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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。
3 j/ x: z, V6 V0 D6 g! q; z; anetlogo自带的social science--traffic grid这一例子当中,
9 s$ q/ }, t2 T, A  mglobals
- P& [  G" Y. m[
( n% q6 M% D+ {6 d+ A  grid-x-inc               ;; the amount of patches in between two roads in the x direction2 I. D. K' j) w9 B+ m4 k/ ?# c
  grid-y-inc               ;; the amount of patches in between two roads in the y direction/ O, L8 i' z7 N  A* G
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if6 g, q0 D% w9 i) N+ X
                           ;; it is to accelerate or decelerate3 w) _2 C# J$ g
  phase                    ;; keeps track of the phase% J6 y% U1 m4 l/ M: e
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure* [7 {2 M9 Q7 E
  current-light            ;; the currently selected light0 K! d- J$ U8 j7 R: A8 |
" D. \' W# M0 Z3 }4 G/ N$ j
  ;; patch agentsets4 L# m2 |. o/ r
  intersections ;; agentset containing the patches that are intersections
0 k3 d1 t6 ]0 p' V- L1 a" O# `7 Z  roads         ;; agentset containing the patches that are roads
" j% y3 C$ l; r]
0 C+ g; v3 r% z3 z, z
5 k0 |& d% m$ d) h* o: I5 nturtles-own
! [( n  H& {+ s& @# B, u[
. w0 I! B6 V4 I' S% I  speed     ;; the speed of the turtle5 F+ t9 K- U5 Y  o/ ]  @( O; X
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right& X' G/ C4 J& o) s4 J
  wait-time ;; the amount of time since the last time a turtle has moved6 i# D& B$ s: D( l7 }- c$ [- c
]! E. J1 y+ m4 O) G
! E8 v" @( B3 Q" k% G% Q
patches-own
6 ^/ C& O7 D/ D# R9 l" l[
6 w7 r/ p) z6 G" {  Y  intersection?   ;; true if the patch is at the intersection of two roads* l7 q6 c" M- G0 W9 ~1 z: M& I! F
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.- z$ ]' \- r$ n5 A4 J0 w" {
                  ;; false for a non-intersection patches.
0 A! A+ D* A) b7 k7 o% \, L  my-row          ;; the row of the intersection counting from the upper left corner of the
* N' k* h* m$ |                  ;; world.  -1 for non-intersection patches.
, F/ Q) D; R6 D7 R8 d  j4 p  my-column       ;; the column of the intersection counting from the upper left corner of the
4 X& T- Z; [" O* P0 a                  ;; world.  -1 for non-intersection patches.% U1 v# a% R; I
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.: z- y5 y- l2 j( }( K
  auto?           ;; whether or not this intersection will switch automatically.
  E: P& \# a3 d! B0 a                  ;; false for non-intersection patches.* C6 y, G$ S( [, k- x4 o  E
]7 _% {+ |0 ^- R- ~8 a. F
/ N6 w2 n5 D5 j2 d( O

- Y( [8 |) n; [+ W;;;;;;;;;;;;;;;;;;;;;;1 E* t; N5 q5 P9 ]2 y
;; Setup Procedures ;;
* `; ^# U) \% l. {, K+ ?+ ?3 t7 q;;;;;;;;;;;;;;;;;;;;;;
8 B) @" A9 {# d8 d1 I+ P' @* C- A. N9 E
;; Initialize the display by giving the global and patch variables initial values.4 v; c7 |* c4 ^" w; d
;; Create num-cars of turtles if there are enough road patches for one turtle to
: C6 ~& P! _0 |9 R0 X6 u6 t* ?7 d;; be created per road patch. Set up the plots.
% l4 J& `& E- F+ V0 o) Bto setup
7 i$ h% }3 x  }! Z8 w& A- \& }  ca+ ^- @. O1 I* j! {
  setup-globals
. O: H" g9 ^! Z1 T( F9 l
3 l' H* w4 ?6 u7 L. d# }  ;; First we ask the patches to draw themselves and set up a few variables& K1 {2 F7 W2 y2 ]" U& i0 x1 P
  setup-patches
: Q3 P- O, M3 F. d8 \+ A  make-current one-of intersections
4 I! A$ B4 S3 L; l' @  label-current
! x! t; P# G. M( {
. Q5 c0 i7 Q7 L! I/ S  set-default-shape turtles "car"* H% [& a7 y% t, O& i
0 F$ h' {$ |- }
  if (num-cars > count roads)
7 K3 K; A6 P# l/ o  [" ^/ C2 u6 b: n" U- W8 B1 r% [$ R
    user-message (word "There are too many cars for the amount of "& z% w( l, r7 S/ R8 a
                       "road.  Either increase the amount of roads "  }' A' E9 G$ Y2 P5 }1 E& m
                       "by increasing the GRID-SIZE-X or "
) Q3 M+ ~$ j  F% W% Y                       "GRID-SIZE-Y sliders, or decrease the ", w2 P% f% n7 \8 D6 d7 L
                       "number of cars by lowering the NUMBER slider.\n"
# ?2 f/ b, g1 g; [4 n                       "The setup has stopped.")
$ i8 L- s5 _7 W$ C    stop1 \+ ^4 H, f; T- Y, k, J& I
  ]3 w: V" a4 z/ h6 {( Y, C

& N4 f3 {" V* _0 \9 _  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
7 F! S: g* t& `8 c# C* J/ U4 d  crt num-cars
! t7 t0 V8 T  S7 K  [
' L" M8 z4 p9 _0 N3 G: j    setup-cars8 w- ^5 r$ T" d! c9 X! c4 ~
    set-car-color& z8 B- C! M2 S: d" D4 N" m
    record-data
8 Z- s4 l! A" h; K3 n( t  ]" b5 I! q$ Q1 `

: z# Y/ T5 I! k+ V% `& ?  ;; give the turtles an initial speed
8 ^0 ^5 T& {' ?/ \  ask turtles [ set-car-speed ]5 u' m2 i1 k& T* F6 |
5 y% Y. H: D$ R$ q0 `. J' p8 Q
  reset-ticks
- ^  m) I" J- N2 g& V/ Send( A3 t5 f1 ~" ]' D9 B" o

, d. M) E3 A- ]" v+ p' Y;; Initialize the global variables to appropriate values) P' s6 y& s, W( L8 c2 u: ?
to setup-globals1 N5 V7 z$ O! U: \+ y
  set current-light nobody ;; just for now, since there are no lights yet
! b7 g. R3 ]7 G: I6 w; G  set phase 0
, m% P  @. `  I4 _' n9 @  W2 `  set num-cars-stopped 0
9 W8 t6 C6 S0 v! E- }# `  set grid-x-inc world-width / grid-size-x: p; O7 P3 A: D: O: R
  set grid-y-inc world-height / grid-size-y
0 q& O8 W' d! C! K1 r5 T+ N
/ J& H# W3 B: U! o' h; Z5 @3 }  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary" J* d% F3 a" s% _! ?
  set acceleration 0.099
5 S: i: ^* X: s" w/ w4 xend3 X1 ]$ s3 i1 n# ]' H, k
3 L. d+ Y; a& ~4 n. g
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
$ \' A6 Y' E4 N; k;; and initialize the traffic lights to one setting
- a* m/ P! B2 U2 j: H: Yto setup-patches
) [2 E! ]$ q4 T0 ^) c! K  ;; initialize the patch-owned variables and color the patches to a base-color
: V4 u6 W2 v: |8 K5 U9 [7 Q- f  ask patches
/ n" s: ]  e: u- S" _! ?$ \3 j  [; f8 g& W. Y% R- x7 V0 b# a
    set intersection? false
4 s' N! F& y, t, C7 O9 w/ G, K    set auto? false3 o7 M/ T: L0 ?( }$ j- H
    set green-light-up? true
" @/ Q0 T" }; a2 I- ^" c" S    set my-row -1
% I( `# G' j" O9 @    set my-column -1
  M' t+ L' g" s6 V9 G' X+ t" _( Y    set my-phase -12 p2 H  \" |) Y& ?  M
    set pcolor brown + 3& o8 B' a' o6 \5 p
  ]% w  m. M! h4 h) c" I, a
7 W' ?% P5 D! M) H& |, [4 x
  ;; initialize the global variables that hold patch agentsets9 a: a0 f8 U( K/ u9 c
  set roads patches with. c. L9 h  b9 d8 o  G0 U5 A
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
7 i9 x$ Z0 Z1 O2 r  Y1 z: n) |    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]7 Q! X. x- Q. G$ f- y9 V. B
  set intersections roads with
" w+ p, ~4 J, p9 d' w5 ?+ c8 N    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
$ ~8 \( f8 h- t4 W1 h    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
% M1 U8 x1 }! i4 n( A# \! H) O1 Y3 {" r
0 S6 X* N: B9 g' Q7 C( s  ask roads [ set pcolor white ]' {9 X# L3 o: @
    setup-intersections
" L, w2 C1 r- [+ T. Lend
2 e% P/ A5 x- j/ ]9 s其中定义道路的句子,如下所示,是什么意思啊?
7 L. {( @, E0 q; d5 d) { set roads patches with
. e/ {) I$ D% i" t    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or% I0 `8 c$ o; G( f' b
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]: z/ B  b0 z1 `) |& o
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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