gnuplot：应用数据文件中的颜色名称

Question

如何从数据文件中获取颜色名称？ 我没想到这会这么困难，但显然是这样。 为什么版本1和版本2给出错误的颜色？是否有更简单的方法无需使用版本3中的数组即可获得正确的颜色？ ...lc var仅适用于索引值，不适用于颜色名称。

### colornames from data
reset session

$Data <<EOD
1   40  orange
2   35  cyan
3   25  red
4   15  yellow
5   5   green
EOD

set yrange [0:]
set multiplot layout 3,1
MyColor = "black"
plot \
    $Data u 1:(MyColor=strcol(3),$2):(0.7) w boxes fs solid 1.0 lc rgb MyColor notitle,\
    $Data u 1:($2/2):(strcol(3)) with labels tc rgb "white" notitle

plot \
    for [i=1:|$Data|] $Data u (MyColor=strcol(3),$1):2:(0.7) every ::i-1::i-1 w boxes fs solid 1.0 lc rgb MyColor notitle,\
    $Data u 1:($2/2):(strcol(3)) with labels notitle

array MyColors[|$Data|]
plot \
    $Data u (NaN):(MyColors[$0+1]=strcol(3)) notitle,\
    for [i=1:|$Data|] $Data u 1:2:(0.7) every ::i-1::i-1 w boxes fs solid 1.0 lc rgb MyColors[i] notitle,\
    $Data u 1:($2/2):(strcol(3)) with labels notitle

print MyColors
unset multiplot
### end of code

Answer 1

我很惊讶这些方法中的任何一种都行之有效！

从文件中读取颜色信息的预期方法是

plot foo using 1:2:3 lc rgb variable

例如，参见在线演示rgb_variable.dem，该演示从数据文件rgb_variable.dat中读取颜色。

但是，假设第3列包含十六进制RGB（或ARGB）值， 而不是颜色名称的英语单词。 gnuplot识别的颜色词名称是name-> RGB映射的内置子集，该子集以前通常在系统文件X11 / rgb.txt中为X11提供。参见Wikipedia X11 colors。此列表的变体成为SVG标准的一部分。 gnuplot中包含的内容旨在用于交互式命令，而不是作为数据文件内容使用。

当然可以使用gnuplot数组和用户函数编写扩展名称-> RGB映射的脚本。例如：

$Data <<EOD
1   40  orange
2   35  cyan
3   25  red
4   15  yellow
5   5   green
EOD

array colorname  = ["orange", "cyan", "red", "yellow", "green"]
array colorvalue = [0xFFD700, 0x00DDDD, 0xDD0000, 0xFFFF00, 0x00DD00]
N = |colorname|
name2RGB(name) = sum [i=1:N] (name eq colorname[i] ? colorvalue[i] : 0) 

set yrange [0:]
set boxwidth 0.7
set style fill solid 1.0
unset key

plot $Data u 1:2:(name2RGB(strcol(3))) w boxes fc rgb variable

如果您经常处理此类文件内容，我想您可以将整个SVG或X11颜色名称表自动转换为一对gnuplot数组，并从〜/ .gnuplot初始化中加载它。

Answer 2

如果有人要按照@Ethan的建议使用查找表，这里是数组中的111种预定义gnuplot颜色（取自gnuplot手册）。

array ColorNames[111] = \
['white', 'black', 'dark-grey', 'red', 'web-green', 'web-blue', 'dark-magenta', 'dark-cyan', 'dark-orange', 'dark-yellow', \
'royalblue', 'goldenrod', 'dark-spring-green', 'purple', 'steelblue', 'dark-red', 'dark-chartreuse', 'orchid', 'aquamarine', 'brown', \
'yellow', 'turquoise', 'grey0', 'grey10', 'grey20', 'grey30', 'grey40', 'grey50', 'grey60', 'grey70', \
'grey', 'grey80', 'grey90', 'grey100', 'light-red', 'light-green', 'light-blue', 'light-magenta', 'light-cyan', 'light-goldenrod', \
'light-pink', 'light-turquoise', 'gold', 'green', 'dark-green', 'spring-green', 'forest-green', 'sea-green', 'blue', 'dark-blue', \
'midnight-blue', 'navy', 'medium-blue', 'skyblue', 'cyan', 'magenta', 'dark-turquoise', 'dark-pink', 'coral', 'light-coral', \
'orange-red', 'salmon', 'dark-salmon', 'khaki', 'dark-khaki', 'dark-goldenrod', 'beige', 'olive', 'orange', 'violet', \
'dark-violet', 'plum', 'dark-plum', 'dark-olivegreen', 'orangered4', 'brown4', 'sienna4', 'orchid4', 'mediumpurple3', 'slateblue1', \
'yellow4', 'sienna1', 'tan1', 'sandybrown', 'light-salmon', 'pink', 'khaki1', 'lemonchiffon', 'bisque', 'honeydew', \
'slategrey', 'seagreen', 'antiquewhite', 'chartreuse', 'greenyellow', 'gray', 'light-gray', 'light-grey', 'dark-gray', 'slategray', \
'gray0', 'gray10', 'gray20', 'gray30', 'gray40', 'gray50', 'gray60', 'gray70', 'gray80', 'gray90', \
'gray100']

array ColorValues[111] = \
[0xffffff, 0x000000, 0xa0a0a0, 0xff0000, 0x00c000, 0x0080ff, 0xc000ff, 0x00eeee, 0xc04000, 0xc8c800, \
0x4169e1, 0xffc020, 0x008040, 0xc080ff, 0x306080, 0x8b0000, 0x408000, 0xff80ff, 0x7fffd4, 0xa52a2a, \
0xffff00, 0x40e0d0, 0x000000, 0x1a1a1a, 0x333333, 0x4d4d4d, 0x666666, 0x7f7f7f, 0x999999, 0xb3b3b3, \
0xc0c0c0, 0xcccccc, 0xe5e5e5, 0xffffff, 0xf03232, 0x90ee90, 0xadd8e6, 0xf055f0, 0xe0ffff, 0xeedd82, \
0xffb6c1, 0xafeeee, 0xffd700, 0x00ff00, 0x006400, 0x00ff7f, 0x228b22, 0x2e8b57, 0x0000ff, 0x00008b, \
0x191970, 0x000080, 0x0000cd, 0x87ceeb, 0x00ffff, 0xff00ff, 0x00ced1, 0xff1493, 0xff7f50, 0xf08080, \
0xff4500, 0xfa8072, 0xe9967a, 0xf0e68c, 0xbdb76b, 0xb8860b, 0xf5f5dc, 0xa08020, 0xffa500, 0xee82ee, \
0x9400d3, 0xdda0dd, 0x905040, 0x556b2f, 0x801400, 0x801414, 0x804014, 0x804080, 0x8060c0, 0x8060ff, \
0x808000, 0xff8040, 0xffa040, 0xffa060, 0xffa070, 0xffc0c0, 0xffff80, 0xffffc0, 0xcdb79e, 0xf0fff0, \
0xa0b6cd, 0xc1ffc1, 0xcdc0b0, 0x7cff40, 0xa0ff20, 0xbebebe, 0xd3d3d3, 0xd3d3d3, 0xa0a0a0, 0xa0b6cd, \
0x000000, 0x1a1a1a, 0x333333, 0x4d4d4d, 0x666666, 0x7f7f7f, 0x999999, 0xb3b3b3, 0xcccccc, 0xe5e5e5, \
0xffffff]

添加： 为了它的价值，只是为了完整性和说明性... 下面的一些代码可生成有关预定义gnuplot颜色的概述（尽管以#rrggbb格式）。

### display all predefined gnuplot colors
reset session
set term wxt size 1000,700 enhanced  # or change to other terminal

array ColorNames[111] = \
['white', 'black', 'dark-grey', 'red', 'web-green', 'web-blue', 'dark-magenta', 'dark-cyan', 'dark-orange', 'dark-yellow', \
'royalblue', 'goldenrod', 'dark-spring-green', 'purple', 'steelblue', 'dark-red', 'dark-chartreuse', 'orchid', 'aquamarine', 'brown', \
'yellow', 'turquoise', 'grey0', 'grey10', 'grey20', 'grey30', 'grey40', 'grey50', 'grey60', 'grey70', \
'grey', 'grey80', 'grey90', 'grey100', 'light-red', 'light-green', 'light-blue', 'light-magenta', 'light-cyan', 'light-goldenrod', \
'light-pink', 'light-turquoise', 'gold', 'green', 'dark-green', 'spring-green', 'forest-green', 'sea-green', 'blue', 'dark-blue', \
'midnight-blue', 'navy', 'medium-blue', 'skyblue', 'cyan', 'magenta', 'dark-turquoise', 'dark-pink', 'coral', 'light-coral', \
'orange-red', 'salmon', 'dark-salmon', 'khaki', 'dark-khaki', 'dark-goldenrod', 'beige', 'olive', 'orange', 'violet', \
'dark-violet', 'plum', 'dark-plum', 'dark-olivegreen', 'orangered4', 'brown4', 'sienna4', 'orchid4', 'mediumpurple3', 'slateblue1', \
'yellow4', 'sienna1', 'tan1', 'sandybrown', 'light-salmon', 'pink', 'khaki1', 'lemonchiffon', 'bisque', 'honeydew', \
'slategrey', 'seagreen', 'antiquewhite', 'chartreuse', 'greenyellow', 'gray', 'light-gray', 'light-grey', 'dark-gray', 'slategray', \
'gray0', 'gray10', 'gray20', 'gray30', 'gray40', 'gray50', 'gray60', 'gray70', 'gray80', 'gray90', \
'gray100']

array ColorValues[111] = \
['#ffffff', '#000000', '#a0a0a0', '#ff0000', '#00c000', '#0080ff', '#c000ff', '#00eeee', '#c04000', '#c8c800', \
'#4169e1', '#ffc020', '#008040', '#c080ff', '#306080', '#8b0000', '#408000', '#ff80ff', '#7fffd4', '#a52a2a', \
'#ffff00', '#40e0d0', '#000000', '#1a1a1a', '#333333', '#4d4d4d', '#666666', '#7f7f7f', '#999999', '#b3b3b3', \
'#c0c0c0', '#cccccc', '#e5e5e5', '#ffffff', '#f03232', '#90ee90', '#add8e6', '#f055f0', '#e0ffff', '#eedd82', \
'#ffb6c1', '#afeeee', '#ffd700', '#00ff00', '#006400', '#00ff7f', '#228b22', '#2e8b57', '#0000ff', '#00008b', \
'#191970', '#000080', '#0000cd', '#87ceeb', '#00ffff', '#ff00ff', '#00ced1', '#ff1493', '#ff7f50', '#f08080', \
'#ff4500', '#fa8072', '#e9967a', '#f0e68c', '#bdb76b', '#b8860b', '#f5f5dc', '#a08020', '#ffa500', '#ee82ee', \
'#9400d3', '#dda0dd', '#905040', '#556b2f', '#801400', '#801414', '#804014', '#804080', '#8060c0', '#8060ff', \
'#808000', '#ff8040', '#ffa040', '#ffa060', '#ffa070', '#ffc0c0', '#ffff80', '#ffffc0', '#cdb79e', '#f0fff0', \
'#a0b6cd', '#c1ffc1', '#cdc0b0', '#7cff40', '#a0ff20', '#bebebe', '#d3d3d3', '#d3d3d3', '#a0a0a0', '#a0b6cd', \
'#000000', '#1a1a1a', '#333333', '#4d4d4d', '#666666', '#7f7f7f', '#999999', '#b3b3b3', '#cccccc', '#e5e5e5', \
'#ffffff']

#convert a hex string to dec format
hex2dec(hex)=int('0x'.hex)
# get decimal number for R,G,B
R(ColorCode) = hex2dec(ColorCode[2:3])
G(ColorCode) = hex2dec(ColorCode[4:5])
B(ColorCode) = hex2dec(ColorCode[6:7])

# "empirical" formula do decide whether using a white or a black label on the colored background
LabelColor(ColorCode) = \
   (R(ColorCode)+G(ColorCode)*1.5+B(ColorCode)*0.5)/3. > 127 ? "#000000" : "#ffffff"

# Settings
PosYOffset = 4.5
SizeX = 0.7
SizeY = 5
Cols = 10

# loop for placing colored rectangles and labels
do for[i=1:111] {
  PosX = i%Cols
  PosY = floor(i/Cols)*Cols
  set object i rectangle at PosX, PosY size SizeX,SizeY fc rgb ColorNames[i]
  set label i at PosX, PosY+PosYOffset ColorNames[i] center font ",9"
  set label 200+i at PosX, PosY ColorValues[i] tc rgb LabelColor(ColorValues[i]) center font ",9"
}

set title "Predefined colors in gnuplot"
set xrange[-0.5:9.5]
set xtics 1
set link x2 via x inverse x
set x2tics 1

set yrange[119:-5] reverse
set ytics 10
set link y2 via y inverse y
set y2tics 10

# plot invisible dummy data
plot '-' w p ps 0 not
0 0
e
### end of code

Answer 3

这是另一种方法，使用从数据文件或数据块自动生成的调色板。 这样，您就不必关心十六进制数字或任何数字或颜色代码。 您只需要确保您没有使用无效的颜色名称即可。除非长数据集的调色板长度没有限制，否则此方法应该起作用。

### colornames from data
reset session

$Data <<EOD
1   40  red
2   35  orange
3   25  yellow
4   20  greenyellow
5   15  web-green
6   12  web-blue
7   10  violet
EOD

MyPalette = '('
set table $Dummy
    plot $Data u (MyPalette = MyPalette.sprintf('%d "%s", ',$0,strcol(3))) with table
unset table
MyPalette = MyPalette[:strlen(MyPalette)-2].')'
set palette model RGB defined @MyPalette
unset colorbox 

set yrange[0:]
plot $Data u 1:2:(0.7):0 w boxes fs solid 1.0 lc palette notitle,\
    '' u 1:($2/2):(strcol(3)) with labels notitle
### end of code

Sample script of useFirstColumnAsDomain