guide_legend和ggplot2，格式为行 [英] guide_legend and ggplot2, format nrow

问题描述

我正在尝试在ggplot上格式化一个超长的图例，以使最大编号不存在.行.我已经阅读了所有可以找到的文档，尤其是: http://docs.ggplot2.org/0.9.3.1/guide_legend.html ，但由于某些原因，图例将无法格式化.

I am trying to format an over-long legend on a ggplot so that there is a maximum no. of rows. I've read all the documentation that I could find, especially this: http://docs.ggplot2.org/0.9.3.1/guide_legend.html but for some reason, the legend will not format.

我在下面使用地震数据集提供了可重现的样本，并将列测站转换为字符，以便它们分别绘制(否则，它们似乎作为组绘制).

I've given a reproducible sample below using the quakes dataset, and converted the column stations to character so that they plot individually (otherwise, they seem to plot as groups).

plotquakes <- function(magreq) {
    library(ggplot2)
    magdata <- subset(quakes, mag > magreq)
    magdata$stations <- as.character(magdata$stations)
    g <- ggplot(magdata, aes (x = lat, y = long))
    g + geom_point(aes(alpha = stations), fill = "black", pch=21, size = 6) + 
    labs(x = "Latitude", y = "Longitude") + 
    geom_vline(xintercept = 0, col = "red") + 
    geom_hline(yintercept = 0, col = "red") +
    guides(col = guide_legend(nrow = 16))
}

plotquakes(5)

我得到的是这样的:

而我想在图例中每列最多包含16个数据字段.

whereas I would like to have a maximum of 16 data fields per column in the legend.

推荐答案

您正在更改错误的指南.

You are changing the wrong guide.

plotquakes <- function(magreq) {
  library(ggplot2)
  magdata <- subset(quakes, mag > magreq)
  magdata$stations <- as.character(magdata$stations)
  g <- ggplot(magdata, aes (x = lat, y = long))
  g + geom_point(aes(alpha = stations), fill = "black", pch=21, size = 6) + 
    labs(x = "Latitude", y = "Longitude") + 
    geom_vline(xintercept = 0, col = "red") + 
    geom_hline(yintercept = 0, col = "red") +
    guides(alpha = guide_legend(nrow = 16)) #note it's alpha not col
}

plotquakes(5)

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