更改 ggplot 图例渐变答案

【问题标题】：Changes ggplot Legend gradient更改 ggplot 图例渐变
【发布时间】：2021-02-12 04:38:26
【问题描述】：

我有这个关于不同基因型平均增长率的数据集：

Genotype  desv  mean  Rank
   <fct>    <dbl> <dbl> <dbl>
  ENG2    0.345  4.29     7
  ENG20   0.255  3.90     9
  ENG22   0.185  4.19     8
  ENG24   0.341  3.84    10
  ENG25   0.195  3.51    12
  ENG3    0.267  4.38     6
  ENG32   0.262  3.61    11
  ENG4    0.223  4.49     4
  ENG5    0.359  5.13     2
  ENG7    0.122  4.49     5
  ENG8    0.182  4.90     3
  ENG9    0.459  5.28     1

下面的代码可以制作一个ggplot图：

ggplot(growth2)+
  geom_col(aes(x=Rank, y=mean, fill=mean), width=0.7, color="Black")+
  geom_errorbar(aes(x=Rank, ymin=mean-desv, ymax=mean+desv), position = position_dodge(width=0.9),width=0.4, alpha=1)+
  theme_classic()+
  theme(axis.text.x=element_text(angle = 90, hjust =2, vjust = 0.5, family="sans", size=12, color="Black"))+
  theme(axis.ticks.x = element_blank())+
  xlab("")+
  ylab(expression(paste("AGR (cm "," ", year^-1,")", sep="")))+
  theme(axis.line.x = element_blank())+
  theme(axis.text.y=element_text(family="sans", size=12, color="Black"))+
  theme(axis.title.y= element_text(margin=margin(t=0, r=10, b=0, l=0)))+
  scale_y_continuous(breaks=c(0, 1, 2, 3, 4, 5, 6), limits = c(0,6))+
  scale_fill_gradient(low="red", high="green", name="")+
  geom_hline(yintercept = 0, color="Black")+
  theme(legend.position = c(0.5,1), legend.direction = "horizontal")+
  theme(legend.text = element_blank())+
  theme(plot.margin = margin(1,0,0,0, unit = "cm"))+
  scale_x_continuous(breaks=c(1,2,3,4,5,6,7,8,9,10,11,12),labels = c("ENG 9 ", "ENG 5 ", "ENG 8 ", "ENG 4 ", "ENG 7 ", "ENG 3 ", "ENG 2 ", "ENG 22", "ENG 20", "ENG 24", "ENG 32", "ENG 25"))

然而我的传奇并不是我想要的样子。绿色部分（高增长率）应该在左边。我在 guides_legend 中尝试了相反的操作，但没有成功。我也希望图例的大小占据图表的长度。我在 ggplot 中没有发现任何关于图例长度的争论。

有人可以帮我吗？或者指出是否可以更改这些图例。

【问题讨论】：

标签： r ggplot2 graphics

【解决方案1】：

如果是渐变比例，您必须使用guide_colorbar(reverse = TRUE) 而不是guide_legend：

颜色条的with可以通过选项barwidth = grid::unit(750, "pt"))设置

library(ggplot2)

ggplot(growth2) +
  geom_col(aes(x = Rank, y = mean, fill = mean), width = 0.7, color = "Black") +
  geom_errorbar(aes(x = Rank, ymin = mean - desv, ymax = mean + desv), position = position_dodge(width = 0.9), width = 0.4, alpha = 1) +
  theme_classic() +
  theme(axis.text.x = element_text(angle = 90, hjust = 2, vjust = 0.5, family = "sans", size = 12, color = "Black")) +
  theme(axis.ticks.x = element_blank()) +
  xlab("") +
  ylab(expression(paste("AGR (cm ", " ", year^-1, ")", sep = ""))) +
  theme(axis.line.x = element_blank()) +
  theme(axis.text.y = element_text(family = "sans", size = 12, color = "Black")) +
  theme(axis.title.y = element_text(margin = margin(t = 0, r = 10, b = 0, l = 0))) +
  scale_y_continuous(breaks = c(0, 1, 2, 3, 4, 5, 6), limits = c(0, 6)) +
  scale_fill_gradient(low = "red", high = "green", name = "", guide = guide_colorbar(reverse = TRUE)) +
  geom_hline(yintercept = 0, color = "Black") +
  theme(legend.position = c(0.5, 1), legend.direction = "horizontal") +
  theme(legend.text = element_blank()) +
  theme(plot.margin = margin(1, 0, 0, 0, unit = "cm")) +
  scale_x_continuous(breaks = c(1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12), labels = c("ENG 9 ", "ENG 5 ", "ENG 8 ", "ENG 4 ", "ENG 7 ", "ENG 3 ", "ENG 2 ", "ENG 22", "ENG 20", "ENG 24", "ENG 32", "ENG 25"))

【讨论】：

【解决方案2】：

为了切换图例中的颜色顺序，我交换了这一行的颜色名称：

  scale_fill_gradient(low="green", high="red", name="")+

为了在整个 x 轴上加宽图例，我在您的 theme() 之后使用了 legend.key.width：

theme(plot.margin = margin(1,0,0,0, unit = "cm"),
    legend.key.width= unit(4, 'cm'))+

【讨论】：