
'("~dd ~H:~M:~f"
"~dd ~H:~M"
"~dd ~Hh"
"~dd"
"~H:~M:~f"
"~H:~M"
"~Hh"
"~M:~fs"
"~Mm"
"~fs"))
(defthing 12h-descending-time-ticks-formats (listof string?) #:document-value
'("~dd ~I:~M:~f ~p"
"~dd ~I:~M ~p"
"~dd ~I ~p"
"~dd"
"~I:~M:~f ~p"
"~I:~M ~p"
"~I ~p"
"~M:~fs"
"~Mm"
"~fs"))
(defparam time-ticks-formats (listof string?) 24h-descending-time-ticks-formats)
;; Tick steps to try, in seconds
(define time-steps
(list 1 2 5 10 15 20 30 40 45
seconds-per-minute
(* 2 seconds-per-minute)
(* 5 seconds-per-minute)
(* 10 seconds-per-minute)
(* 15 seconds-per-minute)
(* 20 seconds-per-minute)
(* 30 seconds-per-minute)
(* 45 seconds-per-minute)
seconds-per-hour
(* 2 seconds-per-hour)
(* 3 seconds-per-hour)
(* 4 seconds-per-hour)
(* 6 seconds-per-hour)
(* 8 seconds-per-hour)
(* 12 seconds-per-hour)
(* 18 seconds-per-hour)
seconds-per-day
(* 2 seconds-per-day)
(* 5 seconds-per-day)
(* 10 seconds-per-day)
(* 15 seconds-per-day)
(* 30 seconds-per-day)
(* 60 seconds-per-day)
(* 90 seconds-per-day)))
(define (time-tick-values x-min x-max max-ticks)
(with-exact-bounds
x-min x-max
(define range (- x-max x-min))
(define step
(cond [(range . < . (* max-ticks (first time-steps)))
(define-values (step _)
(linear-tick-step+divisor x-min x-max max-ticks 10 '(1 2 5)))
step]
[(range . > . (* max-ticks (last time-steps)))
(define-values (step _)
(linear-tick-step+divisor (/ x-min seconds-per-day)
(/ x-max seconds-per-day)
max-ticks 10 '(1 2 5)))
(* step seconds-per-day)]
[else
(find-linear-tick-step x-min x-max max-ticks time-steps)]))
(define major-xs (linear-major-values/step x-min x-max step))
(values major-xs empty)))
(defproc (time-ticks-layout [#:number number exact-positive-integer? (ticks-default-number)]
) ticks-layout/c
(λ (x-min x-max)
(define-values (major-xs minor-xs) (time-tick-values x-min x-max number))
(tick-values->pre-ticks major-xs minor-xs)))
(defproc (time-ticks-format [#:formats formats (listof string?) (time-ticks-formats)]) ticks-format/c
(define fmt-lists (map parse-format-string formats))
(λ (x-min x-max ts)
(with-exact-bounds
x-min x-max
(define formatter (plot-time-formatter x-min x-max))
(define xs (map pre-tick-value ts))
(cond [(empty? xs) empty]
[else
(define fmt-list (choose-format-list formatter fmt-lists xs))
(cons (string-append* (apply-formatter formatter fmt-list (first xs)))
(for/list ([last-x (in-list xs)] [x (in-list (rest xs))])
(define fmt-list (choose-format-list formatter fmt-lists (list last-x x)))
(string-append* (apply-formatter formatter fmt-list x))))]))))
(defproc (time-ticks [#:number number exact-positive-integer? (ticks-default-number)]
[#:formats formats (listof string?) (time-ticks-formats)]
) ticks? #:document-body
(ticks (time-ticks-layout #:number number)
(time-ticks-format #:formats formats)))
;; ===================================================================================================
;; Byte and bit ticks
;; "", Kilo, Mega, Giga, Tera, Peta, Exa, Zeta, Yotta
(define byte-suffixes #("B" "KB" "MB" "GB" "TB" "PB" "EB" "ZB" "YB"))
(define bit-suffixes #("b" "Kb" "Mb" "Gb" "Tb" "Pb" "Eb" "Zb" "Yb"))
(defproc (bit/byte-ticks-format [#:size size (or/c 'byte 'bit) 'byte]
[#:kind kind (or/c 'CS 'SI) 'CS]) ticks-format/c
(λ (x-min x-max ts)
(with-exact-bounds
x-min x-max
(define suffixes (if (eq? size 'bit) bit-suffixes byte-suffixes))
(define-values (base pow) (case kind
[(SI) (values 10 3)]
[else (values 2 10)]))
(define x-largest (max* (abs x-min) (abs x-max)))
(define b (floor-log/base (expt base pow) x-largest))
(define format-str
(cond [(and (b . >= . 0) (b . < . (vector-length suffixes)))
(format "~a ~a" "~a" (vector-ref suffixes b))]
[else
(format "~a×~a~a ~a" "~a"
base (integer->superscript (* b pow)) (vector-ref suffixes 0))]))
(define unit (expt base (* b pow)))
(define digits (digits-for-range (/ x-min unit) (/ x-max unit)))
(for/list ([t (in-list ts)])
(define unit-x (/ (pre-tick-value t) unit))
(format format-str (real->plot-label unit-x digits #f))))))
(defproc (bit/byte-ticks [#:number number exact-positive-integer? (ticks-default-number)]
[#:size size (or/c 'byte 'bit) 'byte]
[#:kind kind (or/c 'CS 'SI) 'CS]
) ticks? #:document-body
(define si? (eq? kind 'SI))
(ticks (linear-ticks-layout #:number number #:base (if si? 10 2)
#:divisors (if si? '(1 2 5) '(1 2)))
(bit/byte-ticks-format #:size size #:kind kind)))
;; ===================================================================================================
;; Currency
;; US "short scale" suffixes
(defthing us-currency-scales (listof string?) #:document-value '("" "K" "M" "B" "T"))
;; The UK officially uses the short scale since 1974
;; Million is abbreviated "m" instead of "mn" because "mn" stands for minutes
(defthing uk-currency-scales (listof string?) #:document-value '("" "k" "m" "bn" "tr"))
;; European countries use the long scale: million, milliard, billion
(defthing eu-currency-scales (listof string?) #:document-value '("" "K" "M" "Md" "B"))
;; The larger the scale suffixes get, the less standardized they are; so we stop at billion (long)
;; US negative amounts are in parenthesis:
(defthing us-currency-formats (list/c string? string? string?) #:document-value
'("~$~w.~f~s" "(~$~w.~f~s)" "~$0"))
;; The UK is more reasonable, using a negative sign for negative amounts:
(defthing uk-currency-formats (list/c string? string? string?) #:document-value
'("~$~w.~f~s" "-~$~w.~f~s" "~$0"))
;; The more common EU format (e.g. France, Germany, Italy, Spain):
(defthing eu-currency-formats (list/c string? string? string?) #:document-value
'("~w,~f ~s~$" "-~w,~f ~s~$" "0 ~$"))
(defparam currency-ticks-scales (listof string?) us-currency-scales)
(defparam currency-ticks-formats (list/c string? string? string?) us-currency-formats)
(struct amount-data (sign whole fractional unit suffix) #:transparent)
(define (currency-formatter x-min x-max)
(λ (fmt data)
(case fmt
[(~$) (amount-data-sign data)]
[(~w) (number->string (amount-data-whole data))]
[(~f) (match-define (amount-data _sign _whole f unit _suffix) data)
(define digits (digits-for-range (/ x-min unit) (/ x-max unit)))
(cond [(= 1 unit) (substring (real->decimal-string* f 2 (max 2 digits)) 2)]
[(zero? f) "0"]
[else (substring (real->decimal-string* f 1 (max 1 digits)) 2)])]
[(~s) (amount-data-suffix data)]
[else #f])))
(defproc (currency-ticks-format [#:kind kind (or/c string? symbol?) 'USD]
[#:scales scales (listof string?) (currency-ticks-scales)]
[#:formats formats (list/c string? string? string?)
(currency-ticks-formats)]
) ticks-format/c
(match-define (list positive-format-string negative-format-string zero-format-string) formats)
(define positive-format-list (parse-format-string positive-format-string))
(define negative-format-list (parse-format-string negative-format-string))
(define zero-format-list (parse-format-string zero-format-string))
(define suffixes (list->vector scales))
(define n (vector-length suffixes))
(λ (x-min x-max ts)
(with-exact-bounds
x-min x-max
(define formatter (currency-formatter x-min x-max))
(define sign (cond [(string? kind) kind]
[else (hash-ref currency-code->sign kind (λ () (symbol->string kind)))]))
(define x-largest (max* (abs x-min) (abs x-max)))
(define b (let ([b (floor-log/base 1000 x-largest)])
(if (b . < . 0) (+ b 1) b)))
(define suffix
(cond [(and (b . >= . 0) (b . < . n)) (vector-ref suffixes b)]
[else (format "×10~a" (integer->superscript (* b 3)))]))
(define unit
(cond [(= 0 (string-length suffix)) 1]
[else (expt 1000 b)]))
(for/list ([t (in-list ts)])
(define x (pre-tick-value t))
(define format-list (cond [(positive? x) positive-format-list]
[(negative? x) negative-format-list]
[else zero-format-list]))
(define unit-x (/ (abs x) unit))
(define whole (inexact->exact (floor unit-x)))
(define frac (- unit-x whole))
(string-append*
(apply-formatter formatter format-list
(amount-data sign whole frac unit suffix)))))))
(defproc (currency-ticks [#:number number exact-positive-integer? (ticks-default-number)]
[#:kind kind (or/c string? symbol?) 'USD]
[#:scales scales (listof string?) (currency-ticks-scales)]
[#:formats formats (list/c string? string? string?) (currency-ticks-formats)]
) ticks? #:document-body
(ticks (linear-ticks-layout #:number number #:base 10
#:divisors '(1 2 4 5))
(currency-ticks-format #:kind kind #:scales scales
#:formats formats)))
;; ===================================================================================================
;; Fractions
(define (format-fraction x)
(cond [(inexact? x) (format-fraction (inexact->exact x))]
[(x . < . 0) (format "-~a" (format-fraction (- x)))]
[(x . = . 0) "0"]
[(x . < . 1) (format "~a/~a" (numerator x) (denominator x))]
[else
(define d (denominator x))
(cond [(d . = . 1) (format "~a" (numerator x))]
[else
(define w (floor x))
(let ([x (- x w)])
(format "~a ~a/~a" w (numerator x) (denominator x)))])]))
(defproc (fraction-ticks-format) ticks-format/c
(λ (x-min x-max ts)
(for/list ([t (in-list ts)])
(format-fraction (pre-tick-value t)))))
(defproc (fraction-ticks [#:base base (and/c exact-integer? (>=/c 2)) 10]
[#:divisors divisors (listof exact-positive-integer?) '(1 2 3 4 5)]
) ticks? #:document-body
(ticks (linear-ticks #:base base #:divisors divisors)
(fraction-ticks-format)))
;; ===================================================================================================
;; Tick combinators
(defproc (ticks-mimic [thunk (-> ticks?)]) ticks?
(ticks (λ (x-min x-max) ((ticks-layout (thunk)) x-min x-max))
(λ (x-min x-max ts) ((ticks-format (thunk)) x-min x-max ts))))
(defproc (ticks-scale [t ticks?] [fun invertible-function?]) ticks?
(match-define (invertible-function f g) fun)
(match-define (ticks layout format) t)
(ticks (λ (x-min x-max)
(define ts (layout (f x-min) (f x-max)))
(for/list ([t (in-list ts)])
(match-define (pre-tick x major?) t)
(pre-tick (g x) major?)))
(λ (x-min x-max ts)
(format (f x-min) (f x-max) (map (λ (t)
(match-define (pre-tick x major?) t)
(pre-tick (f x) major?))
ts)))))
(defproc (ticks-add [t ticks?] [xs (listof real?)] [major? boolean? #t]) ticks?
(match-define (ticks layout format) t)
(ticks (λ (x-min x-max)
(append (layout x-min x-max)
(for/list ([x (in-list xs)])
(pre-tick x major?))))
format))
(defproc (linear-scale [m real?] [b real? 0]) invertible-function? #:document-body
(invertible-function (λ (x) (+ (* m x) b))
(λ (y) (/ (- y b) m))))
;; ===================================================================================================
;; Tick utils
(define (same-label? t1 t2) (string=? (tick-label t1) (tick-label t2)))
(define (collapse-equiv-ticks ts near-format-string)
(match-define (list (tick xs majors labels) ...) ts)
(define x (/ (apply + xs) (length ts)))
(define major? (ormap values majors))
(define label1 (first labels))
(define label2 (last labels))
(define label
(cond [(string=? label1 label2) label1]
[else (format near-format-string label1 label2)]))
(tick x major? label))
(defproc (collapse-ticks [ts (listof tick?)] [near? (tick? tick? . -> . boolean?)]
[near-format-string string? "~a|~a"]) (listof tick?)
(let ([ts (sort ts < #:key pre-tick-value)])
(append*
(for/list ([ts (in-list (group-neighbors
ts (λ (t1 t2) (or (same-label? t1 t2) (near? t1 t2)))))])
(define n (length ts))
(define m (count pre-tick-major? ts))
(cond [(n . <= . 1) ts]
[(m . = . 0) (list (collapse-equiv-ticks ts near-format-string))]
[(m . = . 1) (filter pre-tick-major? ts)]
[else (list (collapse-equiv-ticks (filter pre-tick-major? ts) near-format-string))])))))