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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。7 A& Z5 h5 }! r+ A- `4 j& c
netlogo自带的social science--traffic grid这一例子当中,
  p# F& _' P# J* m/ n$ uglobals' G2 b' j0 d$ q5 z9 H
[
' [( b- _% \+ O4 Z  grid-x-inc               ;; the amount of patches in between two roads in the x direction
! K# S8 V+ ]# Z& K4 g  grid-y-inc               ;; the amount of patches in between two roads in the y direction
4 u- L+ h- ~# C* v* M$ g- O' E  acceleration             ;; the constant that controls how much a car speeds up or slows down by if; d& M8 ?; W% [7 f. k
                           ;; it is to accelerate or decelerate
' ]. m  T% Z+ F" X; L) U6 s  phase                    ;; keeps track of the phase
4 N* ~& j, W- X! X4 ^& p  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure: d* Q& [1 p4 V: }! [  a
  current-light            ;; the currently selected light
' i5 D! O( l! ?. }8 V. K
( W3 _  n- J; v9 H+ z  ;; patch agentsets
" z* q+ E) G; @  intersections ;; agentset containing the patches that are intersections
$ }: B7 i- w3 W; D2 w3 T  roads         ;; agentset containing the patches that are roads4 L  J# b: o4 h! f( V; r. i
]$ {5 c9 @1 C5 ?# d8 n

9 A8 R" {9 {+ p# o" |turtles-own! k/ C! D& d7 u3 {8 A
[3 v# M! z4 O2 m" S& S( `
  speed     ;; the speed of the turtle
: ^" q+ C8 r" k8 ?  up-car?   ;; true if the turtle moves downwards and false if it moves to the right! `# @2 Z, Q3 @
  wait-time ;; the amount of time since the last time a turtle has moved2 C' H; O4 M5 |
]
, I  r4 M% K: Y" @5 C7 B$ q$ s) U. {) t% I, U
patches-own' \2 Q* p/ g% m, U! K
[" U) `! S/ W. A/ B0 L' Q3 v
  intersection?   ;; true if the patch is at the intersection of two roads: w+ [' a# h2 @
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.# x& J6 h; _2 W: q9 X: `
                  ;; false for a non-intersection patches./ P; G( O/ i/ p8 ]) ~" {
  my-row          ;; the row of the intersection counting from the upper left corner of the
: ?: Z7 X. ~1 E7 s                  ;; world.  -1 for non-intersection patches.
( W: `, a" w: l( W2 A3 c+ o  my-column       ;; the column of the intersection counting from the upper left corner of the
, n% r- J- p. [+ W  R3 D- D                  ;; world.  -1 for non-intersection patches.
; ?+ f8 Y) b7 W+ m. ~$ v  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
8 X3 J% z- N; }5 u, G: e$ u+ A  auto?           ;; whether or not this intersection will switch automatically.0 n1 w2 q" F+ Z) E& o' a
                  ;; false for non-intersection patches.; k& t0 O9 r9 \6 x' V3 Q
]
; s4 l. z1 _+ z8 W( V& g& e7 m& L9 ]) Q+ G/ z* s: T

- h, M3 H* b2 G;;;;;;;;;;;;;;;;;;;;;;  K+ S: p* F4 U& W
;; Setup Procedures ;;
* I$ Z* N5 A7 n7 I6 S;;;;;;;;;;;;;;;;;;;;;;* ~8 k0 ?4 `, c

+ }0 M' }0 X/ P4 m: m2 L;; Initialize the display by giving the global and patch variables initial values.
/ A# e+ u+ u- @7 U  `3 y;; Create num-cars of turtles if there are enough road patches for one turtle to
* x, O2 W# J7 f;; be created per road patch. Set up the plots.
6 e7 g  g6 y" q- r2 Y, R0 Wto setup" @$ W3 p- h/ J. T% n
  ca, F: a1 R8 Y, g& N4 @
  setup-globals. {9 s- `; D5 ~( u" r

# b/ Q) o. Q; o  m& q! L" U  ;; First we ask the patches to draw themselves and set up a few variables# }; {* ~3 b4 I) T
  setup-patches, w* i2 g! P5 h* E! T
  make-current one-of intersections, k& V! [# Z) Q: W
  label-current8 A4 m& n7 H; w" a

/ i9 O* {7 n  w* ^2 _  set-default-shape turtles "car"
/ U2 x5 K, u( h3 S
1 U& u2 `3 m# [5 G! P8 k! H  if (num-cars > count roads)0 }6 ~; `- R! K0 v3 }0 W
  [
* J9 V7 n4 J( F% e" V    user-message (word "There are too many cars for the amount of "& ]3 S; J( y* y# y" h
                       "road.  Either increase the amount of roads "
* s" I- b! g' i1 E7 `& K% e                       "by increasing the GRID-SIZE-X or "! g  D1 ^  p( K  w
                       "GRID-SIZE-Y sliders, or decrease the "
- \' W! N6 Y0 K( |- K/ E                       "number of cars by lowering the NUMBER slider.\n"5 C0 D0 R6 {' w# J! a5 M5 a
                       "The setup has stopped.")
) ~! P6 U7 [  H% c; Y4 B    stop/ G* _5 {; @/ i# D
  ]$ r$ Z0 A. n' f2 E" h

' `9 ~; K* M  b: W9 m  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
0 ^2 o' r, {7 m  crt num-cars
% z+ T/ d4 a) H( @5 K8 k+ Q& K  [3 K4 T# \+ e4 @9 Q# ?& `+ u0 ~; y
    setup-cars3 ?  }" x+ k# a( S
    set-car-color
$ j6 B4 ]7 P, {: d    record-data
1 `( Z" F2 ]0 l" k7 o; A% j# m  ]
3 u' R( M9 ]8 |+ [# d1 ?/ a% {. z( t$ U4 Q* u: @' ]: Z9 t# ~
  ;; give the turtles an initial speed
7 ]7 j. P0 M/ e( s9 B  ask turtles [ set-car-speed ]
- f( U) O$ \) \+ L2 {* p4 e! ]! y0 w  s5 ^
  reset-ticks
3 ^8 _  v* q5 a! F; Eend
& l% i: k. i0 r9 [) b1 N& @( W" [( t8 A' q' z
;; Initialize the global variables to appropriate values5 z6 x0 `- C: a
to setup-globals
+ D2 u1 X3 i. T! T3 O. Y$ O  set current-light nobody ;; just for now, since there are no lights yet* g) ]' W/ I; m. ?/ G7 p
  set phase 0
! b) P, c# o9 g+ s4 n  set num-cars-stopped 0- D0 u+ \2 @" j# }( ]. n
  set grid-x-inc world-width / grid-size-x, Y- L) k' c2 s- a) S2 \
  set grid-y-inc world-height / grid-size-y; Z% M% U- \) T4 _

% {  C: x- d9 |& z! T4 Y( C  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary' E. y, ~+ ^( q0 l, U) _
  set acceleration 0.099# M% p( q2 a3 Y; K" ~, V
end
0 r9 |# \- I+ {; G
4 V( s% V* O3 B8 U2 j' `& a9 n4 M;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
# Y* V% O2 b' X0 G6 _6 T/ x;; and initialize the traffic lights to one setting8 n9 p# I  r- D* [( D$ w* ?
to setup-patches% Z+ D$ E- p: ?1 y6 ~
  ;; initialize the patch-owned variables and color the patches to a base-color
2 b. N" G; v  v; @1 W; H) A7 S  ask patches
1 e% i5 n2 {. a- K  |7 `- c  [
8 h2 P. U# G; Z5 F' K/ ~3 Q* o- p    set intersection? false
+ c% t, X: M) u' c0 _    set auto? false
- h' l# T" L! j/ K5 c# _    set green-light-up? true
% e& ^: `* I9 v' s: i    set my-row -1; E3 Y. L! G) y- R  t8 }/ U5 i' G$ B+ g
    set my-column -1, {" H$ N0 T0 W" j2 z
    set my-phase -1
: x, W5 E% {; f, a0 Q    set pcolor brown + 3& e5 j! v, {  Z# E( k* }3 o
  ]
% ^( K) N' k" k" t& k
: X8 m: T  E1 Z$ B) I# b. n  ;; initialize the global variables that hold patch agentsets
+ j# _2 n" B: P% \8 c5 d& W  set roads patches with9 k  U5 f! ?9 q  U8 L7 e9 ?9 f# l% K$ h% j
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
1 P* T: e: h. M0 f* i    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
6 L5 h! W& ^8 q- G  U& _/ a  set intersections roads with
9 ~) H# m- r+ P- W1 x" n0 G    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
2 S8 @4 O( m2 L# y4 f2 n. U! K9 G+ s    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]7 }6 c7 }) s6 e. C8 {( a

- t. M+ [  K4 l" A+ d/ W  ask roads [ set pcolor white ]
/ x. T+ x0 A. k" M) o    setup-intersections. u4 r" j! n8 j2 A
end/ a( j& X, R' x' ~# \. B: }. y
其中定义道路的句子,如下所示,是什么意思啊?" G  A3 p) `: |- D
set roads patches with! ^  Z$ _# K: u5 d3 `0 O' S! b+ K) u
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or1 l* M5 f& ~4 r' L
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]1 L9 v6 E2 Z) A. R. L2 \! f
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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