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[求助] 在看例子时有几个问题看不懂

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发表于 2012-6-20 08:59:43 | 显示全部楼层 |阅读模式
新手,在看netlogo自带的例子时,有几行程序看不懂,希望高手能够指点。
* ^0 l9 |1 E/ Wnetlogo自带的social science--traffic grid这一例子当中,+ U( x4 }5 x- Y6 A0 o8 Z+ A
globals
  n# \: H! b! u: @, j, u[, F: r' X6 {& u; M3 U, N
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
7 k. m: p& i  Q& o: Z6 |  grid-y-inc               ;; the amount of patches in between two roads in the y direction
8 e& S6 C( C; m- n& c& ~  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
/ h* w2 Y5 D3 c6 n1 p; J                           ;; it is to accelerate or decelerate" _' i1 N/ x0 G2 D! E
  phase                    ;; keeps track of the phase
: b9 @. `8 F0 i- L) x. }, x  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
+ B" J2 k; F& p- j  current-light            ;; the currently selected light  |" R& K% `. x) x2 f" k5 R  K
. `% V/ h1 ]( H) f9 b' o3 i( ~
  ;; patch agentsets  V5 V1 q) _6 B% ?* N3 W) f
  intersections ;; agentset containing the patches that are intersections- f9 a; w# K/ M% [9 q
  roads         ;; agentset containing the patches that are roads6 f7 {% }3 G4 K3 g, Y
]! F; G& a2 K! M
, E; @% [% X  I$ S9 W% Z9 \
turtles-own5 q: |' v3 r$ p3 O& ~5 K3 C4 [) n
[0 h/ X& k4 d: X7 F0 P, t$ f
  speed     ;; the speed of the turtle' V" f% h. }2 J6 A) S
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
; U/ K' j$ @5 v+ t* r4 r- x  wait-time ;; the amount of time since the last time a turtle has moved. r, X6 P- U/ j& Y9 r
]
- _7 s( \! L' i- n( i$ ^+ n* i4 Q7 ^0 ^$ l9 m; ?8 F0 p
patches-own7 b$ t: _( H) w% c: L  n6 b; E
[) o5 g2 ^, k6 O) y/ K
  intersection?   ;; true if the patch is at the intersection of two roads3 a9 s2 `  t0 h& c( z
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.* q# }. Z0 A8 P) ^, p0 J0 l. H
                  ;; false for a non-intersection patches.
' q5 ]" q8 Q+ C! D3 H6 Z  my-row          ;; the row of the intersection counting from the upper left corner of the
: w) S. W9 h9 P2 M( D                  ;; world.  -1 for non-intersection patches." z7 q1 U* P5 D# M; i5 N9 |  n
  my-column       ;; the column of the intersection counting from the upper left corner of the
" ]% O- M- c4 B                  ;; world.  -1 for non-intersection patches.
0 ~% `5 Y! h1 s; `! C  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
0 T, o* z- F3 p. M  auto?           ;; whether or not this intersection will switch automatically.2 q( R% R- g# U: n' L
                  ;; false for non-intersection patches.. ]* g9 i- v+ \$ T% b& S3 X5 i3 V& \
]
2 q4 V" w8 e% J/ ?/ u/ t/ U: Z
6 p- t0 j- ^, f+ V! R
& \& G  ?! u& q8 G% P5 G1 A9 }3 [5 A. S;;;;;;;;;;;;;;;;;;;;;;
6 Q! q8 T; g2 \( a# l8 n  z;; Setup Procedures ;;
1 C  M+ a1 c  F4 N& Q8 P" \5 P;;;;;;;;;;;;;;;;;;;;;;
+ {3 ]# Q6 D. R
: ~7 J+ @' h4 T;; Initialize the display by giving the global and patch variables initial values.: _: f9 T0 l4 [5 D" f! w
;; Create num-cars of turtles if there are enough road patches for one turtle to0 D' y: L6 q2 q8 B1 c/ k
;; be created per road patch. Set up the plots.1 x2 N6 t- y. v8 g. M/ [
to setup
; I# `0 c) }3 L  ca
5 K' H& }% v& T4 x+ q2 m. B6 X. `9 y  setup-globals% `* v( l' R( K; t

7 }1 l2 l% M2 K; e  ;; First we ask the patches to draw themselves and set up a few variables( p1 f* ]" v+ H2 o4 ^
  setup-patches  {4 V7 o& P- `. n$ F+ {
  make-current one-of intersections
+ y  i+ K" h0 s3 P2 O" \3 S! N  label-current
" o0 O; T- @5 v' k2 N. G/ i$ q; ?( D. b9 u4 k
  set-default-shape turtles "car"9 b& L( l5 @  e- B
4 [6 S: _9 C$ M* |
  if (num-cars > count roads)" {4 ]( P- s" x) V* e
  [- W2 _6 f: N& l9 P5 V
    user-message (word "There are too many cars for the amount of "
  {, K% J- u2 q; L' F8 h7 o2 T* ~                       "road.  Either increase the amount of roads "2 K9 S) Y. }+ p, D/ O6 x8 r/ N
                       "by increasing the GRID-SIZE-X or "! [) y, F! k, e7 u5 z; _8 u
                       "GRID-SIZE-Y sliders, or decrease the "
2 G3 [) b& y- Q$ J                       "number of cars by lowering the NUMBER slider.\n"
; u( z( |2 ?2 h- @9 `/ E+ j                       "The setup has stopped.")6 D: [7 @/ F/ y% X
    stop; c0 W. e6 g* e. V  f" Y. a
  ]
& M8 X, o& M, ~: p0 a- j$ k8 {# G
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color" G- d/ V6 v7 f1 }
  crt num-cars
7 ?$ J9 {3 X- J+ O  [
" x2 s! j" O3 N) l- P    setup-cars# `8 n# z  M# _* @7 G$ u/ _
    set-car-color
  H7 \! x" ?: a5 I    record-data0 B- D, v2 B5 L$ z
  ], v, s- p0 y% B- P7 V3 }- }% q

, r7 n- B. z- U& V4 ~4 p  ;; give the turtles an initial speed# J' G- }/ Z7 k1 w! t8 c1 U
  ask turtles [ set-car-speed ]
# q/ j, x" o6 [. b0 O- E: D7 Z* b3 Y/ A6 j6 c, \# O& w
  reset-ticks7 A4 h; s7 E5 `: N
end' U% o7 T: m6 n! ~
0 w' Z" z3 d8 X6 K) z; k7 d
;; Initialize the global variables to appropriate values: ~( U5 E6 f* n$ U7 {
to setup-globals7 b# V* G  S3 \" X
  set current-light nobody ;; just for now, since there are no lights yet- b. L8 a7 l* s4 y
  set phase 0- l% G( f: _; u, G" A; V
  set num-cars-stopped 0
: H' V4 p! B1 N) v" O+ |  set grid-x-inc world-width / grid-size-x
: q) x- I- S" r* f  set grid-y-inc world-height / grid-size-y
$ Z- E. g3 ?* p4 a
3 X% p. q3 H3 a  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
$ C$ A- J5 V/ M  y1 N2 v; |  set acceleration 0.0992 @; W4 z4 k- f6 @' V! F
end
# {4 E3 ^" U8 I$ N. f7 b7 D2 H& j; _  z
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,' P/ ^0 U! i+ }/ T
;; and initialize the traffic lights to one setting$ T7 W  B5 u4 P8 U8 N4 D- q
to setup-patches
  [$ C/ f1 i2 K% u; S/ J8 C  ;; initialize the patch-owned variables and color the patches to a base-color
7 i9 ^1 K6 b2 f& Z1 \$ N2 A  ask patches; J$ Z* t. c0 x# s% J, }6 }
  [
. n; v1 g- D2 q( W! y    set intersection? false
+ ]: `( M4 T) \# Y. g    set auto? false
9 n+ L7 z4 ?. K8 c    set green-light-up? true
1 ~* o% d4 p. |6 C& Y* b! C    set my-row -1
# Z) L  e& q  P# U4 C    set my-column -1
) B+ J. x+ f! _" Q* G    set my-phase -1
8 |$ B  ^: y# J# U    set pcolor brown + 3
2 N5 P6 s& ^1 j$ `2 ]- x  ]
0 [3 \& J! [  ~' d; `# }5 T. C$ y7 q4 u9 D- ]
  ;; initialize the global variables that hold patch agentsets5 ]! r. K, N3 H% J
  set roads patches with" r7 ^5 G3 l, m3 r- A$ X0 R; n6 ^
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
7 v2 _: R3 J+ A" L( l9 b3 A    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
+ U$ a7 W& F0 v; j% b4 r  set intersections roads with0 ~6 L  i. y8 x, j1 B
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
) f" Z" p$ f& V2 ~) g& ]    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]8 n/ L. [0 C, y/ o

. B7 W6 V: n& t( o  ask roads [ set pcolor white ]
6 J* ~4 c2 h8 Q5 |0 ^2 R  Q    setup-intersections9 n# y2 n7 \% d% r6 b- `. x  E
end
8 d0 S6 s, s: R) b: }其中定义道路的句子,如下所示,是什么意思啊?
. f. v, X4 M; ^7 w- e2 g set roads patches with
- I5 y% M$ o. T* |" p4 O    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or' O0 h. O4 w3 X
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
- t! D. H) U) C/ D( z9 r. o谁能帮我解释一下[(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0)是什么意思吗?
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