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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。
2 p/ ^  x  g1 r+ A$ M7 G% P8 {netlogo自带的social science--traffic grid这一例子当中,
' f6 ~& F! e% c6 g" tglobals) U7 {1 ~. I0 V7 j# L
[
* k7 N& Q! a) y, L  grid-x-inc               ;; the amount of patches in between two roads in the x direction
9 ^' l% m3 o# l8 O  grid-y-inc               ;; the amount of patches in between two roads in the y direction
+ @5 m6 q  u0 h9 h( ?  acceleration             ;; the constant that controls how much a car speeds up or slows down by if/ C/ ~# S. E4 }5 X# Y9 W! Q) n
                           ;; it is to accelerate or decelerate
& }1 y. f/ J4 T' {  phase                    ;; keeps track of the phase
; e# C" k! ]1 E+ H( U/ r% n0 i. N  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure2 G0 e4 U6 J% @# Q* j5 |
  current-light            ;; the currently selected light
: B  K# {) m' F" s; T: i! t* ~0 q2 T6 O- d2 ~$ q  N; S0 x& {+ u  V
  ;; patch agentsets
$ |/ A# i* k8 A( w  intersections ;; agentset containing the patches that are intersections) h, q7 X% A$ x' |7 ^
  roads         ;; agentset containing the patches that are roads
3 R& b4 U: `$ w( v; }/ h6 K1 g]. Y' }# R# N% e6 V) z2 P

( V! a$ T) R" \% z; Pturtles-own
, ?; e% Y: [) A3 {* W1 p[# U* j7 P1 m; D( {4 }4 f
  speed     ;; the speed of the turtle
6 ?1 c. _7 r1 U5 f4 Q0 i- i  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
* f, ?* d6 b' M' n  K  wait-time ;; the amount of time since the last time a turtle has moved
- E* j8 p4 K  w! g" o& W  k1 \]- a7 `5 b! W" i
/ q2 E$ J0 F0 R6 A5 A- o& L/ f
patches-own
  }" f5 j7 ]' T0 n& p- N[
/ x, g! I4 L- R  intersection?   ;; true if the patch is at the intersection of two roads1 C- ?: O3 _, ~6 k
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
. s  }) ]3 c: \& q                  ;; false for a non-intersection patches.
0 M* ~, w' E& @* w7 O  my-row          ;; the row of the intersection counting from the upper left corner of the
! f; {4 k- G% E, E; M8 n" y6 E                  ;; world.  -1 for non-intersection patches.4 r: |2 t' c, A- s8 `  Y2 v
  my-column       ;; the column of the intersection counting from the upper left corner of the
  F/ ]' C3 N3 A5 Q0 L' [( }2 D                  ;; world.  -1 for non-intersection patches.
1 f! s- c, G: y7 H* G6 f8 M1 }  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
8 L" n, F5 R- R' C5 V: F- C# r: a! t  auto?           ;; whether or not this intersection will switch automatically.* Y7 z4 B- s; f, B* o6 D! w2 D! I  O
                  ;; false for non-intersection patches." j2 X' H$ D& j# ?; t
]
7 Q* ]9 w  U( r  a5 P" M; J0 T: X3 d8 m: {/ Y' r& c) J
5 L% j9 K6 Y$ r- p6 D  o5 _! S
;;;;;;;;;;;;;;;;;;;;;;- N5 G7 v' n/ s/ _6 U
;; Setup Procedures ;;$ F& |# ~! K" U# ~( v$ C% {
;;;;;;;;;;;;;;;;;;;;;;
4 e7 m4 }; k7 d+ S. O$ z
  Q3 S* k9 X. n' d4 r;; Initialize the display by giving the global and patch variables initial values.
% k; H6 {, f' M2 ], f/ x" R;; Create num-cars of turtles if there are enough road patches for one turtle to
" l( T1 k- `# F( g1 _2 J;; be created per road patch. Set up the plots.
  n5 |3 p0 ^% F" z2 jto setup9 z- }; J3 X! z
  ca3 }9 ^, ~0 V% z- b. W8 q2 @
  setup-globals* D, l$ e/ @' |  Y% d, q* T
9 x0 p. c6 V- e. P7 @
  ;; First we ask the patches to draw themselves and set up a few variables5 Z- C* k% ?! p1 t* Q* u1 I
  setup-patches2 C0 ]/ w# D- r" G
  make-current one-of intersections# e5 ~0 D9 i- h3 R% x
  label-current$ y2 W5 |# V) \6 Q* W

$ M3 {9 l* ?; S  set-default-shape turtles "car"% j7 o$ A& {! }- F. d( L
+ l% U2 `2 f# ]* i( ?7 x
  if (num-cars > count roads)
2 Y6 F! R% F1 {1 e8 {9 s; k  [% b. Q" s- @" i. h6 T) D4 W
    user-message (word "There are too many cars for the amount of "
  u4 l9 }# _: z+ R                       "road.  Either increase the amount of roads "
! H1 g( b* X+ H( Q7 T: n- g$ E                       "by increasing the GRID-SIZE-X or "6 n% ], k- Z& [# |
                       "GRID-SIZE-Y sliders, or decrease the "
: T& q' L% d6 W: {- q                       "number of cars by lowering the NUMBER slider.\n"6 |* A. s/ h! _+ m& m
                       "The setup has stopped.")9 ~" W; p7 }. A# y! I! F
    stop
: M  F) ^) L* h, s  ]
$ V+ c7 }2 P/ p, k, I2 P. i9 U( W( A! I
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color/ p0 _/ [6 Z, @) T& C* ?( @5 B
  crt num-cars
) y) L7 H8 o5 s9 w4 z  [  v: V, ?) G" y' D+ {
    setup-cars
! P  e5 w7 p, S% _& j( }0 k    set-car-color2 D+ G. E7 }( M# u1 C  ^  u: i
    record-data6 @) T! g" B& v( C, X
  ]
6 x5 u( X0 Z5 d/ U" \4 Y! n* a- Q" c: w6 t
  ;; give the turtles an initial speed+ ~- E5 C, j& n  X; k
  ask turtles [ set-car-speed ]% W& @7 j6 l/ N. ^

- Z. s# N3 r6 K% a; ]  reset-ticks
1 ]; N7 |% V1 {0 B$ fend  V4 f6 |. a: X4 l( {- B. p

3 Q/ c6 c9 b. F0 ~- E  @: u;; Initialize the global variables to appropriate values
- q" T% ?2 a  P4 @to setup-globals
' X- z) F* [5 B6 y  set current-light nobody ;; just for now, since there are no lights yet! i4 A( T5 S, I/ H$ H6 Y+ S3 p
  set phase 0
  o8 Q4 ?- J1 e! c- o, ~) H  set num-cars-stopped 0. ]0 S4 e: K4 ?3 j' u  v) a
  set grid-x-inc world-width / grid-size-x" C" Z* t4 L) q0 E
  set grid-y-inc world-height / grid-size-y- l0 V& s# z% D; b/ }! }

6 C; P7 J" Q8 J0 X) {  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
- t( w, k( }8 C! H1 N  set acceleration 0.099
; H2 c, [3 @1 t/ r! qend; y1 O* W  W# H" `
* f; E5 }/ X- P/ I
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
- K" s8 g/ `7 G, s$ k;; and initialize the traffic lights to one setting
% b9 |+ T9 C* n/ Yto setup-patches
4 @- l* @0 p9 r  ;; initialize the patch-owned variables and color the patches to a base-color% i) c3 \" E4 x8 j2 W7 _* z
  ask patches
; R  d1 d! i# K: }- }  [* ?1 T9 C4 c( l# ?
    set intersection? false+ c1 w6 A1 |" y9 j) Y
    set auto? false4 N; D( C7 `# L# E9 f9 Y2 y
    set green-light-up? true
0 ]% j- P$ O* Q9 w    set my-row -17 A3 _, {4 ]4 r7 j8 g  m" Y
    set my-column -1
: E# M! ?; l* F$ T# {+ b) H    set my-phase -1
9 N( X9 u3 \, T* N3 T    set pcolor brown + 3- @# G7 }6 ?' q; o+ i6 `
  ]
7 F7 C: q2 v- Z7 l  D  ]6 _0 w# W! ~1 D/ H3 K7 B1 L  k
  ;; initialize the global variables that hold patch agentsets/ `; ]# f; P' Q" w+ B& O
  set roads patches with5 e0 J0 i2 b1 n: h4 P
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
% r- s: i! z. F5 ?    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
0 |0 k3 ^- p' ]: Z  set intersections roads with
( r5 ^: H- d/ E' f$ p, o    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and' C1 m' z( t8 }2 m' R+ g
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]6 a5 E3 z$ ^  n1 f; D0 q
- C) c6 j% i) J* _* s
  ask roads [ set pcolor white ]0 Z+ O$ C/ [# N% ]% C' ^; n* b# B: k
    setup-intersections
: B. ]+ K7 Z4 Fend  N1 p8 q' \6 F, x
其中定义道路的句子,如下所示,是什么意思啊?* e5 m4 {/ g& N
set roads patches with
$ Q; ~2 Y. x  W& T  I! `- L3 a- s9 M    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or+ I2 J/ I; k) H) X& v. e
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
9 T$ b7 a- |0 ?  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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