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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 Y3 J% |- }' E8 k% k! _0 D) ?6 H
netlogo自带的social science--traffic grid这一例子当中,2 T, f  U6 z' U. y9 ~+ n' R( v" o
globals
% f; G, h9 S3 u( J( F' L[; g9 ?: u/ j8 _4 I1 D5 y/ z" j
  grid-x-inc               ;; the amount of patches in between two roads in the x direction) w* U+ g& K/ S( ^" d% Q
  grid-y-inc               ;; the amount of patches in between two roads in the y direction6 Q5 R/ b( p  }9 w; n% d& E8 `# ~
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
# S$ G4 T/ d1 l. o# P4 a                           ;; it is to accelerate or decelerate
, O) h' B$ G  L: W1 ^  phase                    ;; keeps track of the phase0 x0 A7 S, L0 T* E3 b
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure5 ^1 m5 Z0 `* ]# h) E1 Q# c9 n
  current-light            ;; the currently selected light5 m9 P" b7 n/ {+ H4 c
6 }8 _7 c4 U, y  E5 t
  ;; patch agentsets
3 D4 G5 N3 T6 ]& }- j  intersections ;; agentset containing the patches that are intersections
* h4 d  g0 a8 \: x& I" P  roads         ;; agentset containing the patches that are roads) o* q3 ?4 s1 _. m& b0 W
]5 J9 D6 t3 w8 o6 e
6 G) }! z: z3 i  t
turtles-own  B0 E6 a4 U& v  V* C  ^- v
[
! q5 o1 E5 p/ Z) }( K0 _* j  speed     ;; the speed of the turtle3 U/ y: B' h& t, [
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
7 ^1 b  v- H# u* U1 Z; @' J; F; h  wait-time ;; the amount of time since the last time a turtle has moved
! w9 h; J. }5 K6 @+ Q- p]
4 L+ s* A# L' O
# Y- M! A0 `; Epatches-own6 ^' ?' q) e2 Q3 a4 J: t9 F+ m$ Z
[7 |  m' `& Y5 R
  intersection?   ;; true if the patch is at the intersection of two roads
& h) J8 C% W! h1 _9 H4 W  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.2 o0 D# [/ i; x) [9 j7 M- j
                  ;; false for a non-intersection patches.* J; U5 ^/ Y/ N8 b
  my-row          ;; the row of the intersection counting from the upper left corner of the
5 x! r1 U; d" H3 t# |                  ;; world.  -1 for non-intersection patches.# ^' I3 o' [( V6 p0 V, [
  my-column       ;; the column of the intersection counting from the upper left corner of the0 ~) Q; j* R2 }# f5 J
                  ;; world.  -1 for non-intersection patches.2 z0 u5 S( j# ^0 C' G
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
$ a5 a, I; p- l  auto?           ;; whether or not this intersection will switch automatically.
; s9 f# e" _- L: s                  ;; false for non-intersection patches.
  K9 j3 F* ?* v! I]2 p: U: x' u6 a5 O4 e
! p" E% r3 p0 U. R. ?' N, ]

$ N. r1 O2 ]' x- }- U2 r4 _. x! S;;;;;;;;;;;;;;;;;;;;;;- i2 C- Z% }3 \8 U8 Z  f
;; Setup Procedures ;;0 i& N& M/ [- s/ p
;;;;;;;;;;;;;;;;;;;;;;* V5 e: P8 `, D5 e

3 ?2 A$ v+ R8 O2 \, r;; Initialize the display by giving the global and patch variables initial values.4 X& \% U0 X! d9 T; p
;; Create num-cars of turtles if there are enough road patches for one turtle to+ o! G1 K$ j  I/ G) E
;; be created per road patch. Set up the plots., N% T" r8 x$ q% e2 F9 a
to setup
* Z' o/ U; E" }/ k8 R2 K2 K: H  ca
; o7 _; X/ i- Q/ w6 d  setup-globals* W4 |" L1 @% v' w$ M* W

9 ?+ y) f  l  M, g& B/ h  ;; First we ask the patches to draw themselves and set up a few variables% O) |# I$ Z! J' I5 K4 y' _
  setup-patches
% S% a- K8 g: d% y  make-current one-of intersections- p  F, a, A- }4 i6 R* A, }
  label-current
" E7 g% R- V2 a/ ~9 W. _3 s: U. M/ r2 b- h2 _4 T$ r1 Q4 V
  set-default-shape turtles "car"
8 G" e1 W" M# }* U
# E- W' c3 Z) Y4 N0 v# b  if (num-cars > count roads)
8 o. p! a' O& S! y  [
* K2 F+ o% u5 O    user-message (word "There are too many cars for the amount of "
/ {4 v, l! O; c: t! C( E, N3 U2 x" n                       "road.  Either increase the amount of roads "
7 w$ M5 a  y5 I8 D                       "by increasing the GRID-SIZE-X or "
3 t- i2 B& E, q) p( g                       "GRID-SIZE-Y sliders, or decrease the "
- E$ J" g6 D2 q! U% G                       "number of cars by lowering the NUMBER slider.\n"* }. |$ ~" f# H3 L
                       "The setup has stopped.")+ S1 v/ A+ G& _" x& I3 j( A" M  [
    stop
* i0 y; Q. m8 U0 k! C5 |  ]
! |+ U% i9 N" J) @0 y1 h5 I/ m3 t2 ?! {& X# D2 w" d
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
+ _2 a; C* r) r; ^" X" u  crt num-cars& P% J; B7 g. Y5 h- K
  [
" b( |/ g6 t7 ~( i    setup-cars. X* J" Z! Y" b$ J2 H( a! D
    set-car-color# A- B4 Y* f8 h/ l# z1 T- {8 O
    record-data
! r0 e8 _, x/ [- D  ], g$ u0 n* v& M5 c, E) M( S  ]

! K& V9 T8 \" [9 X* n; T  ;; give the turtles an initial speed( h: o& K: w/ \
  ask turtles [ set-car-speed ]
# Q: g! `# D' J' E' X
, t) ]# o9 d) N8 I6 s  reset-ticks
/ P# T2 m( {* x, O! n9 J6 i. O5 F$ gend" _$ k; j! c0 o3 v/ B
% r& `- ^( b5 I, R
;; Initialize the global variables to appropriate values' O- \0 B! H9 N) y" {. P
to setup-globals
" u& f- R8 D. T6 _  set current-light nobody ;; just for now, since there are no lights yet$ s9 U6 m* u; b% [* ~6 `' N8 B
  set phase 0+ S  l7 F/ B1 p; a3 p4 W3 `
  set num-cars-stopped 0/ ]3 @! j  k1 w- V
  set grid-x-inc world-width / grid-size-x$ w4 s  A7 C7 S; A- G9 R4 _9 H  j
  set grid-y-inc world-height / grid-size-y
- P7 r3 q! K+ o1 U/ s
3 W4 u( y% k+ ~  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary% k4 S& l3 B( i7 S
  set acceleration 0.099
& Y3 `5 p- m  [1 X- E4 Jend
- k$ [  I6 `4 L* k- c, e9 ?3 P4 S$ U, o0 W( j
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
: l, o! T/ ^8 s( h, c0 V3 I+ g;; and initialize the traffic lights to one setting
0 z. I8 T4 h% W7 z. ?to setup-patches8 y% Z4 H+ i5 p7 B: L: f
  ;; initialize the patch-owned variables and color the patches to a base-color& }8 K' ?  {! \7 W0 C& I4 q
  ask patches
1 D( @  Q- r4 e" r; W! O, X  [
; g$ H. Y6 R( l' ~    set intersection? false& p3 n; i/ }  V0 }
    set auto? false- z2 c% X$ Z4 E" e% `1 G! Q
    set green-light-up? true/ }+ b) s+ ~: X7 u8 M6 v% o9 N$ k
    set my-row -11 F. O$ u! f! i. I: N" y2 ~
    set my-column -1
  x' w6 f9 d- J+ R    set my-phase -1& j% }. v/ O4 C  i  M: I- X
    set pcolor brown + 3
. k% r) H3 q  U; C0 Q# e  ]
( x1 K& r# y' R: E3 R  H5 K
' L1 ]/ P, Y; C5 n& f/ o  ;; initialize the global variables that hold patch agentsets3 q% P$ m& D7 ~
  set roads patches with
4 C% q3 f# o8 `1 ]4 i) y- K2 Q8 M    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
9 {- n) r+ E$ ]1 w    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]: W3 B8 R7 W0 U$ @. C
  set intersections roads with; T, M" j( _: L; t9 O. P! A, R
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and+ f# @; ?6 C0 h/ G# j
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]/ l! }. }4 _. @: @, O3 R( w9 i# s
$ a) c5 o% P3 T8 T9 ^0 G
  ask roads [ set pcolor white ]5 x: j. c6 F! l* N/ ~
    setup-intersections
3 h8 u" b0 c# S7 C' U5 k- q+ T3 Send
/ c3 s; y( x9 Q, |( ~其中定义道路的句子,如下所示,是什么意思啊?
+ ^1 G, L) Y+ }- [ set roads patches with6 V2 H, C; Q1 r1 E
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or- ]. }: a. o! q/ y# d4 O
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
$ n( i6 N6 {6 U& |6 u0 i! Z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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