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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 ~( s6 V, Q8 j7 O/ K: z6 i- L
netlogo自带的social science--traffic grid这一例子当中,/ e. Y- m1 _; e  y( |6 x
globals
0 n& X) |+ j, g; X* L4 R[5 W2 Y+ M' j, C7 n2 R7 R
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
8 b  U- p: M& @2 O  grid-y-inc               ;; the amount of patches in between two roads in the y direction
6 H6 q2 a2 i( [) j  T  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
! o# c! X  P- F. p                           ;; it is to accelerate or decelerate, ?5 j3 C# V# e. `. q8 {3 z
  phase                    ;; keeps track of the phase7 N* f3 ^! E$ Q4 k7 S* a; W
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure8 G$ e! P4 |; b5 |
  current-light            ;; the currently selected light& `7 Z4 J2 q! H4 S5 `

# e3 V0 U( r* D% f. @3 b0 N  ;; patch agentsets, y9 s$ x3 r. s) K0 @% [4 P; I
  intersections ;; agentset containing the patches that are intersections2 S. {3 K( H1 x0 b; M
  roads         ;; agentset containing the patches that are roads
2 [# \* Q! A2 v]
/ n% C6 {* Z6 h% O+ _0 }2 s
2 @- l3 U0 {5 d# T# w3 [2 Z. ^9 S2 Bturtles-own
0 n% w( u. D0 x- s* [6 `[+ _: y4 m7 p- v: G8 ^( |( J* f
  speed     ;; the speed of the turtle
: a% }  c* v* c) y  up-car?   ;; true if the turtle moves downwards and false if it moves to the right* D" v  B- s* x
  wait-time ;; the amount of time since the last time a turtle has moved
& k5 m  c0 ~. L8 p]
* p7 l( J* t: N: j9 K# c0 A% T% J, b% D% ?5 Q0 `
patches-own  |4 A$ x; ?6 Q/ a9 {+ W/ D$ H
[
' O0 O2 s/ T; l1 I0 m& j  intersection?   ;; true if the patch is at the intersection of two roads
7 R# e: {: N- b; ?3 i, C  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.( ~! i, g6 a/ [6 s5 U
                  ;; false for a non-intersection patches.# m8 E) i5 z+ i; D1 }5 D
  my-row          ;; the row of the intersection counting from the upper left corner of the
9 n4 _0 q. `% s0 T                  ;; world.  -1 for non-intersection patches.) K8 M4 N0 `! f/ g8 s4 y& u
  my-column       ;; the column of the intersection counting from the upper left corner of the
. K1 h4 B, O8 Q. g: g+ V6 g                  ;; world.  -1 for non-intersection patches.
$ O9 c; M! j  U. G4 n3 g  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
. B# J' p- N$ T# b: C2 A( u  auto?           ;; whether or not this intersection will switch automatically.9 E+ {$ @5 p) T! {: h2 S
                  ;; false for non-intersection patches.
# K8 a3 B1 m* R: ]& W7 P]+ `) G  o! N3 U

& N2 E" a: ^- L7 n* O8 J, ]& }1 x0 B, y6 H# c
;;;;;;;;;;;;;;;;;;;;;;
; R$ R# L7 d5 A;; Setup Procedures ;;" ?: }$ V3 J* b5 Z' k' \
;;;;;;;;;;;;;;;;;;;;;;
! n" ^& |8 g8 K' ?+ N8 ~" `7 c: q" J6 {% I. a! D
;; Initialize the display by giving the global and patch variables initial values.
3 J* C2 t: }9 q  I2 U7 d7 a4 E1 };; Create num-cars of turtles if there are enough road patches for one turtle to( R$ z8 k! ?& A# l7 R( p
;; be created per road patch. Set up the plots.
' r! a' b& {3 `, A' r+ k. uto setup
# j4 K5 n" ?+ p/ r  ca& t5 a# f6 y$ H0 I* Q0 l7 `
  setup-globals1 w+ W5 f/ z6 Z& @* K) a
3 J) G1 m5 E( ~. }, h
  ;; First we ask the patches to draw themselves and set up a few variables' A6 H8 N3 }1 t1 G! B
  setup-patches- P3 ]5 V) R7 I$ V
  make-current one-of intersections# p& c( P& a  b! ]6 o2 o' T
  label-current9 g( @: t. q3 f5 a

1 n5 P2 ~. D' N9 i  set-default-shape turtles "car"9 t+ n( u' a, E! B# w9 j- X

8 k: `0 o0 s* _6 `4 l  if (num-cars > count roads)6 \) P9 v& d1 y. |8 K
  [) r9 f2 H7 p- v: C: m
    user-message (word "There are too many cars for the amount of "
1 F% {: \: b- ?9 V. V* l3 e                       "road.  Either increase the amount of roads "
0 G3 E- G, i4 _5 L9 Q2 x                       "by increasing the GRID-SIZE-X or "
4 L$ q# `: y8 f6 k8 m4 r/ b$ t                       "GRID-SIZE-Y sliders, or decrease the "2 y, s) G. w( \, A+ E0 M+ O
                       "number of cars by lowering the NUMBER slider.\n"8 K5 d$ U6 Z& @2 P+ \* p
                       "The setup has stopped.")
0 y1 ?+ T( I( F$ l, `8 D+ s    stop& l$ u/ _7 M, f% L3 m/ U* @' M
  ]- r2 \7 z. ~; p7 A0 q
5 g( o8 U; X; @' Z
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color: H8 {/ H) d5 t/ i( M: j! ], r
  crt num-cars
3 N' z+ C' Q+ V1 Q1 K9 |4 e/ Y1 {  [
/ e$ n& ^# W: O1 C) J" H1 m0 M( g    setup-cars
6 \- D6 }- g! s/ M: ^2 N: M( y    set-car-color0 [; t3 X& l" W6 d) Z
    record-data
- C+ P7 O% |* Z* D  ]
0 ~$ d% }2 o+ }( W3 i
& ~% t1 _! m7 B7 d/ x8 u  ;; give the turtles an initial speed
% L0 I( K* e# P' K: f/ L' M  ask turtles [ set-car-speed ]$ I1 f8 q9 c' Z) L& F5 @" O
$ |, ?, x- q6 d
  reset-ticks) e4 Y3 P6 M# I; u! I$ u
end* c! K8 t9 A( X4 C& C5 g% w: l

. |7 E" k0 P7 l8 ]" F;; Initialize the global variables to appropriate values* z4 Q1 a. X8 Y* z" @
to setup-globals9 x( f% x+ Y2 R4 [  Z1 ~% c* [
  set current-light nobody ;; just for now, since there are no lights yet/ c. ~" _9 K1 `' Z  h* O/ d& r
  set phase 0
) z0 b; j9 R' g& ^; ]' f  set num-cars-stopped 0
5 {$ y( @- S& Q1 e/ a: n  set grid-x-inc world-width / grid-size-x9 H# s# P( ]9 d& w: C& K
  set grid-y-inc world-height / grid-size-y1 o) S1 u; G8 Q8 d
: C& K# q4 @8 m; ^
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
# ]0 o- Q. _2 C  set acceleration 0.099
5 g( @, a: i/ I5 o+ B) o+ bend7 D- j2 [, `$ d3 L" q) M
+ y# P6 A& w" X& T1 [6 C
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
% l$ A/ {8 K9 h  Y, l- z  C;; and initialize the traffic lights to one setting( u* y1 g: |# a( @% \
to setup-patches3 R7 D  @8 E8 a6 `( M6 A$ ?) Z
  ;; initialize the patch-owned variables and color the patches to a base-color
( c* t9 V# s1 b, ?/ ^1 G, n, U  ask patches
* @  \' w# l3 d; r+ Q  [
1 d  N6 N5 v8 Y    set intersection? false
# o  e7 u! z2 q    set auto? false% }) j0 f# w1 L  e: ]. Q
    set green-light-up? true) O! B, V, v8 t5 S* L7 P# r% m
    set my-row -1% d: C: e7 g7 n7 J8 \$ C; g
    set my-column -1; v) n2 X1 W5 c: B
    set my-phase -1
0 C9 R7 O9 B& K* h5 Q: Y    set pcolor brown + 3
4 k/ T" {6 d. `! n* h0 b/ Q  ]3 j& v; T6 G, {& u' l

3 I4 @3 o, r" ]7 m$ `  ;; initialize the global variables that hold patch agentsets
7 |* e4 \9 @' [7 I5 E  ?; g1 D8 e  set roads patches with4 V) f% r; T+ T. g' N
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
$ p2 m* B: i" Y- E9 {4 E9 f( l  ~1 t    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]4 h0 A1 N& }9 i3 N
  set intersections roads with
) s9 T  U% w5 u9 h    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and( c) W: ]4 s+ ~
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
2 ^- S# A  ]3 h" y' s; ]0 r7 e  v5 a7 r- Y+ N
  ask roads [ set pcolor white ]
  }8 C/ x( H# p& w, q    setup-intersections
' y2 _: x, q5 Y3 S2 f3 J0 J8 ?7 Lend
* b5 f) z, `% m/ o其中定义道路的句子,如下所示,是什么意思啊?8 _, F6 t) M  ?( [+ ?# X
set roads patches with  M& Z8 M9 K- @, \
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or- k0 w- c3 |# l+ @# p
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
1 Z8 H* Z; x2 q3 q! K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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