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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。
5 S; `: C& i1 e1 ?netlogo自带的social science--traffic grid这一例子当中,/ I+ G5 y' s5 |4 [2 Z1 n3 [& D& R
globals$ S4 S& O6 H' ]$ T. \4 h2 \
[
9 ?, Z" A/ M. Y0 e4 t; A+ A  grid-x-inc               ;; the amount of patches in between two roads in the x direction2 F1 u! B5 Q& M7 m
  grid-y-inc               ;; the amount of patches in between two roads in the y direction$ B1 M4 U2 Y4 C% z3 e1 B4 g& G5 M
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
: [6 F7 Z, j; ]                           ;; it is to accelerate or decelerate
; T% S7 @, e) f8 y( A  phase                    ;; keeps track of the phase' O( ^8 q4 {8 o* M  K& ~& U" p
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure, z! J8 \8 R5 y3 [; w
  current-light            ;; the currently selected light
* Y. ^3 ]/ U- j# Q7 N8 L
7 m2 M: b! H0 M( X; n) W6 m  ;; patch agentsets
. |. S$ X3 o. o, H  k1 z: x: i  intersections ;; agentset containing the patches that are intersections& C3 F4 v; P( d# g2 U& d6 N: [
  roads         ;; agentset containing the patches that are roads' M  `1 f' e- T; C" m
]
) }3 l4 H) M5 s% r; I; o" W( U$ z9 s- E
turtles-own
5 K' Q1 Q8 o  ]2 n% `3 @[
* y* _7 g. Z* `  speed     ;; the speed of the turtle- S* }4 K$ T/ F+ e+ X8 D! ?' f
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right' w* x; c. n( R" X, b- T7 w
  wait-time ;; the amount of time since the last time a turtle has moved6 C4 k- S$ G7 r7 k" x' @4 {6 N, U
]
$ s* a* q4 U% Q3 V% S( K3 J7 ]- f9 c( P8 m6 g2 u
patches-own( Y8 @1 C& n* a) q! w( R
[
/ k% _  S6 J8 K- ]& M  intersection?   ;; true if the patch is at the intersection of two roads
( L$ k7 K' U9 X# ]9 n7 R  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
8 H6 Q0 ~! j  i$ ~                  ;; false for a non-intersection patches.$ u& Q  B2 M0 F* {7 c
  my-row          ;; the row of the intersection counting from the upper left corner of the
! U4 d* w+ z; d, {8 s+ A6 H$ ?                  ;; world.  -1 for non-intersection patches.& X; _1 j( i& [% P7 l
  my-column       ;; the column of the intersection counting from the upper left corner of the/ U( d, a' D! ]
                  ;; world.  -1 for non-intersection patches.
, |9 U8 ^" U. U" q( z/ g( Y  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.  ^$ u* X6 @/ o. d
  auto?           ;; whether or not this intersection will switch automatically.
+ F7 h/ v5 Z$ d; \. C  s% d0 x& y                  ;; false for non-intersection patches.
2 G8 y  q, w4 w]
- j1 A9 p" {' Q# ~* P' A4 S! j" c. ~

0 k* X8 E7 `& G: a( F;;;;;;;;;;;;;;;;;;;;;;$ @: [+ v/ T) F9 }1 P
;; Setup Procedures ;;2 R1 C; F% w( `1 L
;;;;;;;;;;;;;;;;;;;;;;" B  u5 ~) e: @* _+ K; E, E; i7 m9 j2 B

6 ]5 ?7 ?( Z# V7 |9 O, ?;; Initialize the display by giving the global and patch variables initial values.
' w" X1 V, C4 P, V" m2 `- N;; Create num-cars of turtles if there are enough road patches for one turtle to
9 o$ }, n5 V8 ~( D2 c" y! ~;; be created per road patch. Set up the plots.7 F  d& E" U# I4 L2 s+ `6 U
to setup
! J- C' k$ J  @9 R: Z1 D  ca- f$ ^: u; R5 s9 J5 _
  setup-globals
: O$ @2 |# b5 ?3 J) j/ C- W  N5 N* k8 s4 }# ~
  ;; First we ask the patches to draw themselves and set up a few variables
  d2 a+ X! x$ I7 Y6 \! {- D  setup-patches" c; [: ]! O2 l' h2 f5 D- _6 P
  make-current one-of intersections
( e. a. B9 A% `- k3 Q  label-current; Z3 `5 _$ O& @, V2 A+ X' h  L

- Y* m4 U( v2 J  set-default-shape turtles "car"
4 t' y' _" M4 P* `: `
# K5 Z8 e$ w) I2 k& |& F3 H7 b  if (num-cars > count roads)  M- O0 A' m% k
  [$ V' y% Y2 e  z: t5 p
    user-message (word "There are too many cars for the amount of "
! j1 `8 I9 b* `* ]; c" W$ T+ r( L                       "road.  Either increase the amount of roads "
! B5 @0 Q/ Z) F! \  t                       "by increasing the GRID-SIZE-X or ") O2 q2 h; l  I( M2 o
                       "GRID-SIZE-Y sliders, or decrease the "
" q* E; L2 _% }* l" {                       "number of cars by lowering the NUMBER slider.\n"
- u( ]1 v  |- f  [* x                       "The setup has stopped.")! Y  Y- w4 o0 ?+ ?) H* w8 n3 h  a
    stop
, c: }# ?. W* Q6 X( W1 \  ]) ?3 h( x* E- q' }) w
  r; `# e: y- x, s
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
& E$ Z# A6 j4 O( d  crt num-cars
- w! q% Q! I& _  [
; L8 v6 R$ M! H7 P4 a    setup-cars+ W5 z1 G# d. V. {2 V6 b% Y) t5 L; K
    set-car-color+ H% @+ f7 {) w8 R2 E$ l% q
    record-data
: f4 N6 D) g$ o! ]. _0 R' J1 J( g- g  ]
' w; I  F- t2 w+ a/ _5 S! j. D$ u6 K2 N/ }; [+ ^% S7 ^9 D! q$ D
  ;; give the turtles an initial speed& k  q% e5 t/ r5 p
  ask turtles [ set-car-speed ]
4 _7 f1 N: J6 |. v; A( Q- y" q, }; N" l  r
  reset-ticks7 \* P3 u/ ^7 O4 @3 X& t! l
end
7 c$ g& K8 v1 d. g. ^
$ `) ]8 P" @9 j. u# c( n6 `;; Initialize the global variables to appropriate values+ k# ?5 E0 l* E  r/ E# q
to setup-globals# Q: z* Y8 t: Y' P1 x0 d" E" u+ N( a
  set current-light nobody ;; just for now, since there are no lights yet  W$ |) y; u% C; r6 m0 R$ t
  set phase 0
: c  o( O! W) X' I5 ~1 ]4 g  set num-cars-stopped 08 ~. n# v  |1 K/ g
  set grid-x-inc world-width / grid-size-x
0 W, }! `4 b2 L  set grid-y-inc world-height / grid-size-y
8 }) s8 w3 ?3 [4 b' A! p8 i
) e, q! o5 \5 v  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary/ F* k1 i6 e1 v& V3 n1 Q
  set acceleration 0.099% {0 K5 v) q* N9 `$ ~& ?
end
( m5 ^: w* I3 n/ U% N3 o" b9 K
- U, K! S( |3 p) d# ~. @8 c;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
4 Y+ l  G9 K" ?;; and initialize the traffic lights to one setting+ f9 K. K: }$ p3 P0 y
to setup-patches
- V* g! b1 |6 c5 m8 n; p" x  ;; initialize the patch-owned variables and color the patches to a base-color
0 j% ]; p6 S0 I/ E  d  ask patches7 q5 [" q, Q# y( i5 `& S; p+ y1 t3 s
  [
$ N2 x6 n% o9 _/ a    set intersection? false/ n! L3 C! [% u5 \9 y2 b$ r
    set auto? false
$ Y  u" B: j7 i  }/ ^% |8 y    set green-light-up? true3 ]7 g9 j; g- ?$ E8 R7 N- L6 ~& `/ e
    set my-row -1
3 S4 {6 a8 p8 S6 a0 G% N    set my-column -1
' u% C( S5 t2 y; o. U    set my-phase -1+ |9 G3 ~  v9 |, ^* w( L# t
    set pcolor brown + 3. U2 a; }# `6 u- f; e: K% f: m
  ]8 i- \% o7 {5 x

% ?7 M6 B# I8 }0 C  ;; initialize the global variables that hold patch agentsets6 m: x6 D, R- ]; [5 L9 E! o0 R
  set roads patches with
2 Z2 }4 S/ r/ |8 z5 P2 _5 \    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
7 W" e' o: M3 m. B8 U  l  f6 j    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]( m1 E* v  z! o! K
  set intersections roads with3 K) c8 n$ H# i: H/ H) B
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
" j% A! K/ ]- v4 s    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
& D4 _* w! w! L  ]3 _
# `7 q0 k- E! x* F  ask roads [ set pcolor white ]
9 W7 }& S5 M+ C8 e" H6 G    setup-intersections! I$ [+ _# }1 k* x' E
end
. Q1 j$ l0 R* ^其中定义道路的句子,如下所示,是什么意思啊?. @( ~1 g) D) h, t: ?4 ?, z
set roads patches with
, X$ ?" K/ q2 Q* o* O3 s+ V    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
6 V4 q9 B* n4 v2 ]% P( l$ W    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
" Q$ z7 l9 O/ K, M: H9 k8 v# Q6 U8 P) I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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