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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。9 N2 n) ~' @- s5 t
netlogo自带的social science--traffic grid这一例子当中,
) @. x9 A* E! V; `7 Tglobals
$ P: ~3 h- F' ~3 |[
& {  E% R6 z! w- m  grid-x-inc               ;; the amount of patches in between two roads in the x direction% X& r* b6 o7 c, E6 Z1 L# i( z( E
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
9 g) y- B  `- w) e; U  acceleration             ;; the constant that controls how much a car speeds up or slows down by if: M, z* v/ k3 R& C' [
                           ;; it is to accelerate or decelerate
1 [- e  }+ w1 {0 p7 e! Z; X7 r; g! N  phase                    ;; keeps track of the phase- t( b" J1 m/ x9 X5 A5 C8 u& [
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
8 h4 ~  @) u7 f$ K  current-light            ;; the currently selected light
4 f; a* L" z8 j. ?& c. O# a. [" ~  W: B; {) M# E( O8 ]
  ;; patch agentsets
/ [6 d; i. U4 w! r. \  intersections ;; agentset containing the patches that are intersections* t: c+ I5 ?# }# ^
  roads         ;; agentset containing the patches that are roads
8 Z% a+ ]( n8 q- W& F! y' y( Z" [6 J]
0 b8 M3 j4 E6 p  a. R, d5 v+ C! Q$ K3 j& v' R$ a
turtles-own
& a1 N0 ?: Z0 c& Z2 Y" o[- s2 M1 C8 V* ^) P8 X8 q# ~
  speed     ;; the speed of the turtle& z8 S% q; M" e
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
  j  O3 q; N/ z. ?  wait-time ;; the amount of time since the last time a turtle has moved
: E% V! h9 q' @) f]0 p$ F" ?* F- b0 C2 j! P; C% m5 y/ d& F
" X" q9 {1 d1 W6 H3 L1 C# @
patches-own
) p2 {  G0 H, u[* F- ~4 r6 v3 U2 c1 r  t1 o) M
  intersection?   ;; true if the patch is at the intersection of two roads  _+ ~' f4 s; Y  g; G1 \
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
% k. M9 F4 Y0 k4 }                  ;; false for a non-intersection patches.
7 i0 @# p& q- [* ]4 q, C, [  my-row          ;; the row of the intersection counting from the upper left corner of the
4 F2 i2 F+ E" r0 r. m                  ;; world.  -1 for non-intersection patches.
1 B" B0 i+ X. Q8 V$ Q: F& k  my-column       ;; the column of the intersection counting from the upper left corner of the
! r3 r7 w( \( ?  B                  ;; world.  -1 for non-intersection patches.
8 d+ \4 J; s" e  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.+ z, Y$ T& H* F0 W* t; E. u
  auto?           ;; whether or not this intersection will switch automatically.: R6 B8 q' n# a; n  E! N9 f; a2 ^9 H
                  ;; false for non-intersection patches.
7 L: h' r7 ^/ X]  |0 |! s) }% n7 K. B' j

. a2 q# H; B7 x; |: i3 m9 E' k) w* t$ u5 b. z9 q0 ]* J
;;;;;;;;;;;;;;;;;;;;;;) A. G, K& S- M: c% `( D
;; Setup Procedures ;;
# h7 O3 G2 p& B8 Q;;;;;;;;;;;;;;;;;;;;;;
) G/ q" B  F, W) r; k) I( B$ ?) J) E* W
;; Initialize the display by giving the global and patch variables initial values.: S5 `6 {/ P  D6 D
;; Create num-cars of turtles if there are enough road patches for one turtle to* N% u# ]" k/ \+ h; A8 y
;; be created per road patch. Set up the plots.
" b: X3 b/ x1 |9 k6 s+ rto setup
5 p. H+ p# r8 e. i  ca7 I  `$ x* _% j2 q# W2 l
  setup-globals+ j: C3 k' ?. {4 ~

; ~) d# L8 }9 `4 |/ t. A7 p) ?' p  ;; First we ask the patches to draw themselves and set up a few variables
5 z: P6 k: x; P: [* G1 E- d8 V  setup-patches
$ W+ H- P$ g7 O1 o9 U- y  make-current one-of intersections
# w7 c6 `; w* d0 t( Y  label-current
8 \4 W" W7 A/ P' b# ?0 p: ?8 d$ ~5 H4 ~$ f3 Y* Z' o
  set-default-shape turtles "car"4 l" U# Q0 J, Y- f3 X

; r- t: u; \  U. P- n8 m  if (num-cars > count roads)
6 f- @) _3 c, H. u$ d; e  [
3 j+ t1 i" ^4 s9 G# H    user-message (word "There are too many cars for the amount of "+ d# m4 v; N  ~
                       "road.  Either increase the amount of roads "
$ }0 S$ {7 ]# j& H                       "by increasing the GRID-SIZE-X or "4 }/ x( i, S* C! |- I. b
                       "GRID-SIZE-Y sliders, or decrease the "; a: J  K/ e: C/ ?) C! Y
                       "number of cars by lowering the NUMBER slider.\n"& c: X* l5 ^2 V- ^/ q8 ]6 D
                       "The setup has stopped.")1 p) \* W# Y2 [7 y
    stop+ n7 n" ]7 ]' L4 h. q
  ]4 {4 I) C( \& R

+ s7 y* j. o: p7 y7 e- h4 x* D  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
& C. Z0 k  w* ?8 S! }  crt num-cars
4 X; t* \& F; M5 k  [1 {$ A, p, l$ H) W
    setup-cars2 G; l/ ~% z- t2 [& q
    set-car-color
/ F* R# {* `2 {5 b$ [    record-data1 y* p2 _& O/ `& \4 Z
  ]& g4 m, D1 Q' C; r+ Q9 f" q, E' Z
; B2 J2 ^$ j" o# ^; \, L2 q! q1 e
  ;; give the turtles an initial speed
: Y7 k) t  E& U: [" o  ask turtles [ set-car-speed ]
" y+ |9 M* {* b6 w7 @) P* J( A+ f
  reset-ticks
) s& }. b0 c6 _$ r0 M7 Eend" F% v. R3 }5 M0 ]

7 w6 J( x/ J! [0 n, m- R;; Initialize the global variables to appropriate values
  S/ v4 d: H) f# I  o: ?to setup-globals; d- T0 h0 r% M2 }
  set current-light nobody ;; just for now, since there are no lights yet
' N$ q6 a0 `+ ~# [9 E  set phase 0
, P/ o' {0 B* K+ E# ^  set num-cars-stopped 0% V9 N, R  |# w: M; w
  set grid-x-inc world-width / grid-size-x
+ e) `- f* u/ S  V& Q  set grid-y-inc world-height / grid-size-y+ `* L! |1 s* y

' p& |, f4 J, o  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
% o! x2 k  s7 l  set acceleration 0.099/ L$ o( W- a6 k1 c$ N* L9 a
end
1 C5 J3 n( U: K* ~$ \
; R" v! t- e0 ^- B) x  c;; Make the patches have appropriate colors, set up the roads and intersections agentsets,* u+ E/ i& |' i2 p  c2 P
;; and initialize the traffic lights to one setting9 {/ k" N4 {6 W0 K# _
to setup-patches
6 a- O  ~% ^0 C. L) E4 t  ;; initialize the patch-owned variables and color the patches to a base-color
. n9 r( V5 @# b+ F; w0 B! Q9 I& m  ask patches  S$ H2 N$ ]: D+ v9 G2 H
  [. t: ^6 S% {5 j: l
    set intersection? false
- K+ w/ ^. k4 t/ `3 z, z    set auto? false0 {; s( a( x: Z
    set green-light-up? true
& q4 @  @1 D4 \9 f8 `# {; a# K    set my-row -1  G% g% p0 \/ o) O
    set my-column -1
" @4 q; @6 P4 @/ S% o7 g    set my-phase -1
0 _1 x# f6 E% Q' ]9 S, ~6 v    set pcolor brown + 3
, z' x/ e% B. V5 [, h4 J  ]! J& L  k% N# Q" S( v1 Q3 Y" U% }! h
: X1 n/ n0 W  X" v
  ;; initialize the global variables that hold patch agentsets
. o, N, ]9 ?- u# g; E& b* j% e" |  set roads patches with
; \) o/ T; k* `  i  _0 V: m3 b    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or2 u. Q2 j0 f3 V4 C* g" \
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
% C/ F# a2 p7 v. h" l! [  set intersections roads with
) y7 I4 P2 D( k8 I2 y6 O) W$ e    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
( i/ a" E3 |( A$ ]* y8 E    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]% l! ?5 v! q0 x8 s/ i% W! B

/ x6 n! \6 x! V+ G& K2 ^  ask roads [ set pcolor white ]& n, G8 T- H! ~. X) l
    setup-intersections1 k4 m, z9 W  u+ U
end
3 `; f; j; {8 Z, |, F其中定义道路的句子,如下所示,是什么意思啊?
6 u7 q2 T! B! k# r6 W! j  C set roads patches with
. S( J$ t" \  B- d    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
+ c1 s* u, X! b$ `( R( }4 o1 m% v$ h    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]0 v# w* C+ K4 n/ k. [# H
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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