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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。4 b2 a# ]  ?7 i" v' T0 \
netlogo自带的social science--traffic grid这一例子当中,1 M. w( p& N/ _  G* X0 [
globals9 ?4 c$ M  b) B# y9 n6 F! q
[
$ \/ O0 t6 _2 V8 h  grid-x-inc               ;; the amount of patches in between two roads in the x direction
! [% }  w1 g* O0 {  grid-y-inc               ;; the amount of patches in between two roads in the y direction
; S: r. c/ H% P) ?$ p, {# v: k4 h/ x+ Q  acceleration             ;; the constant that controls how much a car speeds up or slows down by if% r' s9 v( y) k- x
                           ;; it is to accelerate or decelerate
2 ^+ k7 r# D( {! f) p# |) N  phase                    ;; keeps track of the phase
: K& E* A8 D2 X, n- U; e) W! d- m' x  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
, {1 D; u* R1 i$ {, T2 ~( f  current-light            ;; the currently selected light/ J& C  \* u" j( r1 m8 n

9 `  P( r7 w7 B  ;; patch agentsets
3 N' O1 V5 Q: C9 ~0 C) r+ k  intersections ;; agentset containing the patches that are intersections
' x: x& D9 Q5 V& H2 o  roads         ;; agentset containing the patches that are roads8 i" ]  F0 J. D# I; i
]
6 n4 u2 W8 U# W5 e% Q5 ~- q. @- ^- N. ?+ O$ n# Z" S+ U
turtles-own
0 J* M; \+ T: Q% K8 e7 i[- U. `1 B; W: ~( h/ `
  speed     ;; the speed of the turtle
0 A* I* E: R& q: c" P8 J. S  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
0 g2 l7 [, n/ }5 I  wait-time ;; the amount of time since the last time a turtle has moved% r& E! {4 i: Y2 z6 X& K
]8 Z! e, f/ F) H. B6 u5 _4 s
, Y5 U1 {5 m: r( [
patches-own
7 r3 y* N9 e/ ~  q* d/ I1 v[
; A& T5 F& G: A" H( L  intersection?   ;; true if the patch is at the intersection of two roads: F3 l/ P3 ^$ ]2 _! b& {
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.  x# |3 y- K. L; I
                  ;; false for a non-intersection patches.3 h% v* Q' j1 v4 F
  my-row          ;; the row of the intersection counting from the upper left corner of the
4 A! l1 M9 X$ W0 t                  ;; world.  -1 for non-intersection patches.
$ u/ o9 x. g; U! f  my-column       ;; the column of the intersection counting from the upper left corner of the
" h) q! o( h4 y, ?! e                  ;; world.  -1 for non-intersection patches.2 Z6 [4 a# b" N. Y- A4 Z- k6 k/ b
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
3 ?3 o2 u- U8 d% z4 ^& x" `+ s  auto?           ;; whether or not this intersection will switch automatically.
( R1 |/ w; }0 r9 g2 L* L                  ;; false for non-intersection patches.
- d/ J$ x; e6 i]  P2 \4 I: S! {9 W8 X) H

5 j0 ~$ v- c! n6 D% ^6 M
7 T) L- f' C8 d! x;;;;;;;;;;;;;;;;;;;;;;& h. _/ w" v" {) g; J
;; Setup Procedures ;;
5 F2 B6 _) \2 D;;;;;;;;;;;;;;;;;;;;;;
5 x' X; q$ K0 C1 b7 a) y# x5 v( c
; \- N3 o  }& F8 I. |;; Initialize the display by giving the global and patch variables initial values.
: Q$ t& c; {" G0 Y% Q;; Create num-cars of turtles if there are enough road patches for one turtle to
6 ^* Y) x) |1 N5 e/ M. \. ];; be created per road patch. Set up the plots.
/ R# Y1 @$ v& n& [$ K1 }to setup
! C. s& M# [8 N  ca
/ f% ^: q) }$ X& Q6 C$ D9 `  setup-globals$ b" f" \0 D( h* a3 Q

; k' S: k9 q0 j  i' s+ F  ;; First we ask the patches to draw themselves and set up a few variables) V2 f; _9 s' B. k/ `# @6 s
  setup-patches/ w! O5 @" U, n9 B" K; w0 ~) q
  make-current one-of intersections: x8 `7 y1 E: E/ A1 K1 j
  label-current
6 S0 q) K% q# ~: H' o
( D2 H9 j" w' ?3 m  set-default-shape turtles "car"- d' p) T8 i$ j7 d3 p0 I# }0 o( p
9 a& S% |4 Z9 {; P/ n
  if (num-cars > count roads)
' ]% X* Y" \( |, K' f  [
9 Z5 N. O* D( E& U. g- b    user-message (word "There are too many cars for the amount of "% q9 {& R+ B( q1 _* S7 n3 J3 U
                       "road.  Either increase the amount of roads "; M+ Z8 S" N7 F
                       "by increasing the GRID-SIZE-X or "0 _5 y# @8 C/ g- n* F/ B1 D# T
                       "GRID-SIZE-Y sliders, or decrease the "
, @5 r  C0 q/ p0 |. Y6 C2 k                       "number of cars by lowering the NUMBER slider.\n") K) V0 u: o' n  A
                       "The setup has stopped.")  I( d& S8 m- A4 f- O( {# e
    stop& |, F$ e) g, k" q4 H
  ]6 N; C6 k: S7 e0 p% m; [& f

/ j# j9 a& z: K" {  w8 i  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color2 p8 o5 W6 w+ @/ f
  crt num-cars
, o/ s; B$ w' O% f  H0 Y' F  [& J! G) s3 o. y" ?* o
    setup-cars$ w- I6 V% \/ ~4 ?: h! @1 m
    set-car-color
5 R: ^0 E. d9 q1 T' @    record-data3 C9 B# t# K' w# m% B; U
  ]( V* |/ {2 y5 e# c

. ?" r. O" _- R6 O  ;; give the turtles an initial speed: {. z7 R% n- b" p3 ~' T
  ask turtles [ set-car-speed ]
, W- s( y% @' _) x" X+ y  |) ]+ `3 g" `$ j& g- ^# p
  reset-ticks
9 C& P3 k+ W& x) k- k  f+ Mend' C. x6 Q4 v. G1 o6 @
- }2 n; v8 k. Z5 ?5 y: s
;; Initialize the global variables to appropriate values/ n* h6 ~# l8 i5 Y
to setup-globals6 E' F2 H( P: z4 Z$ c3 |. [
  set current-light nobody ;; just for now, since there are no lights yet
+ g2 _# g+ {3 {1 V3 t# C! H. K  set phase 0
" J: O; ^4 ?8 R; z, n  set num-cars-stopped 0
2 O& |* v3 T  q# M- v/ S' T2 L  set grid-x-inc world-width / grid-size-x# ]+ a% y! V1 V- I/ A* w  l0 A
  set grid-y-inc world-height / grid-size-y0 c( ^+ S9 \6 N% U

/ _% ?2 |3 V7 k4 @/ u$ J  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary( k: `) h. _+ E! }1 ]
  set acceleration 0.099! d# b! b8 T+ H" K4 ^: X& `
end5 F9 w5 H6 e* R; t- D2 g
6 ^5 J0 x0 i  T/ x/ f
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
; X$ T/ w1 W7 B;; and initialize the traffic lights to one setting
, V% ?$ P9 p" M3 Pto setup-patches
3 u3 H9 h" h. N5 q# j- d  ;; initialize the patch-owned variables and color the patches to a base-color
: O4 O+ m3 t7 I7 o, B1 Z  ask patches# c9 b$ d: c- a) b: @9 I
  [, U5 k- n0 v# u# F/ b6 E
    set intersection? false5 i" l; ~" \* x- D8 |9 t
    set auto? false4 o( e0 o" T& S; C: @3 _8 |6 s) {
    set green-light-up? true
/ I9 r+ [5 ]: `% ?    set my-row -1+ M$ W; R' Y1 r: ^2 _4 q" ]4 b) y
    set my-column -1
: F7 a5 t. E. Z5 c    set my-phase -1% `: l( U3 }" H0 {! H5 g& G+ F/ }
    set pcolor brown + 3: \6 k% J; V: i2 V
  ]
: @: v  ^& Z6 a4 Q; h/ C9 F" r  `3 ~: G
  ;; initialize the global variables that hold patch agentsets# s$ T/ {) A/ g) r" P* s
  set roads patches with4 O' W$ M8 J, W/ G& D
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or7 `8 ?' m- h7 h
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]# w( G" O1 h/ ^( s( E  J
  set intersections roads with
" P! M! n( j; b; s/ s" Z% a    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
' K: i: W  V% F# q1 E    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
7 \: C8 n* {# x( i4 T; v9 H( a- `- f% J  F8 R. S
  ask roads [ set pcolor white ]
& ~( [1 c0 t9 @5 D, w5 G" S    setup-intersections+ A0 V# u  M3 ]+ F
end
% O0 }: c* {9 k其中定义道路的句子,如下所示,是什么意思啊?: _2 s# s: B7 e( A+ M
set roads patches with
- j. B8 K" w- [    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
4 w" r: c, |" A! y; S% _    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
  O' e7 f/ O* I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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