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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。- w" T# y" J- I. }8 M: [
netlogo自带的social science--traffic grid这一例子当中,
! p3 ~1 T+ _, \8 zglobals
4 Z4 n9 X$ [9 ]* c& ?[! s5 P" K% J3 {" V# H
  grid-x-inc               ;; the amount of patches in between two roads in the x direction: i/ \# J& `6 S+ v5 V- o& K9 P
  grid-y-inc               ;; the amount of patches in between two roads in the y direction' R* _) `$ m9 L5 \( G4 c2 ^
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
7 ~4 P$ [% Y/ h8 K5 N1 Q+ d( [! m                           ;; it is to accelerate or decelerate3 X5 P1 \8 Q6 g, h9 v0 A
  phase                    ;; keeps track of the phase9 V9 }( J8 d% G, y8 z9 ~
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure4 |* _& q' j0 J- u# q4 F' w) b- V0 H
  current-light            ;; the currently selected light# I  p. o) T; f% ]6 z
$ J2 ^- N& ~, o
  ;; patch agentsets
$ s5 ^! A/ O/ a0 A& }- d  intersections ;; agentset containing the patches that are intersections6 M6 r, `! V1 ]( Y7 b! W
  roads         ;; agentset containing the patches that are roads
9 @  g. Z' P6 A5 f]
- A  x$ \+ h, I! c% O) _9 q/ P* q/ h$ Y6 D6 F+ H1 i, S
turtles-own
8 l: Z5 o/ g  c7 ^. D' A1 M, [[9 d) E' w/ j. p
  speed     ;; the speed of the turtle0 h) ~! C8 f* `" O$ K. ^0 ]) h+ r- Z- d
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right. G$ Z6 A% W) s; l7 i3 }
  wait-time ;; the amount of time since the last time a turtle has moved
3 @5 o; K5 I* l]
% c# v3 P/ L$ F
/ f( E5 _. H( M' ^# Qpatches-own1 C  F! v/ N& L+ m
[
" ^/ K% B' q( a: t. k. x3 Z% n' {3 ?: d  intersection?   ;; true if the patch is at the intersection of two roads
! K3 b) p/ I; j5 X8 n8 E  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.. @$ |$ o1 C: j" z  r+ i
                  ;; false for a non-intersection patches.
+ z# \* w& v' A  e$ f; M. W( p  my-row          ;; the row of the intersection counting from the upper left corner of the
' F  H9 s, k% g" Q0 ^) _& F: p6 K$ [                  ;; world.  -1 for non-intersection patches.! Y2 {- U! P* b! q2 [2 U" `% J  Q+ c
  my-column       ;; the column of the intersection counting from the upper left corner of the
5 `9 f5 F% @  n" |: u                  ;; world.  -1 for non-intersection patches.
8 X- `" a" k5 u- l- P; r  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.0 c" H) G1 k! L
  auto?           ;; whether or not this intersection will switch automatically.! d# h# t5 z4 e1 P* b
                  ;; false for non-intersection patches.
5 L" N: w, N+ t# n; Q; N]
6 ]* K5 N$ A9 v8 o4 A0 n# ~8 Y% W, m# @" E. [

: c+ m5 X" M- m;;;;;;;;;;;;;;;;;;;;;;2 G% j8 O8 Q  \8 Q' [# P
;; Setup Procedures ;;2 n' ^4 k) w3 S: E# R" Y" {
;;;;;;;;;;;;;;;;;;;;;;
* H* Q; R. n) H1 r7 L, _: d. E: K3 |8 J! |8 `
;; Initialize the display by giving the global and patch variables initial values.8 u9 c3 A$ Y0 X: C1 g! t
;; Create num-cars of turtles if there are enough road patches for one turtle to( a% c6 m; N8 D7 l- o# N+ v) \
;; be created per road patch. Set up the plots.
9 A: Y* D, r7 K' ^; n0 [& \to setup
' C4 @' E+ E3 u7 q+ b+ q# {$ Z. f  ca, Q" |1 g: ?1 z8 P
  setup-globals8 k6 K5 \1 Z3 C% \

4 h- }( f. }4 ?* F1 S& E' W3 ?  ;; First we ask the patches to draw themselves and set up a few variables
0 ~" w! y; O$ X  setup-patches5 z( F1 x' Y7 `2 v8 B
  make-current one-of intersections8 O+ v0 J0 M  `: C( d7 e( Q
  label-current7 d* H' ]: I" m
; s4 P% l1 u4 k9 X) |6 {
  set-default-shape turtles "car"
5 }( [, X$ u- X+ {! h# g" D
& f3 n9 n* U, L! ?' g8 ~4 I  if (num-cars > count roads)
. V% P7 @6 t2 y0 U3 v8 p  [( U0 g( b7 \1 e" p
    user-message (word "There are too many cars for the amount of "  U+ A$ m- t. p/ C' `) f
                       "road.  Either increase the amount of roads "! Q& B% L; w1 [
                       "by increasing the GRID-SIZE-X or "8 K- Q: j* C" N6 L) I: H! w" E( K
                       "GRID-SIZE-Y sliders, or decrease the "0 D8 H: C; M% R3 J3 W. u+ ^3 x1 }
                       "number of cars by lowering the NUMBER slider.\n"  b$ [* Q( G* N, M' {1 v  D: G
                       "The setup has stopped.")
- d( W/ E+ C7 h9 R3 E( H2 z    stop
, k  _9 g' F' t  ]. }1 I' C: |( P. C% E
- \% H$ y! |3 u; l% [5 ]
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color! o$ y7 @" Z) Z3 m1 M+ L; m' R6 c
  crt num-cars
. B; |0 `2 N% U3 R0 l7 j3 K  [
, G* ?1 _( g0 d0 b+ n    setup-cars
8 I/ N4 P; R' x    set-car-color% o2 M$ H9 W8 h% Q) H2 A
    record-data! \2 i; I( f8 X; X
  ]) g- h/ ^7 N, ]" v1 V8 ]: i

# a8 t, Y3 }% U6 F  ;; give the turtles an initial speed
; {3 ~& a2 V* H; F  ask turtles [ set-car-speed ]6 |5 ~3 q$ G% d  z9 ]
; x/ ?7 ]% A: d
  reset-ticks3 F* Z. r; d+ Z. w8 H6 R5 p; L$ g
end: I% j( z  H1 K; A* G" w

2 L# Y; A- a+ g  @4 k;; Initialize the global variables to appropriate values
3 }* b% x) q6 ~) A/ dto setup-globals
* ]* p$ s3 P' B1 ?6 \+ C  set current-light nobody ;; just for now, since there are no lights yet7 I( O4 D7 T; s: H
  set phase 0% A4 t. z! K  K' U' Z
  set num-cars-stopped 0
$ a) B, {2 Z5 E* H( o3 o9 G  set grid-x-inc world-width / grid-size-x
  f2 m1 u- Y4 G# t3 B$ N  set grid-y-inc world-height / grid-size-y& k+ i2 `! G# Q) b( R1 ^. ]5 i  q5 L
  ]- X/ P- S9 N6 G
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary$ S: }9 K. n0 d8 F: p# s
  set acceleration 0.099
, x& F+ `! j" r: G/ V) Oend9 r" ?8 Y  `( \2 |; t

' a! H, Z  |  q;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
; x0 Q1 |/ d$ X;; and initialize the traffic lights to one setting
5 f) p5 `; m9 E3 y# r; }to setup-patches- B9 ^& ]& l3 A$ g' y" u
  ;; initialize the patch-owned variables and color the patches to a base-color
8 ~8 N$ H! B5 d' C  ask patches9 p# G1 Z2 N7 k5 P3 {
  [+ N: w, b  P% _
    set intersection? false
+ ?: C: O) ?  T" w$ Y7 n% M    set auto? false
2 q8 h- m' q6 o& K, y+ `% F8 {    set green-light-up? true
# ]$ f" \! [" H9 f' D  `0 D/ t    set my-row -1$ ]- s4 w8 O' q/ Z7 F/ U4 u$ w- @
    set my-column -1
' i& A5 Q+ g+ ]. Y$ d% G    set my-phase -1
! p9 [8 A/ q% Z' I3 f4 M    set pcolor brown + 33 l0 I  q3 N9 Y7 T0 n
  ]6 T- o/ f/ B2 ]  m9 v

" Q* W! e9 t$ q* I  ;; initialize the global variables that hold patch agentsets
; @8 ~+ r  a# C* w  set roads patches with
7 R1 v. Y) M# I5 A# |7 K    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or8 c- z1 Y7 Q7 [* u9 n
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
& F" Q3 U$ O: |( K) z* b1 |  set intersections roads with
, C! I& a6 J2 _+ q6 B( Q1 @    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
( O+ k+ ]2 L7 D/ ]    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]: C. z  x9 e( s; a( H- z3 `

) y+ P8 s# j0 j  ask roads [ set pcolor white ]
! V( K/ Z* W3 p$ ?0 U% r" F7 m    setup-intersections) r5 m( P5 }2 G) @
end1 k  L' C+ Q& W: l
其中定义道路的句子,如下所示,是什么意思啊?; T! `) X% |, o2 h+ b, J  M  }& m
set roads patches with! I, ~- X+ D" L* w3 g3 R/ [
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or# v  ^, @+ [: ?" z8 Q& {& a8 x
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
: k# o( `+ d, 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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