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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 o: |$ p- N. h8 I( q- J- C# C  X
netlogo自带的social science--traffic grid这一例子当中,( H; l0 Z- Y( R% T6 T" h  N  e" T
globals
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  grid-x-inc               ;; the amount of patches in between two roads in the x direction
, H$ G2 R$ v; r" A  grid-y-inc               ;; the amount of patches in between two roads in the y direction
! s" F/ Z: S" e0 N9 T  acceleration             ;; the constant that controls how much a car speeds up or slows down by if* i: _3 X% o" z' Y6 o
                           ;; it is to accelerate or decelerate
6 j* h6 v- t7 _/ ~0 R# J" @% E1 Q" ~  phase                    ;; keeps track of the phase1 U! |$ c. U0 }  a$ q
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure9 F- f* H6 ]5 i+ u( S
  current-light            ;; the currently selected light
* U; ^6 G  L- ]  a5 x. K8 Y$ K. m- E$ y, Z0 |( q& l
  ;; patch agentsets
  Z6 \' M2 M3 T, U; o" o1 B  intersections ;; agentset containing the patches that are intersections- j1 t- I: K0 D# v. i' {
  roads         ;; agentset containing the patches that are roads
# `( w: M1 H+ U8 @" U]  K2 O$ C# G- T3 X
. d' ]5 _- N9 @/ `+ i
turtles-own
' W& k4 L7 K: }( ?) B4 g[
0 F. i4 C; c( n) D- I) t) |0 E  speed     ;; the speed of the turtle4 |( @& N1 c; g& u9 _$ h, [+ N$ u
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
6 W) ?# q: c% |4 R  wait-time ;; the amount of time since the last time a turtle has moved
  n  C- h+ v0 r& Q- R]
! w  _% l  X* L/ n0 J
) F# K1 X% W" ?7 n8 G' ppatches-own5 R1 Y  T% v& f0 k& S/ g
[; r) B1 n6 ]9 ?: K- f( H
  intersection?   ;; true if the patch is at the intersection of two roads
, P, b0 ]( _& o; C# t/ ~  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
- B* v  g! }0 m  l* X8 L                  ;; false for a non-intersection patches.
9 {/ `  o1 \6 s. c8 e+ M; D$ C3 ^  my-row          ;; the row of the intersection counting from the upper left corner of the5 `$ W2 q7 u  u9 N4 Z) B4 X
                  ;; world.  -1 for non-intersection patches.
/ _5 m9 |& @1 X! c  my-column       ;; the column of the intersection counting from the upper left corner of the& O4 \) `; P! S4 H5 G8 Q
                  ;; world.  -1 for non-intersection patches.
: O: H9 u; X- y" d4 g+ G  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
6 @+ ~( |1 I& M+ Y  auto?           ;; whether or not this intersection will switch automatically.
! y9 U9 B: l" e! i$ V9 C                  ;; false for non-intersection patches.
8 g+ p( ~3 e9 C: @4 E]; d1 D/ u- B2 G# t

7 e  o1 w' c* s9 k7 V, Y  V, s: d1 K! e) n
;;;;;;;;;;;;;;;;;;;;;;
- B" ]# U- I, O* j1 a/ t;; Setup Procedures ;;4 q5 ^* ~: f' j) X
;;;;;;;;;;;;;;;;;;;;;;
" L. q9 Z' ?, J6 l7 X, h" I  t0 `3 G  j! T& g
;; Initialize the display by giving the global and patch variables initial values.( S& {. d: S. Q
;; Create num-cars of turtles if there are enough road patches for one turtle to: E( ~  y" g+ |" [$ k% q3 g% A
;; be created per road patch. Set up the plots., Y4 U! T5 P- N0 [
to setup! V3 A; h* y9 \
  ca
- u* e& _% ^: g/ J7 W  setup-globals
* w! y% }* n) m5 T# B
* h/ }6 @' h; V9 L$ U3 L$ @  ;; First we ask the patches to draw themselves and set up a few variables
1 I# T' ^, z' }% P7 E) X; p( N  setup-patches
0 I2 C6 l* i. n8 P3 A9 d  make-current one-of intersections! Y' L1 ]" U. O% g! @
  label-current
* L, X9 J) f  [) G) D. |) v3 E* f: A/ ^8 d& a; n4 R1 W; G6 e
  set-default-shape turtles "car"
) A0 f5 Y4 n$ e% K
7 K/ F4 J+ E; u# ^3 Q7 l8 e  if (num-cars > count roads)
/ X. d% z8 v8 ]) q+ P3 h) A5 o- _  [
; ]4 X! ]3 z+ \- n+ H2 \    user-message (word "There are too many cars for the amount of "" j. @5 N& ^; [: p4 M  I
                       "road.  Either increase the amount of roads "
/ c$ ]+ Z) W( j) d% S                       "by increasing the GRID-SIZE-X or ": ]8 r! @8 I9 M3 I% U" L8 ^% ?
                       "GRID-SIZE-Y sliders, or decrease the "/ `6 y# j; K3 g" o/ R
                       "number of cars by lowering the NUMBER slider.\n"
& D0 T$ D& g& j                       "The setup has stopped.")
3 \0 _7 A, v# t+ y& d; A, I& T  A    stop/ e* g: g1 B  J/ h
  ]
3 `0 L( ?; \9 ^
4 E; t$ B* j$ O  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color8 x% ?* ~: }' X9 Q# A& Y
  crt num-cars9 r. V  j+ c# H* A1 W* c8 G
  [
/ {2 |0 H3 p% K3 U- X    setup-cars/ M! I. b, {7 g, [
    set-car-color
1 M- y/ R4 p! ]' [6 i    record-data
& D  {8 c8 f/ {  ]- ~$ v1 Y: e3 e# t7 \2 `" E8 r
) H' T( P* f! J! Y  U9 B
  ;; give the turtles an initial speed
; k3 T% t9 A+ Z/ _  ask turtles [ set-car-speed ]
$ p* w0 W, |; b3 t  v
7 e( o$ U- {: f; f$ O4 G  reset-ticks
, s3 W3 K9 r; [9 y. L7 J; qend
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;; Initialize the global variables to appropriate values. _) L1 \0 E7 u, T6 C
to setup-globals$ j3 f; y0 A  }. x0 l# e1 L
  set current-light nobody ;; just for now, since there are no lights yet
7 D6 C1 P1 {/ j2 f( ?* z  set phase 0% N) ?+ k" M* v0 X, b
  set num-cars-stopped 0/ t  }0 R# P  \4 H: y# q
  set grid-x-inc world-width / grid-size-x! R2 m% `4 |: M$ O, \
  set grid-y-inc world-height / grid-size-y( e8 u/ M1 L' \2 V: l" s

# s7 ^7 M' j, ^- F+ S  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary) ~, v2 v, L5 C0 v1 h
  set acceleration 0.099
* Q9 N# O' D) m( {/ s0 [end
2 K" ?5 A! p4 r& V8 R4 x2 x+ F/ g& b& R+ C" e* G1 F/ u3 U
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
' A0 x" L; \! f2 G- G1 w) X;; and initialize the traffic lights to one setting
+ D4 x' h$ ^; j+ @: b* zto setup-patches0 t* _. j+ N( T! S
  ;; initialize the patch-owned variables and color the patches to a base-color
  z+ w/ e" @7 Z! F+ N  ask patches
$ F" s" [* o3 {6 K# S2 R; R  [
) w: f0 |8 Q8 k6 C    set intersection? false
: I; Y% x# u; i2 x$ c9 k    set auto? false& v+ m- W+ Y8 L- Q
    set green-light-up? true
0 m' k: }1 d/ r) n! F1 J& g    set my-row -1/ [7 ^  z/ L/ N: F  D
    set my-column -14 j! a* R! o* ?
    set my-phase -1* @' d' F7 u  }' b3 `
    set pcolor brown + 36 O" a. l" U$ Y0 c
  ]
$ p1 B8 Z7 C0 V6 }: \+ I: m& ]+ C( K  H" a
  ;; initialize the global variables that hold patch agentsets+ i- U, p) i8 P0 j, W
  set roads patches with/ V" B# ^; Y$ W/ }. J
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
0 n* j, u/ f, s6 J$ F, [  m    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]) u) d8 c) u+ o$ p# I* s
  set intersections roads with
8 E4 }' V6 P0 v/ u( W    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and0 z$ u# e+ V5 `/ O! L- z* b
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]. f' O, r3 H- o/ H

# b8 `6 h2 G9 e' z1 S  ask roads [ set pcolor white ]( G3 M9 s% Y5 @* A  V0 M: I5 ]' A
    setup-intersections3 p9 V- x$ D6 a9 b% m8 }# {' u9 s
end
4 _/ f* U1 a3 K* m! E0 m其中定义道路的句子,如下所示,是什么意思啊?6 Z& o* M. Y% `# U1 }% p  X) _# K' I
set roads patches with" g7 M+ E) c7 C* t3 z2 K8 _. `
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
6 X$ Z) @7 g% N: \  u6 k" Z# B    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
* _8 F6 W$ o9 T- u& h4 H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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