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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。4 Q9 S& C' ^2 a7 A( R# i
netlogo自带的social science--traffic grid这一例子当中,6 e1 Y. @( V+ [. m
globals! z" @* d4 C  t; m! S  |
[
' a% S7 w" m6 n8 Z1 V2 ]: r  grid-x-inc               ;; the amount of patches in between two roads in the x direction
* d1 m$ G* Q: O/ p% r$ A  grid-y-inc               ;; the amount of patches in between two roads in the y direction9 {& o! f! s7 o2 H7 }
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
5 O# L% O0 q: H7 w  B                           ;; it is to accelerate or decelerate
$ d8 @9 |$ {% r. h2 h3 S  phase                    ;; keeps track of the phase6 `6 N6 {8 o$ ?" y% i7 E7 h
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
  q4 _9 M+ B1 {! _! `  current-light            ;; the currently selected light
7 [# Y# w3 ~9 T0 B6 Q( y2 r" x
' C, R2 h" w+ ^  ;; patch agentsets
$ `* w: b$ x- B& K. E  intersections ;; agentset containing the patches that are intersections6 n5 m- A  r: b0 ^
  roads         ;; agentset containing the patches that are roads
& u+ C  u. i# e$ e" O7 p]
* ]- s) d  B6 G0 `7 l6 U- J5 n& X" Y$ @' M0 \
turtles-own
4 s$ ^1 l, r) h  P6 A% b2 A[8 k. A& }# b& W0 D" q& ]4 ]
  speed     ;; the speed of the turtle& g. L( {8 a. e- k" N
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
9 v, \: E" m. v! m  wait-time ;; the amount of time since the last time a turtle has moved& H& t/ E3 r9 @0 G1 |. C) G
]
9 |: i: J9 ?2 W; T
' z& _7 W; d3 `# o: dpatches-own4 k7 E! [% S- ?1 \  j0 E) r
[: h8 x" ]( ?' J7 ~$ u4 X- e! ?
  intersection?   ;; true if the patch is at the intersection of two roads$ o. s, [$ w/ o9 n
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.; m* s) ~5 i7 s
                  ;; false for a non-intersection patches., l+ o2 C* P8 t9 F- ?1 Z1 H
  my-row          ;; the row of the intersection counting from the upper left corner of the# R3 v) a: S/ `3 s% l+ [
                  ;; world.  -1 for non-intersection patches.7 N0 ~: d! V+ l6 n! M( W' Z2 o8 G8 `
  my-column       ;; the column of the intersection counting from the upper left corner of the
- c6 T4 `3 y: y. U5 S5 g  O# m$ z" N                  ;; world.  -1 for non-intersection patches.
/ U1 w  L8 D* V" b3 J5 k- J* p  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.' Y8 u% h0 F* E% f2 I8 I" ]' D
  auto?           ;; whether or not this intersection will switch automatically.
5 P2 G/ }7 d# Y' y5 P4 E& m                  ;; false for non-intersection patches.
' i& N' u3 ]! \" D5 b, g]7 y9 S2 k9 W5 Q4 G

" {) @# L- o. l7 n6 Q2 D, x
0 {7 J, V" i: M- `0 E3 `;;;;;;;;;;;;;;;;;;;;;;* m5 X6 v4 o6 j* h( a
;; Setup Procedures ;;
+ R4 R8 x9 O8 t. F5 T6 T: A- W. a3 A;;;;;;;;;;;;;;;;;;;;;;5 B) L) Y, J; ?( V  Z: p

+ O" A' f) r6 U& x;; Initialize the display by giving the global and patch variables initial values.
9 M$ Y8 r# k$ Z. p;; Create num-cars of turtles if there are enough road patches for one turtle to
$ c9 X  i+ p- O: F0 e$ F: H+ j;; be created per road patch. Set up the plots.. N! i3 M) q4 i" P  X
to setup  a1 ~# t- a4 I$ [% z3 f
  ca. B# T3 o& p6 w
  setup-globals2 H0 v6 G7 x5 h& N1 Q  P
4 o, C8 }# U9 W6 P1 u  L
  ;; First we ask the patches to draw themselves and set up a few variables4 [. d5 ]5 L6 Y6 u- H- `2 t
  setup-patches
: V+ k2 a* q! u7 ]  make-current one-of intersections2 J8 V5 H. h1 a$ j  p
  label-current
+ \9 o; o9 _) o9 ^$ Q3 V. \6 s+ A' w
  set-default-shape turtles "car"+ q, q, }% Y7 v

2 v9 B) ^! ?* s# t7 E! @0 ~  if (num-cars > count roads)5 Q& p9 p% E! |. D7 K
  [: Y7 u# e4 ~" x" ~6 R; k/ n* e8 M
    user-message (word "There are too many cars for the amount of "
0 t" D0 L, |) \  N                       "road.  Either increase the amount of roads ": C5 Y) h  F* B9 }; M+ {# \
                       "by increasing the GRID-SIZE-X or "
* M/ `5 Q; @9 a1 T* y9 r1 r                       "GRID-SIZE-Y sliders, or decrease the ", c0 Q( i& [7 Y4 B7 h) F' @& y! X
                       "number of cars by lowering the NUMBER slider.\n"1 ^7 r8 O1 f) V& I' F
                       "The setup has stopped.")
5 _# ^3 m! @' I# E0 {) D    stop) J: U! G1 ]) l' h$ X9 Y
  ]
# f7 E0 F( I' ~+ [, K
9 N; e4 N2 }, T+ g6 D+ `6 ?8 t" l  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color/ F5 w0 F: e) m8 H
  crt num-cars
. {$ G, g/ N3 ]" n, i$ ^% V  [/ ~! E7 }8 E, {! q
    setup-cars
! H8 R3 \- O% m$ [  }/ \. g    set-car-color# }& z4 Z# v* |) J
    record-data
1 l; L# T4 v4 n: X& J6 n. d6 m  ]
: o! n' U- E1 F* G5 T7 T) D/ ^' K! B
  ;; give the turtles an initial speed
  V# W& ~! d5 V/ Y9 V* ~( i* [8 d  ask turtles [ set-car-speed ]
  @* V  q  l* K" b) ^; U6 n7 t. Z, \4 _/ n: r) {
  reset-ticks
" c) U% D% }$ a% bend
6 X5 \7 ?. Q" S# W% Y- _4 N0 r' l0 I) I; H6 m9 p
;; Initialize the global variables to appropriate values
0 o) n; E0 a1 hto setup-globals
: p. u6 k4 b! _" P  v  set current-light nobody ;; just for now, since there are no lights yet
/ p- o: b: m; {' k& k$ X  set phase 0. N* j& d$ ^) p3 w) i5 E/ E
  set num-cars-stopped 04 Z( A0 l# S5 Y
  set grid-x-inc world-width / grid-size-x
. g. t: V' U) J0 m0 I5 F2 [  set grid-y-inc world-height / grid-size-y
1 T) |4 _! o9 R& b3 X
9 i/ r& @0 j/ F4 j* T  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
7 O6 I2 M, l1 |; h* `# q' u8 G# b. @  set acceleration 0.0999 y5 O) z: ~( |$ e4 J! {
end
7 `' ~' D, k. r* A) l
. J7 |9 N. k+ g) j2 z( q* r" H;; Make the patches have appropriate colors, set up the roads and intersections agentsets,: z$ V7 b3 G. u6 a$ y
;; and initialize the traffic lights to one setting3 u3 g  F7 w2 l# u
to setup-patches# W0 `0 R% z& r" P8 b' {1 F! r
  ;; initialize the patch-owned variables and color the patches to a base-color
" a# X) C2 i6 L' o5 K4 r  B5 i  ask patches
/ e' ?* N9 a- f$ P7 j, w( r  [
$ ^& u+ v: L, P8 F' h1 \8 K2 u  W; t    set intersection? false
: F0 e/ i- N8 Z* B" w; T    set auto? false3 R% ^+ S  U. c9 L# {
    set green-light-up? true
* X% n7 z3 w6 f9 ?" r5 m    set my-row -1
' Z6 G1 b: Q2 Z$ I7 {    set my-column -1
+ T0 u% I' C; q% E+ E( E  S    set my-phase -1
+ s1 {! _9 P5 F1 y5 z% V8 D: S    set pcolor brown + 3/ ?$ I- E! ^3 E7 `& }4 ^" ?8 G
  ]/ i; p$ a* Y# q# d* I2 m4 O
2 a* x& N# d# K3 I, k
  ;; initialize the global variables that hold patch agentsets
6 E6 k8 C  W( u8 t$ a- S* }( ?- U3 G+ S  set roads patches with) H/ S- y, V0 N6 ^( b/ G
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
% s, z2 u* J( b" f; X$ y& }    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]: i9 a. r3 @- V! J1 j- z7 z
  set intersections roads with
" m+ G+ [2 \% c& k3 C. a1 }/ E    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and% S  q: P: h+ D
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
# w; X9 s, K+ u0 `( o
7 W- y  v9 L: A9 C6 ]7 f* G; z+ l) |  ask roads [ set pcolor white ]
, @  Y8 p& }. B& ]/ K! a7 L* E    setup-intersections' J# [0 Q% @; x- n5 ^
end
7 I. k/ z2 a8 l- i* v9 \2 C, i# V其中定义道路的句子,如下所示,是什么意思啊?
8 |' h4 {2 z5 R set roads patches with
, l* h) t2 |, |) g& A/ o, f    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or6 X/ F" D" G6 k% _/ N' E( u
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]( F5 P9 @5 \+ P" t: M! d
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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