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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。1 ]6 C$ w! _6 ^6 x. z
netlogo自带的social science--traffic grid这一例子当中,
" C) T! c$ c/ W1 Gglobals# B  J) w! G, D
[; y: g: E, p+ v
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
: {5 l3 ?, }6 r2 e2 u5 i& j  grid-y-inc               ;; the amount of patches in between two roads in the y direction
5 [. B$ d+ P: h  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
/ R: q9 Q8 c  b: L                           ;; it is to accelerate or decelerate
( G$ R9 v: o7 E: ~) F$ U5 h; p+ @/ o8 t  phase                    ;; keeps track of the phase
2 k+ t8 [0 t* g8 H& e7 P  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
$ Q9 [4 \( M* O, x! S0 ^  current-light            ;; the currently selected light
" n% f5 K/ D6 e; ~) C5 b! }
) H4 M0 A' B' _  ;; patch agentsets
1 e2 e2 e. m1 F8 d8 Y  intersections ;; agentset containing the patches that are intersections* D5 E8 K8 V1 G7 a( `8 {
  roads         ;; agentset containing the patches that are roads1 e/ _) x% O# m
]
; n3 j' z6 d4 R. X! z7 X; ~7 y
( X4 |' \7 w1 b! Y) |turtles-own
3 q2 F9 _, i3 @5 p6 p% p2 S0 M4 j[! O* C, }) `- p3 ?
  speed     ;; the speed of the turtle
* H  y# ?2 N- E6 `7 }7 }  up-car?   ;; true if the turtle moves downwards and false if it moves to the right( P8 C( O( |' [& E* M
  wait-time ;; the amount of time since the last time a turtle has moved. Z/ ~9 z9 y# E
]
. C) u' N, |1 M# e! c/ A; u& Z( K0 A+ s
patches-own4 N0 [8 r3 {2 S* O6 t5 e, B4 p1 U
[
& _' ]1 y9 Y% c7 T" J  intersection?   ;; true if the patch is at the intersection of two roads- w2 K6 W+ _7 x" e
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
/ Y7 o7 u" l# H1 d. I- u, \8 t* J* T                  ;; false for a non-intersection patches.* d& g9 p0 i/ Y2 E  C( }  \, s
  my-row          ;; the row of the intersection counting from the upper left corner of the
8 S5 j# E% m7 y1 r. W8 B8 y                  ;; world.  -1 for non-intersection patches.0 U% m& C# `+ W. W0 B! f. f
  my-column       ;; the column of the intersection counting from the upper left corner of the1 K% n  ?" M3 y
                  ;; world.  -1 for non-intersection patches.
/ j# p6 \' s3 h. Y8 r0 C  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.. C! |8 b! @3 d2 ^" M7 o! G
  auto?           ;; whether or not this intersection will switch automatically.1 }1 K4 f6 g8 O: F' Y
                  ;; false for non-intersection patches.; T$ I. V* z; D: |" l
]
  n- ^8 U) T. G$ `
5 V; B; Q# J$ F: n. W- O
; |& _5 J' d% Q+ R;;;;;;;;;;;;;;;;;;;;;;
! u+ X  b/ m& G9 g- X/ c. X;; Setup Procedures ;;
- b# n9 _" d! |5 J! a0 W;;;;;;;;;;;;;;;;;;;;;;
( ~+ `1 n9 \+ G, r
# q! @) N! N8 d;; Initialize the display by giving the global and patch variables initial values.. I% `6 b0 D0 Z
;; Create num-cars of turtles if there are enough road patches for one turtle to
+ z& w4 D7 @! L# g) q;; be created per road patch. Set up the plots.
/ t: ]8 @0 b4 h% |) g( V0 E$ Rto setup
5 h( H& O; \" O8 k9 [: L, l6 [& i  ca; e2 _: o8 W& u! t2 @
  setup-globals9 `. P* k4 k9 ?/ N

6 ?# m# S4 f# g- F: I9 u/ ^) C  ;; First we ask the patches to draw themselves and set up a few variables
6 P1 O# e! q0 h" F. @  setup-patches
+ n5 U+ E2 c/ _& c' ]  make-current one-of intersections
- K& N& d: h4 X  label-current" C! j* V6 d5 a4 K' {2 b2 R+ Z% j( ^
7 O: n% W9 \. i' H  ?; L/ ~
  set-default-shape turtles "car"1 M: w2 x  y/ [4 ^$ V( y1 Y6 H( A% O9 H
" V/ L2 G$ E% K8 c, ?
  if (num-cars > count roads)1 z( J+ t2 N2 }' O
  [' m: u# {! K# v/ y; {4 }" _
    user-message (word "There are too many cars for the amount of "/ ^! _4 m$ x- e" N
                       "road.  Either increase the amount of roads "2 q& Y& w5 F$ U/ V" h, N
                       "by increasing the GRID-SIZE-X or "9 b# A$ ]* l1 y* u5 v: c% |
                       "GRID-SIZE-Y sliders, or decrease the "
9 r, g; x5 Z8 C' m3 c                       "number of cars by lowering the NUMBER slider.\n"
7 p: `# B3 k# {/ z6 l                       "The setup has stopped.")/ t6 b: }/ f  Q1 F
    stop6 Z6 R0 _* H8 R( ]! b1 E3 F1 \
  ]& b, l! }0 N: w' e' J: l5 `4 I

$ a9 _9 y* M; `- J  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color# `4 {5 C: S$ n+ ]5 m9 y1 c  l
  crt num-cars0 R7 {/ U; t; t, ]3 X$ f! F9 U
  [
$ ]1 c) S- s1 ~6 e: N7 M# C    setup-cars3 q% a. C* b  t
    set-car-color; C+ N& E/ K; v: x% z/ B1 {
    record-data$ q; n& B" X6 n# |2 \
  ]
" |7 O& x$ P6 a; D4 b9 H% C  |9 l( O  z; Q+ ?. e0 ^5 T
  ;; give the turtles an initial speed# T4 `( q, E' b5 N5 V; Y: e4 n
  ask turtles [ set-car-speed ]9 J5 l$ N6 @& [8 X: z
' r, x! X( n4 m0 u3 c3 v2 ?
  reset-ticks
# P+ _! x! H3 Yend1 G$ J# w1 k& @; z! S; K2 C& S* y

; v$ A  K" C) \, q;; Initialize the global variables to appropriate values
6 @2 r% M& j; `1 sto setup-globals: w1 ?; d$ F2 k5 f, _2 D
  set current-light nobody ;; just for now, since there are no lights yet2 D, t; ^3 m% g! B
  set phase 0; R# p4 w( G& }  a! _7 U) \( H
  set num-cars-stopped 0
4 I! ?* C* E7 [. {- H; r  set grid-x-inc world-width / grid-size-x( h/ t0 Z. E) H6 s4 l3 q: b3 k% \8 v7 p/ A
  set grid-y-inc world-height / grid-size-y; I2 L+ Y- ?6 |: i2 \' ~
4 |4 |3 Q9 p1 X7 {% p
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
0 L  k* [/ F% v1 Y. N( h* Z$ a. h2 x+ `  set acceleration 0.0999 U/ V2 d7 X% k" v
end$ t! u$ R4 ~- y! i; A" b+ X

$ b) [* T2 e7 p8 V/ L;; Make the patches have appropriate colors, set up the roads and intersections agentsets,7 [7 Q+ n9 W$ t# }
;; and initialize the traffic lights to one setting0 m; w, C6 m2 x+ W; u2 }
to setup-patches
" E$ D& P; V5 m. |  ;; initialize the patch-owned variables and color the patches to a base-color
2 `; v& K5 w9 j* ~9 W( D  ask patches0 |8 `$ z0 O4 W# R* ~- n
  [' t5 U) f% R  T
    set intersection? false
$ V! t8 f" n# b; P, Q7 S    set auto? false
6 I! u6 g1 u/ N0 c& W: O9 g1 K( R    set green-light-up? true
2 M2 v( A  \( Y! Y) Q$ m5 k    set my-row -1
, L1 A" ?2 C  w1 Y% ~    set my-column -1# C" X& C' H4 s8 v0 `; m: O
    set my-phase -1$ P9 y- C& k" o
    set pcolor brown + 3/ E: |' |# s, s% N  q1 P
  ]3 A& f" Y8 V# k5 @5 j- V; B5 i
$ Z4 F+ K) _# k0 I; @
  ;; initialize the global variables that hold patch agentsets
7 S; `% c/ d, @  set roads patches with; F: Y$ U) Q* q/ _3 q  D+ e0 Z
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
1 W  u2 Y; ]( j4 H  X    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
) r8 M3 x* }& {: s( K( g8 Z  set intersections roads with
9 A/ a0 B: _0 k: N    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
1 }2 u, e0 C: A5 D% S    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
$ V# {( {( A7 P' l6 q, M2 ~3 K* w8 {/ k6 v
  ask roads [ set pcolor white ]8 T, G+ ]1 f/ U$ y! Z0 L
    setup-intersections
6 i* j" q! a# c( D! rend
5 k7 c: _6 U* I+ D其中定义道路的句子,如下所示,是什么意思啊?
; Z! p% r% }" @5 P% p- @9 g0 U5 o' N set roads patches with$ o" U8 F% Y4 z4 s& H
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or# \( ]1 ?. m  j" u! E
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]5 x9 L4 |, q! F9 \" e
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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