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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。
( s" i/ m# [  e5 Rnetlogo自带的social science--traffic grid这一例子当中,
# h. x* E% O* g! f0 G1 `) m/ Rglobals
* u: l) K2 s2 N% D( |: N" r' B[0 M7 {" E9 s$ U5 K4 z- ^
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
/ z, Z7 u7 J  D. c8 p. t  grid-y-inc               ;; the amount of patches in between two roads in the y direction( X2 W: Y( c7 k. C: }5 ]& T
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if4 G7 b* L- P( P$ j3 K! D: N) W
                           ;; it is to accelerate or decelerate) z$ U+ |) h- ^# y5 k7 C. r- {6 I
  phase                    ;; keeps track of the phase. w* ?' r" F* F( a- t
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure7 @) K8 U; V( N
  current-light            ;; the currently selected light
. N& P- M2 W1 M8 i3 W, q3 U
5 \* Q& H5 O" H: e6 v: o9 v0 ?  ;; patch agentsets
, |$ F5 x  [$ @# i5 a8 l# Y  intersections ;; agentset containing the patches that are intersections
4 ]0 }# \$ @% L, v) a& `  roads         ;; agentset containing the patches that are roads1 g6 `; Q, h2 l7 _& b
]
  z6 n# P7 a6 t
+ U6 N8 }1 O* f1 _& n$ ?+ nturtles-own5 o, B+ R! r2 @1 _) i( T/ k
[
7 A) @8 q) C' w4 T; c  w- x/ _  speed     ;; the speed of the turtle+ O9 B, v6 V* S7 d: Z, m$ ~! q
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right; `2 f0 q1 }. Y, g
  wait-time ;; the amount of time since the last time a turtle has moved
. Z& T( w. |) `]9 T; V3 r, ]) W
" j) f3 T/ l" t$ }- p4 L( h8 t, t
patches-own
* V3 Y, m4 {/ o& X, ?1 D. I+ N[' _  `: [2 X4 ?3 F
  intersection?   ;; true if the patch is at the intersection of two roads
7 W9 `2 V3 K" Z/ ]8 H$ s  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
/ M; t8 X1 N: p4 J9 Z# J3 W                  ;; false for a non-intersection patches., Z4 p: k) b$ A" Y& y9 F
  my-row          ;; the row of the intersection counting from the upper left corner of the9 I3 ?/ K2 ~- l0 m# E  T
                  ;; world.  -1 for non-intersection patches.1 d- o( P( j' h0 k
  my-column       ;; the column of the intersection counting from the upper left corner of the
) i% z( P3 l' X/ v" J8 h( \- q0 q                  ;; world.  -1 for non-intersection patches.- g7 q0 s" M/ R* ?4 i8 u. e
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
7 f( ~7 Y: X! b3 _' y/ N. O% j5 P* |  auto?           ;; whether or not this intersection will switch automatically.
5 G5 c8 l! z( V, x; x                  ;; false for non-intersection patches.
  p, ]/ M+ a0 {& V. d/ Z]' }# r) L' P, o

/ h+ I/ t" Y" W1 u, k$ `: P, a; N! r5 M6 M: w2 |3 O) U0 A) X) O* |/ j
;;;;;;;;;;;;;;;;;;;;;;7 i8 G1 P, i$ ~$ X2 O( d
;; Setup Procedures ;;
2 m2 k: C' e) q$ R;;;;;;;;;;;;;;;;;;;;;;
1 y* M- p# c9 c# l& O' p2 l5 |, d2 B& Z; k6 y2 ?
;; Initialize the display by giving the global and patch variables initial values.
" X3 Z; g3 B% e! f( C;; Create num-cars of turtles if there are enough road patches for one turtle to5 c! ]+ N7 n; [
;; be created per road patch. Set up the plots.1 v' [$ l' C9 b+ ?
to setup$ h7 u' ^7 `- K1 z) R0 W, Y
  ca
7 m; G9 m$ a) s0 ^: A3 U4 T  setup-globals
' T4 X7 j9 }" J$ a6 k* u
3 H0 q/ H( ~  E' n% C  ;; First we ask the patches to draw themselves and set up a few variables# O( I, H; Y' R: p4 z
  setup-patches
! c3 X: K: E8 S7 S. e9 z/ `7 X  make-current one-of intersections
4 y! M6 j6 X9 V' c  u  n  label-current0 d" h8 x" e8 P& {( R
# S# Z6 A5 B7 F% U$ t( ], b; s' b
  set-default-shape turtles "car"
' b, u$ E1 K4 v6 @# S8 Q4 }$ `" z' x! c. l6 \1 B
  if (num-cars > count roads)( \/ i7 ~- r1 F: s# V
  [# N) C$ @4 k8 f. a1 S. e
    user-message (word "There are too many cars for the amount of "5 c9 K" D1 w3 R, N: H! o; j0 A# Y
                       "road.  Either increase the amount of roads "
6 `7 x* `& {% ^* q& f                       "by increasing the GRID-SIZE-X or "( n0 A/ y! _! y8 r: G- Y
                       "GRID-SIZE-Y sliders, or decrease the "
4 a/ i% T$ p7 G& Y                       "number of cars by lowering the NUMBER slider.\n"
) P! }8 {9 k! i& i) b: {                       "The setup has stopped.")' b1 L* u, `% d* i! z
    stop+ M- s$ n# m: [
  ]; }5 J1 m( \; U) T# N* G

6 {6 c- }9 ~' l9 k  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
- X7 r7 D, R) Q: C2 J9 ~/ Q  crt num-cars
" y+ L, u4 \0 J0 U4 c  [
: O# x& M# ~: R5 `) T4 R, {* Z2 P    setup-cars9 H9 ?6 {% w' D1 B
    set-car-color) v$ u0 V7 Y9 t5 e8 S
    record-data8 y+ ~& \; N# Q4 Y
  ]
7 V9 X. x0 p: x' \( @) y3 z7 n7 t
" E' c7 X% E9 x& u) T% K  l( A  r  ;; give the turtles an initial speed* ]1 s* x; M" s1 o2 U
  ask turtles [ set-car-speed ]
3 S! W- H, G6 M* n
0 x3 p* K/ f& q2 Y( p' a, T  reset-ticks
* ~4 H  y2 |! O, j' Uend$ s1 A$ m2 P$ v0 E
+ p+ y6 d3 i7 y% Y2 H' ~1 R/ V# m
;; Initialize the global variables to appropriate values
0 J8 m+ R+ Y9 d: v6 tto setup-globals2 w2 G' p4 D8 f3 i3 L
  set current-light nobody ;; just for now, since there are no lights yet
- e: T; A( p; g& t5 o, ^8 `4 \  set phase 0
, Z' \6 p6 v  \% p! b  set num-cars-stopped 0
7 d, H( o2 E# n2 |2 s2 o* y  set grid-x-inc world-width / grid-size-x
; z( U' _0 a$ C- ]5 H  set grid-y-inc world-height / grid-size-y
5 m, i) C' s% M2 g
5 r) d5 J; @' y& d8 n+ @7 ]7 h  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary2 B% \( [* Z+ `( N& ^
  set acceleration 0.099
( q8 y3 C0 l% n6 fend
" A/ T" M0 \9 y$ r+ w. N9 N- s) I( S4 q: x7 p! S! W9 |/ l- G1 J3 X
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,6 V( K2 E- i/ d- H7 I
;; and initialize the traffic lights to one setting6 w4 |! |# X% T1 H# ^( ?  L
to setup-patches
( X" v9 C/ \: e! e, e  ;; initialize the patch-owned variables and color the patches to a base-color
3 |5 \- o6 I; B  ask patches
; ~( h+ Z5 f( d7 e; i9 @7 W- u  [
9 A+ b( X( G3 h  Z$ U7 ?# G7 z    set intersection? false% B& n- a/ _2 C' D8 Y# t9 z
    set auto? false  `% K! ^1 o7 b( s
    set green-light-up? true7 u2 ^$ _5 D+ n& A! b0 b
    set my-row -1
1 g+ v6 O: h8 Y) S: @, Z    set my-column -1
6 N4 F0 e) ?+ Z$ o    set my-phase -1  T- j  w* i8 N' i+ ]2 ]
    set pcolor brown + 34 {0 l. |, }1 E5 X3 E- G
  ]
6 I6 }5 G, E  j2 X4 `- V
  Z) Y: h4 v  O  l! c$ w( y: q  ;; initialize the global variables that hold patch agentsets
5 U$ s3 p) z1 L7 U& o3 s, `; e  set roads patches with
" J6 y) C3 r$ e0 V    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
* r1 }9 d* W9 t. h  u; D    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
3 T+ k, k# h; v" z; c  [3 z  set intersections roads with
% I# X3 \: J* ?8 K) }# ^5 [    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and% e/ Y0 L7 h3 z+ g- K' S' G  l' B
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]9 w) W  n* ?5 W6 }: G1 j

; Q3 }- Y. g5 ~8 g/ z  ask roads [ set pcolor white ]
3 ]: i5 g/ S( @4 {    setup-intersections( U7 U  n& s3 l4 p/ ]4 q7 c
end  z/ j+ _" k& @+ v8 U1 G
其中定义道路的句子,如下所示,是什么意思啊?
6 K; s% T7 m" I) L0 a- x; q set roads patches with
0 ?1 ~) N. l3 `% W+ e5 C: ^    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
4 s% A. f" g/ m% ?. m; V    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]( u3 U$ A' O) U) D& A  g; i1 j
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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