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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。1 q8 \" r) @& K& n8 q" V/ S1 U
netlogo自带的social science--traffic grid这一例子当中,9 ?4 [, }* C; o$ D5 t) `  A
globals
0 l2 m0 |% X" j: E$ ~[
2 n+ a; Q+ L' }) v0 @: E. v  grid-x-inc               ;; the amount of patches in between two roads in the x direction
6 H5 b2 r1 T  b+ B" K  grid-y-inc               ;; the amount of patches in between two roads in the y direction
7 c; s; z% u- A; o  i$ l  acceleration             ;; the constant that controls how much a car speeds up or slows down by if! ]5 X$ B: v9 }! [; S3 i+ x( J( D- z
                           ;; it is to accelerate or decelerate
% \  g3 F# K, }5 p  phase                    ;; keeps track of the phase
0 y- B5 F5 \( L  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure7 S0 k6 O# U% A8 J2 V
  current-light            ;; the currently selected light
/ ]# A0 }  G- `0 Q$ G6 I$ T" G( F5 z+ G
  ;; patch agentsets
& n; F7 r- H1 a- J  intersections ;; agentset containing the patches that are intersections/ ?6 K$ }3 `3 e: v
  roads         ;; agentset containing the patches that are roads
& I5 g' G- p2 b; A& J1 T3 F) M]* N1 k4 g5 \2 t# t0 M; ?
) H+ g/ E: D8 ]5 z4 O; s
turtles-own4 m! Q* \* f" `6 J2 k) s, _
[
" ^2 `  D3 U' g3 x+ s  speed     ;; the speed of the turtle
5 _  ~  V. A: C! [1 m  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
7 C& H/ m6 \5 z  wait-time ;; the amount of time since the last time a turtle has moved, o  {/ [8 ^) E, U3 l3 j" e' Z
]) a! h" T+ i) G+ Z

" Z  {5 u5 P7 K9 \patches-own
- w$ r6 O  ?) K5 [: _# w! k[7 n8 }! o' G+ K
  intersection?   ;; true if the patch is at the intersection of two roads
5 T% `3 g7 a4 n: i0 c# ]+ ^& r  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.5 N% \1 ?# k' d" B0 b) _  a
                  ;; false for a non-intersection patches.
* k, {  I7 E) k2 U- v! W2 \% ~7 N  my-row          ;; the row of the intersection counting from the upper left corner of the! z" ?# u- C# h! ~' A! {$ M) g/ U
                  ;; world.  -1 for non-intersection patches.
" O1 Y5 `$ D2 L, M  my-column       ;; the column of the intersection counting from the upper left corner of the
5 U7 \6 ]( p* L8 J9 ~                  ;; world.  -1 for non-intersection patches.) a" J) h$ b8 `( a0 T( [8 V& E8 D9 l
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.# w, I8 v/ T0 Z, |, {) Y' Z
  auto?           ;; whether or not this intersection will switch automatically.3 `$ G; K, c) W- [" o, ?
                  ;; false for non-intersection patches.
: @  J- n9 ^8 Z  y! {! \: l, i7 S]# ^! {) o. {' E1 A2 ]) C+ b
, U8 J% U. m6 O$ B3 O) [! ?
" L1 v7 l3 e3 V+ F( D
;;;;;;;;;;;;;;;;;;;;;;  R: @! \0 V2 [0 X9 r
;; Setup Procedures ;;( S+ ^% c8 _2 y
;;;;;;;;;;;;;;;;;;;;;;
, q6 N6 w8 l5 z  x' D6 {
( r, }9 `1 j1 z$ l4 U& R6 R;; Initialize the display by giving the global and patch variables initial values.
! K8 ~! |; T8 t# _;; Create num-cars of turtles if there are enough road patches for one turtle to) L' q+ Q* v1 b, k4 {' v
;; be created per road patch. Set up the plots.$ }5 ]5 [' f! J3 ~: i% x, U4 H
to setup! B  G$ ?1 x  V' u' f
  ca
7 C  T) u, G: o& Y! D7 C  setup-globals
+ u# \) q- A, ?. u' q7 x) U9 u! x: u1 O5 E2 I
  ;; First we ask the patches to draw themselves and set up a few variables
7 Q2 f6 o! ]3 \* S' A' s& p; X  setup-patches
( ]0 w0 A% }) a2 D- u  J" {  make-current one-of intersections- l* c# v* l8 Y3 H
  label-current. L3 L. q9 b$ Q
' m- X2 b& Z0 k
  set-default-shape turtles "car"% b9 X2 z2 w* w. b  i* C
! t. H2 T% L) N1 _1 _1 P6 w5 X
  if (num-cars > count roads)
4 y$ A. L5 _' |: l2 D/ [7 V  [+ `' ]- E0 L3 {
    user-message (word "There are too many cars for the amount of "
" e7 |0 @4 P( h8 @" p5 L* N: W' [                       "road.  Either increase the amount of roads "
5 O8 i" ]7 x2 ~4 `                       "by increasing the GRID-SIZE-X or "( a. U% U; l9 t
                       "GRID-SIZE-Y sliders, or decrease the "  P, \" `. a4 }: P) l- S2 B
                       "number of cars by lowering the NUMBER slider.\n"2 s( _6 }$ l8 b% k
                       "The setup has stopped.")$ [/ {9 x5 K3 d! E8 r; B  K
    stop
7 M' D0 P$ u# h! h" u+ D& p0 L  ]: _7 U3 @) h- y  }( U; B
' n4 L/ o1 B5 \$ Z/ P9 V$ D" O& }
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color: |! @9 ~% X; X0 @5 T' U
  crt num-cars
! F, x1 e8 N7 H5 n; P2 z' O  [2 ]8 {3 \" m3 c  o5 y
    setup-cars, l/ z4 [5 L4 S# ?! i
    set-car-color
8 E  ^" q  P% y9 w6 k/ G    record-data
: ?& M6 d  Y+ @/ _: M: H  ]3 p. T: o" x7 `1 w
5 o" `6 c* E- S
  ;; give the turtles an initial speed3 h5 d$ l2 e3 U
  ask turtles [ set-car-speed ]6 O9 X' b4 S1 q8 ?

' }2 n/ U1 S4 }) f* y' F) [, r7 I  reset-ticks
+ q7 M' W0 }  c. n% \* aend4 E: e& M  U% ^7 v

, |; L( T; r& j. |;; Initialize the global variables to appropriate values; \& t0 t& l# `6 R3 m3 c1 M$ N
to setup-globals
* n) e1 a6 c5 ?0 A, x! F% a3 n  set current-light nobody ;; just for now, since there are no lights yet4 @( s# k0 ]% j7 Z- X- a# N
  set phase 0
0 H1 n- K) x( q6 j0 H6 ]) [  set num-cars-stopped 0
+ @8 B# e- T: A5 c# b+ G9 M+ L  set grid-x-inc world-width / grid-size-x# X* G3 n& K5 k& X3 O5 [; p
  set grid-y-inc world-height / grid-size-y5 j( F+ }, x, [, ~% E% m+ O! M  u

6 i( ^6 h: \9 u  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary* h) O2 u/ e2 c1 ]
  set acceleration 0.099
+ b& L- e# I* Q7 Bend
) \0 M& x9 ]5 }! X. ]% U. ?& G/ }4 y) H- f" f( B
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,+ ^  \- n1 r# C  o
;; and initialize the traffic lights to one setting5 X( @; u- n' l! d2 T
to setup-patches  L* \+ g2 t" P# h- Y
  ;; initialize the patch-owned variables and color the patches to a base-color
# r& Q# W+ z# q5 _9 L  ask patches  h7 H7 F* W4 p: R1 v3 z8 U
  [
* a1 u- p1 h, p. r    set intersection? false9 N1 q4 v) I  i3 K, v- I
    set auto? false1 Q' g; I4 H7 r6 ]# s1 D
    set green-light-up? true7 P: k* q0 {" K$ K  L. \) P
    set my-row -1
& L# x3 r6 D5 p' G2 m7 n: [    set my-column -1  [4 R  }9 E3 u5 ]& g. m2 \
    set my-phase -1- _, {3 e  Y7 B
    set pcolor brown + 3/ B. G6 {* f/ O( g0 c: g
  ]
- j0 l% H  O% k; u3 z2 y( X8 ~' a( A: Z7 X% W7 K
  ;; initialize the global variables that hold patch agentsets* l4 H7 z5 h' y3 h, g1 O
  set roads patches with7 f' Y8 J9 }2 o/ R$ j! `
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
) \1 a- s& c3 d1 l$ l5 g" N    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
+ S; N& \4 P5 Z" j  set intersections roads with
5 j% x" J+ j" `+ l    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
# A8 H% B* ?/ N    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]# J1 ~( O9 |7 B, M

% n0 c% B4 d: x4 t  ask roads [ set pcolor white ]" V6 U% G7 r# `9 }+ K
    setup-intersections% C& c  q. M8 ^4 y% U0 K
end  U0 N* U& n5 E8 a# E( U$ Y  S
其中定义道路的句子,如下所示,是什么意思啊?1 K% z& \8 l: j; V2 M, o6 \# _
set roads patches with: h" u  b+ R* H8 c3 g% S
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
! S) m/ e4 {* s& w7 }- t: E    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
/ Z8 Q  W7 O, W/ e# D3 M/ @) L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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