使用风速和度数绘制风场

Question

如何使用下面的代码像这张地图一样绘制风场？

Time  Temp Wind speed Wind direction Pressure
 202000200   10.8836    2.4982   90.5014   80.7499
 202000300    9.8425    2.6553   41.5163   90.0338
 202000400    9.5351    2.4581   40.1018   80.5542
 202000500   12.5231    4.1907  120.2293   84.4332
 202000600   17.2069    3.1405  177.5542   87.0220
 202000700   10.7297    5.5018  269.7194   81.5804
 202000800    6.0049    4.2357  309.8655   68.6385
 202000900    8.3194    2.5722   81.6993   78.4679
 202001000    8.5940    4.2101   41.0358   84.9437
 202001100    7.3084    3.8480  217.5551   70.2860
 202001200    5.5046    3.0959  158.0296   68.9129

Answer 1

我不清楚第一列是如何解释的（年份 + 什么？）所以为了说明的目的，我只将最后 4 位数字作为 x 坐标。
定义箭头形状的选项有很多。请参阅“帮助设置样式箭头”。
绘图样式 with arrows 的数据字段为 x:y:length:angle

\

set angle degrees
unset key
set xzeroaxis
set xrange [0:*]
set title "Wind speed and direction"

SCALE = 10.

plot $WIND using ( - 202000000) : (0) : ( * SCALE) : 4 with arrows noborder

Answer 2

这里是 gnuplot 5.2 版本。您可以使用绘图样式 with vectors.

特别提到的应该是：

set size ratio -1 这使得 x 和 y 的比例相同，例如45 度角实际上显示为 45 度角（检查 help size）。取决于 x 和 y 范围和终端大小的系数 SCALE 会自动调整。
为了确保键（或图例）箭头的比例正确，我没有使用标准键（因为我不知道它相对于坐标的比例是多少），而是一个箭头和一个标签需要一些额外的编码。

代码：

### plot wind directions (gnuplot 5.2)
reset session

$Data <<EOD
# Time  Temp Wind speed Wind direction Pressure
 202000200   10.8836    2.4982   90.5014   80.7499
 202000300    9.8425    2.6553   41.5163   90.0338
 202000400    9.5351    2.4581   40.1018   80.5542
 202000500   12.5231    4.1907  120.2293   84.4332
 202000600   17.2069    3.1405  177.5542   87.0220
 202000700   10.7297    5.5018  269.7194   81.5804
 202000800    6.0049    4.2357  309.8655   68.6385
 202000900    8.3194    2.5722   81.6993   78.4679
 202001000    8.5940    4.2101   41.0358   84.9437
 202001100    7.3084    3.8480  217.5551   70.2860
 202001200    5.5046    3.0959  158.0296   68.9129
EOD

set size ratio -1
set angle degrees
myTimeFmt = "%Y%j%H"

# automatic determination of "optimum" value for SCALE with given data and terminal size
plot x  # plot dummy graph otherwise GPVAL_TERM_XSIZE and GPVAL_TERM_YSIZE will be undefined
stats $Data u (timecolumn(1,myTimeFmt)):(*sin()) nooutput
SCALE = (STATS_max_x-STATS_min_x)/(STATS_max_y-STATS_min_y)/GPVAL_TERM_XSIZE*GPVAL_TERM_YSIZE

set title "Wind speed and direction"
set format x "%j" timedate
set xzeroaxis lt -1
set grid xtics,mxtics lt -1, lt 0
set format y ""
unset ytics

# Legend arrow in correct scale
Speed = 2.0
KeyPosX = 0.8    # relative to graph
KeyPosY = 1.08   # relative to graph
set style arrow 1 filled size graph 0.015,15 fixed lc rgb "blue"
set arrow 1 from graph KeyPosX, graph KeyPosY rto first Speed*SCALE,0 as 1
set label 1 "2 m/s" at graph KeyPosX,graph KeyPosY right offset -1,0

plot $Data u (timecolumn(1,myTimeFmt)):(0):(SCALE**cos()):(SCALE**sin()) \
    w vectors as 1 notitle
### end of code

结果：

使用风速和度数绘制风场

Draw wind field using wind speed and degree

gnuplot