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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。& l" N; A7 [6 J1 e9 p
netlogo自带的social science--traffic grid这一例子当中,
* a6 \) z) {# n. ^! ^globals
  [4 y/ A' x9 X[
' L: v7 D( L. h' \  grid-x-inc               ;; the amount of patches in between two roads in the x direction
( u, ]6 b# c( o: ~0 `  grid-y-inc               ;; the amount of patches in between two roads in the y direction7 `" a" f$ l  [
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
3 T; f+ O  P: J6 K) X                           ;; it is to accelerate or decelerate
4 N- |/ m' L6 _2 K7 a) W6 p/ t  phase                    ;; keeps track of the phase$ s) V# i/ B8 \# P+ k8 A
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure! m$ ]- R: M% t% ]0 U
  current-light            ;; the currently selected light9 E9 u6 w& H- g$ x
  T" q" K: `. k. E- A# N
  ;; patch agentsets
" D- T, E' v* U" T/ a1 {% s  intersections ;; agentset containing the patches that are intersections7 \  b. k" P6 \8 e( V# Z: }
  roads         ;; agentset containing the patches that are roads4 x5 }) Y: h4 c1 F5 \$ W
]: N! c4 X: b: j, C, L9 B
" x/ N: M1 c9 ]/ w  ~, m5 g9 q1 N
turtles-own; W, M+ ~' V9 d: X; N( U2 S( Q
[4 a# V9 p3 r2 V* u, z
  speed     ;; the speed of the turtle/ L. ^3 }' R& O1 d* {
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
: r, r* p* l6 y! v  I: N3 G) [; |  wait-time ;; the amount of time since the last time a turtle has moved
# h' B4 @& e! e7 q( `# k]+ M3 L6 {( j. ]! a0 v' v; ~0 ^- }4 r
7 O  }. \. Z) O" M) {
patches-own
- U4 {1 `2 X: v7 B6 K7 o[
' h9 Y6 @, f7 ]  intersection?   ;; true if the patch is at the intersection of two roads+ N* g6 q. i$ D# _
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.+ E( Z" J5 d- e* ?% t; }
                  ;; false for a non-intersection patches.
; `% l; R9 @1 X/ C7 U, U  my-row          ;; the row of the intersection counting from the upper left corner of the! o- |2 C" A  e3 J# J
                  ;; world.  -1 for non-intersection patches.
; A. j2 O; c! @6 f; j  my-column       ;; the column of the intersection counting from the upper left corner of the
' }& w/ }; J, B3 L# _                  ;; world.  -1 for non-intersection patches.
5 T- r  {' m& ^  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
; c. @) K; @" r/ J& Z* u# B- e/ i  auto?           ;; whether or not this intersection will switch automatically.
+ k+ c6 f' k; E+ i                  ;; false for non-intersection patches.
; _6 p/ Q, f" d( \( b7 `]
' v6 \4 h7 b3 u& c8 s! v0 Z8 z) ]3 _1 u/ y2 D) m  ^
4 c4 s/ f  p) e( T* ]. Z& C
;;;;;;;;;;;;;;;;;;;;;;
- n8 j3 a# ^7 t0 [; A- I) Y6 E;; Setup Procedures ;;
  Z6 z, }$ {; x+ |;;;;;;;;;;;;;;;;;;;;;;
) T, D2 j" C) ?. P& {1 S9 B
7 K- ^6 U$ Z2 ?% t2 u' c0 a# G;; Initialize the display by giving the global and patch variables initial values.
9 I6 q" q7 W7 \3 w9 w;; Create num-cars of turtles if there are enough road patches for one turtle to/ u' r$ }0 R  U1 ?+ n
;; be created per road patch. Set up the plots.
) t. y/ D- N6 }2 ]to setup
' r6 ^% v/ [% m  ca
. K% Q; h( p1 [' F& d  _  setup-globals- B8 r, i: h$ f+ d# A
0 Y+ Q- G  n3 O$ j' i  M+ `
  ;; First we ask the patches to draw themselves and set up a few variables
1 m8 h+ T$ |$ i8 P' q9 r$ ~  U  setup-patches
  R2 ~; ?$ {$ v1 t. p  make-current one-of intersections. j, W7 M5 j$ i
  label-current. x% A) `% R% `

6 j/ H0 F# Z3 k5 G  set-default-shape turtles "car"4 O/ I1 U$ l" M0 N

4 ]% d# B* H( g% t# q" g3 c  if (num-cars > count roads)) X2 x) J' y5 L# s" {& _
  [
7 [/ w: L% y7 E/ G1 o3 O2 s4 y4 E6 g    user-message (word "There are too many cars for the amount of "7 i7 Z9 j2 z/ c2 L, F/ u% k
                       "road.  Either increase the amount of roads "; x& C, O3 w' M( y) p& g
                       "by increasing the GRID-SIZE-X or "
- |6 `/ V1 z) |& x. [$ g1 Q                       "GRID-SIZE-Y sliders, or decrease the "
, ^# k7 X6 t2 [, m                       "number of cars by lowering the NUMBER slider.\n"
6 E* l/ ~( K% D. g4 p- h                       "The setup has stopped.")
9 a0 N8 O- W; @2 i: v    stop4 x2 I  k! B! R1 u
  ]9 b, @/ F! I7 T3 h3 g& _

3 F& P& }: E2 n7 {  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
0 {: y0 T" q# J1 ]0 @( D; Z  crt num-cars
7 @7 ]* y/ k; ?9 v" ]$ Y# `6 t  [
4 `  O6 ~9 J9 X7 v2 C! o0 E, r    setup-cars
0 c- a& q  e5 J0 R. l/ L    set-car-color
& M) h" }3 j# L! j4 P& K1 l7 }3 |    record-data" Q% i- r0 B, Y9 a% f) Y0 \
  ]
0 ~) O4 G: w! v) P: v% Q7 T6 x9 |* x* y1 H+ q: s& ^+ m
  ;; give the turtles an initial speed3 Z1 B- U: m% R3 k5 Y/ h/ ~: i$ h
  ask turtles [ set-car-speed ]
. i# e& d) K  o5 A. v8 K& q0 M" m2 l& q$ j  ]3 C# C
  reset-ticks
- W5 q( A* T6 F' vend8 @8 ?" G5 q% a  |# `0 E7 s
+ S3 @: M2 e1 x6 p
;; Initialize the global variables to appropriate values
- ~' u% c$ Y) ]" M( Y' d1 X" {to setup-globals
2 x5 d( O+ f6 Y5 n$ J' o8 p/ H  set current-light nobody ;; just for now, since there are no lights yet
: }# ~. B. K% R& _; a  z" W  set phase 0
% u3 j6 y' a6 P) Z9 @+ n: M  set num-cars-stopped 0
2 I$ W: J+ d* n2 h  set grid-x-inc world-width / grid-size-x
( a7 [9 w' D) F) H  set grid-y-inc world-height / grid-size-y8 t' G+ Z; \' ]/ k+ N8 E1 v; V

; T: K6 y: O+ x# J1 z  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary4 R. i$ V0 V  p% Y5 q4 {
  set acceleration 0.099; u* T0 l3 p' G$ @- f$ b
end
1 L; H' {, o' O. D- \7 A5 H
) Y+ ^" @) f6 h6 k% s3 C& Q+ A/ K;; Make the patches have appropriate colors, set up the roads and intersections agentsets,5 c! B& _% E# ?
;; and initialize the traffic lights to one setting4 e8 R4 }" a: Z: q; ], p
to setup-patches
0 v, D. d7 N$ \6 i  ;; initialize the patch-owned variables and color the patches to a base-color
1 S% H) T$ d2 f6 R1 S  ask patches; [, j2 W5 d. e$ [1 i; e
  [
5 y) X% W4 U2 m% \' G    set intersection? false
* W8 x  R4 f+ a1 ^9 Z, a/ E  m, [    set auto? false& z) b, o/ r3 D9 @! M
    set green-light-up? true
; B6 N: S2 a. ]" F    set my-row -1* b) y7 Z4 u1 o
    set my-column -1
! o7 f3 V+ n5 n! a) C/ P7 K    set my-phase -1( p- n: ]( j' L' }. u
    set pcolor brown + 3
) I! J1 \! j5 }$ Q: B/ }. `! x( }  ]' b) x+ d0 H0 V, s! Y

" ?8 t  o' r# ]) r  ;; initialize the global variables that hold patch agentsets( d3 [5 n$ z& J/ G3 v+ _
  set roads patches with
6 W/ I; I: f: J" s0 E  z7 w/ A9 L( h3 a    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or4 |& F0 `1 u3 ~8 S) e
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
% T3 S3 X+ t3 p  set intersections roads with- v6 z) b+ g& M; G; ?7 [& G
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
% K* g) O5 N! A3 Z) f) w( a3 Q    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
/ U6 T4 q9 i7 ?+ W5 J2 W6 _, x( \0 O% B4 q) r
  ask roads [ set pcolor white ]
' T3 ]" u! V8 ^- s' n# z    setup-intersections# E, C2 O9 k9 m* f6 d4 L. i
end  m/ K7 X( d7 `4 v+ }
其中定义道路的句子,如下所示,是什么意思啊?2 ~' V* J0 H1 Q" V) F9 y
set roads patches with2 ?0 A; B4 q4 A0 x2 B9 s+ u# Y5 O
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or- w# ~# U& ^+ B; D2 q6 f
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
- m, y# g0 H* V. L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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