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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。
8 q" J8 b! u' T7 P  A8 Gnetlogo自带的social science--traffic grid这一例子当中,
: p( n2 I2 p  X5 Oglobals, Z" Y/ f( n2 ]$ v8 v9 g
[! v0 @$ Z4 ^+ u
  grid-x-inc               ;; the amount of patches in between two roads in the x direction, i# n; R4 E3 T6 G
  grid-y-inc               ;; the amount of patches in between two roads in the y direction) o% q# g: F7 k4 F, ~) U2 s  u
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
, k* K7 i2 b0 E! V5 X+ z: l9 _                           ;; it is to accelerate or decelerate
2 c' d) w1 ?8 h. f; T& q0 l( P# j  phase                    ;; keeps track of the phase
; U0 ?) P  }$ t  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure! U, o+ D* w2 @1 q
  current-light            ;; the currently selected light: X4 D. Y1 b1 w  c% w
0 u  _( H6 k  f/ D( R% q6 r( a8 M, |+ o3 R
  ;; patch agentsets
9 j! m/ Y4 z  P  intersections ;; agentset containing the patches that are intersections
  N  `* i) g# B8 v8 d4 ~1 b' N  roads         ;; agentset containing the patches that are roads
& m9 `+ Y: B& M. X0 Q]
# [" O% Q0 B" [1 q2 B! V" {% A8 H1 `& \) [+ ?8 Z
turtles-own
! t. K7 b" {' x9 z$ @) {: G: r[
( `3 O$ j) o1 M  speed     ;; the speed of the turtle( i. x8 @2 E5 [/ A
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
4 w7 w# j. U/ C  wait-time ;; the amount of time since the last time a turtle has moved
, A1 O  [2 _3 D1 f6 i4 i+ C2 h]  Z3 V7 I  M- d* ^. ]% b5 b

" R7 }0 W& B1 p- {1 E( w  t( jpatches-own( D6 c) m4 h3 f6 r" u
[) Q- S% v4 o8 x9 C) k% }# t
  intersection?   ;; true if the patch is at the intersection of two roads
+ c+ H: U3 N, V4 ^  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.! z' g$ d6 ?% ]1 G2 D
                  ;; false for a non-intersection patches.
% d3 R9 j6 O. c5 J6 G  my-row          ;; the row of the intersection counting from the upper left corner of the, B2 L3 F6 G  f8 v+ `! ?
                  ;; world.  -1 for non-intersection patches.
, J6 h4 H+ k% C- g! ^) d! \  my-column       ;; the column of the intersection counting from the upper left corner of the5 o  O$ ^+ X4 [7 {  y' K! I9 a- C
                  ;; world.  -1 for non-intersection patches.
9 o; b" G4 w0 e: K$ ~0 m7 e# Z* N* K  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.8 c) H+ Q( @. K( k/ s2 C
  auto?           ;; whether or not this intersection will switch automatically.& y" o; {) i, I5 `
                  ;; false for non-intersection patches.6 j# L: w( j! {5 c( Z( R6 b
]3 E3 \" f8 y- g& P2 `- R0 l3 ^
/ f$ w$ f2 W' u+ H8 f5 H, n
) l; A! Z2 w9 o0 b$ e7 o
;;;;;;;;;;;;;;;;;;;;;;: e! O8 v$ e8 s+ j, W! N
;; Setup Procedures ;;5 U* I- |8 x1 F
;;;;;;;;;;;;;;;;;;;;;;4 ]. l4 Q  ]% O+ ^" y$ E
+ D& |0 G6 y! J8 B7 a. J( u$ O
;; Initialize the display by giving the global and patch variables initial values.  u9 \4 Z! V7 O7 F; K' m) }
;; Create num-cars of turtles if there are enough road patches for one turtle to
7 j  j! Z7 s4 u; |;; be created per road patch. Set up the plots.  h& Y9 L# C1 D1 J
to setup' T" g; z% G. ?! Z9 s* p
  ca
6 ~# r' z; [+ T5 Y% ?  setup-globals
" c& ]" a6 J! Q4 _9 L% \& v" p8 b# J# G# T! p) \4 B3 y
  ;; First we ask the patches to draw themselves and set up a few variables& i: s, d1 r. n
  setup-patches- K$ w  \# S' E; d
  make-current one-of intersections6 L8 `8 _3 G7 b4 \
  label-current
" o- f7 K' n- |$ L
# P+ {8 s/ t  P  set-default-shape turtles "car"' m& q! h3 L. h; w, `) j# M

4 _1 m3 u7 Y0 n5 ]+ z; f/ M( c% X- P  if (num-cars > count roads); _! E& ~! f/ {- R) T" A
  [3 D: U9 k  w) k! k9 \, q/ Q- ~6 Z! E
    user-message (word "There are too many cars for the amount of "
+ Q8 j4 {' z) P! {! n" b# N0 f                       "road.  Either increase the amount of roads "
: q% {" f% g! L$ J3 R; I% k                       "by increasing the GRID-SIZE-X or "
# C  t$ h1 y, f* i                       "GRID-SIZE-Y sliders, or decrease the "
' g  z3 n6 Q# q& X                       "number of cars by lowering the NUMBER slider.\n"
. U7 \1 `+ ]) ~& Z1 r# i$ z                       "The setup has stopped.")
( ?: O$ ]0 g! O+ W  S2 }  i    stop. G. _2 ~  M5 s4 Q+ r" I2 F2 ^
  ]
+ |  E+ ^: X4 N: P* u0 Z' @* @* B1 Z( x# p
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color9 F# X8 f5 w# p; y3 l% G
  crt num-cars
1 F" m3 g- ]! P/ _2 s& E. P% M  [
# W; b7 V5 J& N+ h4 V9 K, M    setup-cars; e5 f( s' Q5 l$ ]* d% @
    set-car-color
. D( U' H8 H0 y* q6 p6 R    record-data
; a7 o3 w9 G+ e) s. y& K9 ?  ], P& G# S* v+ |' `# P; V9 y7 S7 U

! F, E  J+ D, E) n$ f5 D. q  ;; give the turtles an initial speed- s9 s" @. Y; W$ N
  ask turtles [ set-car-speed ]+ Q5 ]+ o' M7 `! t' f
' F$ h/ f& z9 |
  reset-ticks2 d3 x3 G9 M1 ]+ K5 c6 f& U" P
end
- D: s3 Q5 L) J( p  G
& c; l% B' ]" y4 ~1 c;; Initialize the global variables to appropriate values  _; W5 _1 q. W% N+ P+ U1 L4 Q
to setup-globals9 K: C7 P- G6 U( o  P8 \
  set current-light nobody ;; just for now, since there are no lights yet
! k6 V+ Q& h$ }0 C" T9 A  set phase 0
4 y" c- S- A# l2 b7 `  set num-cars-stopped 02 W+ u8 \9 ~4 q8 t. Z8 b! h3 E
  set grid-x-inc world-width / grid-size-x3 X" B, U; f1 e9 ~
  set grid-y-inc world-height / grid-size-y
- Q- s$ @3 Q6 Z& h* U# i- w; d; @+ |) z
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
% b# A& h0 l1 C5 R; u) `5 m2 `% v  set acceleration 0.099/ D( Z: p- e  k( z; ]5 {& ^
end) {% T, T" Q# j. o2 b$ e* w( I

4 z2 \8 S! g6 P: |- L' Y;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
* a* b7 X1 Q2 A4 l8 {# P% I;; and initialize the traffic lights to one setting; K( v" R8 e/ d$ n8 U0 e6 {2 j
to setup-patches
& I- X1 t6 J: N8 B; p. Z/ u4 A1 n  ;; initialize the patch-owned variables and color the patches to a base-color
8 W; a" I* @- N, p6 l- p  ask patches
  Z7 d4 W0 n* k( i  [
; n0 `6 `# E1 Z8 n3 V" M  a5 D/ k    set intersection? false
! H7 o' h0 U9 w; f; ]0 h/ x+ _0 k6 r    set auto? false
! ]0 w: n* G9 ~3 w    set green-light-up? true
" E! a4 ]& K, u( N$ B7 M    set my-row -1
6 I9 N' j, k& _    set my-column -18 Q; q9 y6 ?* r: d# p
    set my-phase -1
  z* n, ~; H1 V) }' M+ @; y* g, A    set pcolor brown + 3, Y0 p: Q1 E; T
  ]+ M9 b' [+ _9 b! t, U+ }" k6 C* d

" b! G2 b% }1 l7 T$ V6 N, {2 |" F  ;; initialize the global variables that hold patch agentsets
* R  Y* c1 |$ Q" v  set roads patches with
# r  R4 T" |7 M# F; ?    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
4 B0 B- D1 B5 M% T3 J+ g# }    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]6 }9 y' Z! h% t) O2 B" {
  set intersections roads with
' r! L$ u! \; w3 o4 E    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and; E8 w+ z$ {8 n5 R3 i" X
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]! ~5 I' E) i9 d! l! R* c5 P; G
2 P1 C- }4 w1 m1 ?
  ask roads [ set pcolor white ]6 |( l% V- n2 ^, N
    setup-intersections% l5 A! `+ y5 ^0 o4 b" ~5 U9 G. D
end9 c, u0 k6 t% K; h- I
其中定义道路的句子,如下所示,是什么意思啊?; L2 I0 p8 ?& d! T5 b+ F7 C
set roads patches with
, n4 E/ B, U& P    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
1 a+ \& M  i) s7 m    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
' R7 x9 O7 l( L: k/ S. v' @, v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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