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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。
* I/ R' I3 q3 Anetlogo自带的social science--traffic grid这一例子当中,+ r$ ?; t: t3 ]5 O6 s
globals9 L: O) x) _0 u8 c( [
[
, o+ {; S& C( c2 C( U  grid-x-inc               ;; the amount of patches in between two roads in the x direction0 A( I$ q: ~  `/ t
  grid-y-inc               ;; the amount of patches in between two roads in the y direction  @6 H- v: _* V+ M
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
) G5 z# G, b; p                           ;; it is to accelerate or decelerate, F. K; [& ~9 M0 u4 v) j" b
  phase                    ;; keeps track of the phase% y' C* B7 G- k, i/ {2 l0 X) N/ A1 n
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
1 G8 y4 o. h1 r1 j  current-light            ;; the currently selected light
  h, P5 p" s# J1 ^, ?! L/ J" M% L4 a; w( m
  ;; patch agentsets
6 h5 |" z1 b/ ?! d  intersections ;; agentset containing the patches that are intersections. I* `% ]( o4 \6 [( E& _$ T7 _$ h/ F
  roads         ;; agentset containing the patches that are roads
: S/ {6 F3 z. l3 o/ o- C- L4 r& D]
% f! t5 {. R, t! q/ F, D. r$ H( g  r# l& D7 V. E
turtles-own
4 w, F2 e* A0 g3 e% y, Y8 T[# c( ]/ J0 Z% x# e$ \" g5 e3 T
  speed     ;; the speed of the turtle
+ y/ J) J+ v9 T3 @  up-car?   ;; true if the turtle moves downwards and false if it moves to the right, R, T8 V6 @) A4 |
  wait-time ;; the amount of time since the last time a turtle has moved
/ B& l7 @5 L) H]1 ^& q8 f6 g# t3 c5 B+ m

( p4 B$ X1 ?% h, Kpatches-own4 h0 U+ t: u) I# F: y( R1 [! H6 R0 k
[
. u0 D. j+ w! A9 ^9 W; A" N/ p5 D  intersection?   ;; true if the patch is at the intersection of two roads
( s/ J9 v1 ]& x% I+ Y  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.+ ?, \" l: l) @  g- b6 A
                  ;; false for a non-intersection patches.
5 v3 ]9 ~1 Z2 Q+ g4 ?  my-row          ;; the row of the intersection counting from the upper left corner of the
; O7 f% d4 J, @/ n8 g  J                  ;; world.  -1 for non-intersection patches.( P: L" u4 A) {& r5 R- x
  my-column       ;; the column of the intersection counting from the upper left corner of the8 \. q" q+ g8 ^4 W9 K. i, d/ ^
                  ;; world.  -1 for non-intersection patches.  u( B5 x9 d& k" m
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.. }$ n/ B& H" C
  auto?           ;; whether or not this intersection will switch automatically.
% Y2 @$ e; ]% g& U4 f9 a9 A                  ;; false for non-intersection patches.! Y# y1 _8 a; m- `/ [& L
]
7 Q# \; p: Q+ r: z. v( v
+ W; a$ I7 [' M" [6 R: W0 O0 v* l
: E& Q$ d! L6 e3 [% Z/ H;;;;;;;;;;;;;;;;;;;;;;
' l4 ~2 u1 |1 k;; Setup Procedures ;;8 t" d' X2 `$ Y9 V9 {4 d+ G
;;;;;;;;;;;;;;;;;;;;;;
  |' N5 J  Z# I( D' B
. i$ E; B7 a% c0 G0 `7 _$ r;; Initialize the display by giving the global and patch variables initial values.
/ p) u# J- I- [;; Create num-cars of turtles if there are enough road patches for one turtle to
! D% k# |- d- L. O;; be created per road patch. Set up the plots.+ ?/ l- M  f$ @' \4 D
to setup
. }. {  W4 Y) T: ?% V0 Z$ Q* I. V  ca+ Q- L6 W" N0 |) c; W0 C+ R
  setup-globals. O: v3 ~, ]2 p8 }  s# t
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  ;; First we ask the patches to draw themselves and set up a few variables0 q5 n7 c7 f& b5 k1 Y1 A- x5 w& F
  setup-patches
% I9 X+ M9 _1 u# E3 _  make-current one-of intersections
- n3 e5 n- ~8 @9 p  label-current
# ]+ v) f8 Y- K  a3 V) e( H. B& }. `3 R' i0 T6 b
  set-default-shape turtles "car"" E- x5 m2 Q3 @- n9 d, S9 p  f% k4 l7 m

$ m8 Q- U" U6 s4 a+ Q: E0 l  if (num-cars > count roads)
3 a9 g' d, M$ G, ]  t9 r  [
) i  q3 L" ~6 @$ A$ x9 U' s9 _. g. S    user-message (word "There are too many cars for the amount of "
, l- e" j1 I8 e  s                       "road.  Either increase the amount of roads "
& G0 ~0 D  m* `, m; a                       "by increasing the GRID-SIZE-X or "
" n5 I9 @. F+ K! ?) B                       "GRID-SIZE-Y sliders, or decrease the "
+ M- j, P; X3 n, \& T! L                       "number of cars by lowering the NUMBER slider.\n"
# @" P" A5 o, B                       "The setup has stopped.")/ O! S5 J/ v+ `9 W$ x
    stop
2 A& b% ?, W; h# ]$ X7 M. \6 _  ]+ }5 t; g: ?4 M( l5 j
! Y( ]2 Q5 }/ a. q2 e  I6 p# o
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
' F, y2 k8 D" ^  v7 i  crt num-cars
3 j( o- ]4 [0 `/ x2 c  [
8 K# }2 X) S! G$ f8 B    setup-cars
1 P: P0 u( ^# b- x/ O    set-car-color
4 E- K+ p; B! n3 E/ }0 R9 V1 v7 y- i    record-data: W  _+ {  c8 c) Y4 Y$ \5 z0 F6 ]
  ]+ A* t. w- {" |- E* ]- k& J

4 ^  @! o; c# t1 M% C, Z* W  ;; give the turtles an initial speed
/ a; J+ p; F1 o. s; O  ask turtles [ set-car-speed ]6 m. U" L- y  L: Y1 B* a

6 T% z& @4 i0 y4 I; z/ L, m$ n$ f4 J  reset-ticks) M! v% s( b8 _2 v6 e+ b: g
end
7 X4 q! Q4 i$ J- y! ~* s- U$ i# r% z9 u# \: O# S8 e
;; Initialize the global variables to appropriate values. l/ Y; Q7 S5 S: y" L/ I* M, g% }' e
to setup-globals
/ a  H: d6 E" C& X  set current-light nobody ;; just for now, since there are no lights yet
2 o( A" A, h7 c2 H5 z+ K: ~  set phase 06 F% ?- K1 V/ [- _  X0 O+ @1 J
  set num-cars-stopped 0
3 Q$ h& Q8 K2 ~7 W5 O" I  set grid-x-inc world-width / grid-size-x# i' G2 G7 U& G. S/ r" ~; x- \# p
  set grid-y-inc world-height / grid-size-y
- n7 t* ?! k( j% t4 W5 a0 V6 v! _4 t' b1 y8 ~* L
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary6 S* Q7 j$ h! ?8 O- A
  set acceleration 0.099
/ Z9 }1 F3 o# g% H1 M4 Dend
" k7 @6 }: V9 X& Z" X5 U; j- i8 L& Q8 x( z" d! q( `" P$ P3 V
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
6 @, q1 z) S' E- K0 i# E" w;; and initialize the traffic lights to one setting
' j- ?; j- @/ i0 V- O% b' @to setup-patches3 t% G: L1 w  V1 u2 C2 p3 [
  ;; initialize the patch-owned variables and color the patches to a base-color  p, @2 [+ s" D% M0 _( b0 X, w2 e: J2 h9 `
  ask patches
1 x7 ^. v+ P8 F' w5 R) k' E9 `# W  [
; w  c1 e& x$ J2 ~) u3 {, N    set intersection? false
- N/ L7 A1 W$ n1 G    set auto? false
8 c* A0 I2 Q! x% u, G. ]9 g6 U( N    set green-light-up? true
. [5 [& N* Q% B5 c0 y  n    set my-row -16 y* l' L1 `, O
    set my-column -1) K3 H; h7 B  \# a# n: Y
    set my-phase -1. t4 i6 p) I+ v! L; G' L8 r. i
    set pcolor brown + 33 i5 R4 T' }( U2 P$ `# R
  ]6 P8 l% A- s) g5 q  j7 H, a
4 V0 ~+ ?1 |. i, F% J) S
  ;; initialize the global variables that hold patch agentsets7 N% P9 n% M& O3 \! N
  set roads patches with; p' `6 N* V6 q9 `# D) O. a! h9 L
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
8 [  c7 R# n/ \1 A* z0 |& B7 N& n0 |    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
9 {8 ]3 {8 g+ W8 I1 |6 X3 q3 q" B  set intersections roads with
7 s8 k) h1 f% Z2 ?5 S    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and* [' K9 g- ?: u3 j# Q- D: \
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]' B/ F9 S: g6 G4 ?. N

- [4 Q' T6 _8 ]* |5 M1 ^' t  ask roads [ set pcolor white ]
# W- b& r0 I. V9 z7 P1 D: G8 V7 \    setup-intersections
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其中定义道路的句子,如下所示,是什么意思啊?
4 A; @4 T# _' P  o% u: p& H' ^ set roads patches with* s3 A+ ^' l8 @: Q* X/ m
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
- N& D/ I5 t. A* D. r& Z0 ?    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]; p0 W$ f6 u- h! l  I4 o/ w
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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