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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。6 Y& I. |, V- K( y" ^
netlogo自带的social science--traffic grid这一例子当中,) z7 h; o1 E9 n' R
globals
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$ F0 u6 x3 [' ?5 L5 s  grid-x-inc               ;; the amount of patches in between two roads in the x direction
7 U( ]: N1 J0 K5 A# P6 e  grid-y-inc               ;; the amount of patches in between two roads in the y direction: |- m2 ?1 n8 }# [3 w' [7 R; H& C
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
% A* h! V5 i3 L, I/ u  L                           ;; it is to accelerate or decelerate9 ?4 j3 {# P/ J/ q2 x8 W
  phase                    ;; keeps track of the phase
8 S5 `/ ~: |2 ?1 B3 Z/ y  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
- S. D, S  K& O/ E* F1 E6 {6 G  current-light            ;; the currently selected light
. l$ M+ r( z/ S+ s" f" Q* v/ m
* P% |; ]' m; s: \  ;; patch agentsets
2 [+ x+ |( C+ i  intersections ;; agentset containing the patches that are intersections6 `6 L' F/ U0 q5 G/ U. c
  roads         ;; agentset containing the patches that are roads5 D& z. X6 G/ B+ f$ r5 ]3 l
]
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turtles-own
" B% t$ u. C% W, i6 \[
2 @: T+ k' S4 N4 r$ z1 n0 A2 Z  speed     ;; the speed of the turtle
% p" O, x, V) E/ m  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
/ I: J% n" E1 O7 b, C; H& X  wait-time ;; the amount of time since the last time a turtle has moved
1 x, m& C7 [) G]
+ n' E$ @9 ?2 x6 B& F8 V, W  i5 c1 x9 p1 q  ]; o4 h1 `; u: H4 j4 z
patches-own7 i. ]2 B% z6 R
[
* T4 q+ N& L1 i3 W0 A& Y! p' d- a: l  intersection?   ;; true if the patch is at the intersection of two roads
5 v6 {7 }$ W- b  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.8 h6 w; d! l) `2 Z5 C# o
                  ;; false for a non-intersection patches.
' l. d6 z1 X1 c5 b  my-row          ;; the row of the intersection counting from the upper left corner of the
. e4 ~! y! _9 J' y                  ;; world.  -1 for non-intersection patches.* g1 x! g$ j& P  x; `% K8 O" o
  my-column       ;; the column of the intersection counting from the upper left corner of the
' v' e6 @- U9 X/ g3 T" p                  ;; world.  -1 for non-intersection patches.
# O3 o; N4 Y0 o. T6 e- P  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.7 i$ w. @1 o7 I! E
  auto?           ;; whether or not this intersection will switch automatically.2 U! M: L7 D5 d. _' G2 s
                  ;; false for non-intersection patches.
) O  ]* j( O. }  j. U5 ]2 M  C]
' F& y2 z5 F8 w8 O7 n* B; g  d
. g: h+ ]1 y# M. L, ]7 L" o) O3 F5 L4 T4 h/ f, V3 K: e5 j
;;;;;;;;;;;;;;;;;;;;;;
+ l1 ~/ M3 f6 _& a/ C3 ~;; Setup Procedures ;;' I' k  a. C7 r3 p5 W! x! j0 C, e5 q
;;;;;;;;;;;;;;;;;;;;;;
+ c3 Q. u- t1 b+ ?+ W  h  A9 h& U5 M8 d
;; Initialize the display by giving the global and patch variables initial values.  c0 `" A# V( i& G
;; Create num-cars of turtles if there are enough road patches for one turtle to1 b+ C, p1 T7 B6 q/ \
;; be created per road patch. Set up the plots.% ]0 L8 j) A: ^: m& h3 h! \8 O' t
to setup
& ?) W& ^9 g/ U% }" e; Q3 @$ {  ca6 ^4 t/ y: E! U. |8 m% u6 y
  setup-globals
9 N4 c# W5 B5 p
/ s! M# t0 \  ^$ C3 u* j  ;; First we ask the patches to draw themselves and set up a few variables$ M, ^" h6 Y  ?# a$ [, E- \9 f& L2 [
  setup-patches
% }$ W5 J7 `' e* I; q/ f  make-current one-of intersections
+ K' a! h7 A0 S7 {1 b# M, {0 Q+ @  label-current
$ K) U. i4 X8 D8 }  O& X& O  P5 z; O. O3 c. ~- U
  set-default-shape turtles "car"
# y2 l& e/ L6 y# {5 y! n2 [/ \2 h1 K. m. e; ~: B' f; Q* A4 x
  if (num-cars > count roads)
$ [/ n* O" h) `! Z9 D  [
7 a3 a/ v" L) Y) j    user-message (word "There are too many cars for the amount of "# X% |& O) y% F) J) P( ^
                       "road.  Either increase the amount of roads "
+ g4 u8 v2 R# D* _7 f                       "by increasing the GRID-SIZE-X or ", B! F, s( Q# D, I% K* \5 y
                       "GRID-SIZE-Y sliders, or decrease the "
! ~* i' S# y# H                       "number of cars by lowering the NUMBER slider.\n"$ B3 g5 ]/ S: Q6 M0 R2 d
                       "The setup has stopped.")2 U& u$ ]5 P$ z
    stop
# e: Z# m1 h0 P; c' r( T% W  c- c  ]7 k' ^0 G  P1 Q% N# J
2 Y3 d3 S  r2 U7 T# l1 D6 D  Q
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
' X6 G$ }! z3 _2 e  crt num-cars
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% o0 Z+ f" m- r2 ?+ V    setup-cars1 W' E& C: Q$ A2 t2 Y
    set-car-color
  `) C* d' e& S( u    record-data/ ^8 v; H. I2 X% d8 L
  ]# B% ]6 i, J; \8 K
! I  I8 I& O! R$ g( s" j' c
  ;; give the turtles an initial speed
5 }3 e0 O( R/ \5 s% J. p  ask turtles [ set-car-speed ]
3 u- R& S! h7 D* m: D. N7 u' ]9 f  r/ h/ N
  reset-ticks* z4 y' h+ c! |/ G; |4 n" o( l* P
end* n" u" E1 ]/ \* S

3 J, r9 D$ w# G5 A;; Initialize the global variables to appropriate values
7 `1 }$ d' C1 N+ p; V( O$ O5 Nto setup-globals
3 W9 l3 C, N( u# v8 k2 O% J1 P  set current-light nobody ;; just for now, since there are no lights yet
9 I& b/ z: U, g+ n  set phase 0
1 L) t, ^" _' f. f: I8 ?7 o  set num-cars-stopped 0
4 L0 ?5 e: ]8 h5 a1 v; ~; l2 A  set grid-x-inc world-width / grid-size-x: i. _: r, u6 @& W! v* }
  set grid-y-inc world-height / grid-size-y7 z" y* n8 ~' p0 ]
1 c/ ~' l* s4 o3 D5 ]
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary5 b3 M- O/ c. {( ?
  set acceleration 0.099
2 [! U! u1 E* A7 g# yend8 g+ C1 e. O% ^5 R; v# W
7 {1 S0 a- e6 ]" ?
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
1 n+ q) C9 `4 W  r1 V. \+ n& s! P;; and initialize the traffic lights to one setting( z* J, `  X6 u2 r% y( w! H
to setup-patches+ _- c$ t& |, s: r  A- M( q
  ;; initialize the patch-owned variables and color the patches to a base-color; H4 Z6 b+ N% u3 x& _
  ask patches
* I8 W1 V" i* ^  e, G! g  [1 s2 T5 @4 ?/ _! V3 D  c2 y4 _4 g0 X
    set intersection? false) w6 ?9 w1 N0 U# R) d1 n
    set auto? false
) g: u% h" s5 B  L: C    set green-light-up? true' l) X/ g: m, Q& v4 W4 E
    set my-row -1. f& J2 n7 b7 _- ?" o' E
    set my-column -1" X9 s2 d+ d) r+ g
    set my-phase -1
( X- u; `6 \% B% i( q    set pcolor brown + 3' A; q  |: R) [' V/ |3 O7 _
  ]
# _* D  U$ o+ `4 g  R, j7 E) }8 c/ i( b6 U4 S& R- S) a
  ;; initialize the global variables that hold patch agentsets, A1 j# F, w' v5 t: C1 @' m
  set roads patches with9 D" I# V3 j! _! G, K2 N) M
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or/ i1 a5 @% i( T4 |
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]6 K% t( ~  j, ]
  set intersections roads with: l, |0 k) G( s& f' U/ X7 j1 X
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
& m& }7 u9 D0 T    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]. g1 F3 R+ K' |, W
( D1 X8 |) Y- g  E
  ask roads [ set pcolor white ]
0 l2 @6 Q) }4 H, `' A    setup-intersections$ Y* f7 w) b  [/ Y) K
end  W' k* b) @7 w7 L# d6 d
其中定义道路的句子,如下所示,是什么意思啊?; P6 {$ ?# a: x1 f3 \8 m
set roads patches with
6 `1 X7 G1 o" E# U2 k    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
# i" W( l" P1 Y% X; K8 l( J    (floor((pycor + max-pycor) mod grid-y-inc) = 0)], r  v" V0 Y6 l& @- }3 a/ `& U
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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