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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- [8 r7 A8 N4 O  lnetlogo自带的social science--traffic grid这一例子当中,2 j: o& N$ s/ u7 ~* z
globals
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. A( K: c/ M) S+ r) L1 _  grid-x-inc               ;; the amount of patches in between two roads in the x direction( P1 n' Q. T9 R1 `/ H' {& x! |
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
: ?3 |9 H2 Y8 t: C  d6 N6 y' C  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
6 p& @/ g' k4 X$ O                           ;; it is to accelerate or decelerate# P5 B" n; |# V' j% A7 M* d
  phase                    ;; keeps track of the phase
4 {; L2 [# f7 U* m6 `# Q  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure! d4 V6 E0 K6 l
  current-light            ;; the currently selected light
6 E! ^7 ]0 p& a( T! ?# ~. `! d9 N0 t) b- o1 R
  ;; patch agentsets3 \2 a! C/ a4 M1 O) |9 k
  intersections ;; agentset containing the patches that are intersections+ {8 {7 Q, U) _8 C2 P. Q$ x
  roads         ;; agentset containing the patches that are roads
  B; F. _3 v/ A4 m]
9 @3 I2 a$ R& D, X! }2 E2 B  g; ]0 m
turtles-own
' ]+ c$ }5 v( V: F6 F2 e! A[; [4 k; @+ L- l6 d
  speed     ;; the speed of the turtle
( s; c% c" y3 `/ j8 e; b$ e0 M5 ?  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
" b/ Q  a* S/ b5 B  wait-time ;; the amount of time since the last time a turtle has moved  M( S$ y7 W3 I$ J, Z- k7 t
]( B  @/ R& q5 u* |6 g. X& h: A1 e
9 Z' N( S' M6 H4 i% }  n, B0 H2 ~: J
patches-own0 F; x7 q! s- ~( ^' Z. n- Z
[" U0 k- _2 T5 u; v
  intersection?   ;; true if the patch is at the intersection of two roads
& b: L3 |: Y1 k$ u  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.0 l3 d7 ^# M' P& X5 F' j* n( D
                  ;; false for a non-intersection patches.
+ q3 e: Q0 c- @$ G: L  my-row          ;; the row of the intersection counting from the upper left corner of the3 m# i# Z/ `3 i/ o9 g! s/ P
                  ;; world.  -1 for non-intersection patches.
" Z! {4 |' C6 i0 E# N3 |  my-column       ;; the column of the intersection counting from the upper left corner of the2 F: ?+ u8 m$ v7 y  ], l8 j- p
                  ;; world.  -1 for non-intersection patches.' P* Q* j( o$ K* E7 z5 l
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
7 @3 ~4 N; `$ m; v2 S0 k8 Z% g  auto?           ;; whether or not this intersection will switch automatically./ n# U+ m0 y% R5 k6 n
                  ;; false for non-intersection patches.# C: a, o7 A+ h8 m! x! r
]
3 X  O1 v' F' l) b4 c$ S
* W/ i/ \0 o) d2 L' m% g! h0 O+ ]$ ?! G# {! I
;;;;;;;;;;;;;;;;;;;;;;: i$ p& m7 g" X. c- r& [6 X
;; Setup Procedures ;;$ S  W4 v! p% X5 B) J. B( ~. I/ Z
;;;;;;;;;;;;;;;;;;;;;;( u' h  [# E* J

: h0 m* J  e9 r9 r2 }" C;; Initialize the display by giving the global and patch variables initial values.
9 j) ^- q! z1 t;; Create num-cars of turtles if there are enough road patches for one turtle to, h# Q/ R5 r! j6 o
;; be created per road patch. Set up the plots.
8 i  @1 K& l, Q9 S4 ato setup
" u, N: n! R# T9 L  q% w' F  ca  S- V+ o; u" r
  setup-globals
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  ;; First we ask the patches to draw themselves and set up a few variables& W8 p, C0 t" i, v. [
  setup-patches
; i7 y  v! B2 S9 T  make-current one-of intersections; w* d8 m- R$ [! e% D
  label-current
/ c7 m0 b8 H" v1 H0 x. c, U' I! M8 F8 q8 E! Y2 ?5 B& ]
  set-default-shape turtles "car"
' |' X! F7 C) b; O/ {' f& u* r+ s9 K% ^/ x8 w1 t1 g" }2 K
  if (num-cars > count roads)/ R  c! N' a8 N
  [: X. L4 V1 o4 D6 r& `6 Q% ]
    user-message (word "There are too many cars for the amount of "
' k! A7 |8 E4 ?/ t) c                       "road.  Either increase the amount of roads "( ]1 L" g& Q' c  F' [7 R7 u, Q  X
                       "by increasing the GRID-SIZE-X or ": i9 E; _+ d" R8 \/ G, \
                       "GRID-SIZE-Y sliders, or decrease the "
- a0 T% d: v( q1 W  s/ F3 q, N1 O2 i                       "number of cars by lowering the NUMBER slider.\n"& n, j, J' P" R# [
                       "The setup has stopped.")5 t) a+ M6 A3 R
    stop
* S% }  p) n+ s& x  ]
% m' C  Z3 U9 R* o3 |9 |# P0 p! R3 E5 m! H5 w6 u2 L; W7 p
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
$ U% ]2 ?+ i) T  crt num-cars
) k, Q. E9 K- B; [  [3 K' R& X/ C8 T! p' {9 W
    setup-cars# T8 j7 G/ j4 p" ?( T9 }; \" M: c
    set-car-color: n) `) k! D4 }* `  z. J
    record-data0 }+ }, u9 A! d# U5 ]  P: T# J3 \
  ]
8 T% q. z: E  l& y/ {
0 I) ]' h7 K8 r  ;; give the turtles an initial speed2 U! |3 B( S/ ]
  ask turtles [ set-car-speed ]
8 {7 ~5 l* \) y4 ^1 C# k) {- X5 u9 c/ y: ?
  reset-ticks
% U0 b! {7 q% S4 Z) D& {end+ j  {/ ]9 d0 g; |1 ?5 _6 s0 d# v

0 c7 `3 X5 o) p! L;; Initialize the global variables to appropriate values7 ?" v5 l% k. K6 p7 x( i& e, t# P. Y1 o
to setup-globals
( F" G" Z3 o" _0 @  set current-light nobody ;; just for now, since there are no lights yet
& n9 _  o- u, T* R# ?  z7 J3 O  set phase 0& l. B1 B' U. s9 g% @
  set num-cars-stopped 0
; S$ @1 ^. z0 x* R  set grid-x-inc world-width / grid-size-x# R6 \# s( x) K6 R% F+ F
  set grid-y-inc world-height / grid-size-y/ e$ ^, B3 Q( o& t

) }0 E( [; m% W. Z# }  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
! H, |* _$ x7 Z  set acceleration 0.099
$ g: x8 j* i3 Y. W, |) O0 T" Eend
8 |5 Q, K1 {- Q! M( k' }
) h# y& r1 P& J: {;; Make the patches have appropriate colors, set up the roads and intersections agentsets,  r% d$ d( H0 F. ~# U6 `, N
;; and initialize the traffic lights to one setting3 m# k' v' }7 Q) |9 p, P( x9 I# m
to setup-patches$ E, x/ L, [& L* b
  ;; initialize the patch-owned variables and color the patches to a base-color! O; @) L0 t1 l- V
  ask patches9 M9 t- n$ \7 b
  [: s% C% m) s# P1 ^
    set intersection? false
& g& X$ Q" Q+ v: \* f% x5 d    set auto? false% m8 F; I1 B  F9 z+ \5 \+ ]9 x
    set green-light-up? true
( A. E4 z, V- o. k& x! U    set my-row -15 ~+ S3 h7 o! j. r2 T' X9 K0 b* V
    set my-column -12 y' k6 y. J; H; O2 v" P6 r7 x
    set my-phase -1
3 b& Z, Z6 j6 P% |    set pcolor brown + 3+ ?1 ^& n3 b2 \/ V. f4 H. Y
  ]* l6 Q7 N3 e) E! T  J# k6 B/ X1 _1 s
# q" }( v  i6 f/ N5 V! A3 P
  ;; initialize the global variables that hold patch agentsets6 u3 b/ p% z& ?; h( G4 o! {
  set roads patches with
2 e' T: u. D0 f  P    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
0 Z- e' G( t9 |" e    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
* B7 U7 O; ^! z9 O6 `; b4 H" p9 O  set intersections roads with% r  @4 U! l5 A9 B, f7 @* v: n
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and& l( J2 n1 P! J. n5 s# ?! @
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
1 X5 N2 S7 X( O: J8 m1 ~5 w) N* Z0 Q8 R3 P4 U' E6 h  V* u# ^) q  P
  ask roads [ set pcolor white ]
0 D7 e* d, G7 o! `: \    setup-intersections' V5 z4 y4 g* l) F0 F9 y
end2 g) S9 ]. X2 x6 I! U
其中定义道路的句子,如下所示,是什么意思啊?, X5 N. a: B9 K: c) p
set roads patches with
$ V- I1 T$ z% Z2 V$ |8 Q    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
0 y4 b" c8 w2 k, {* k+ d    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
0 O7 b( X# l9 n# g' Q- ~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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