为什么geom_histogram从负bin下限开始，即使所有值都大于>0? [英] Why does geom_histogram start at negative bin lower limit even though all values are > 0?

问题描述

我正在尝试H.Wickham在R book中的钻石数据集.在x =克拉的钻石的默认geom_histogram中，binwidth是0.5，但是bin 1从-0.25开始，即使克拉的最低值为0.2.为什么会这样呢?附加图片和上下文代码.谁能帮忙解释一下.谢谢.

I'm trying out the diamonds dataset in R book by H.Wickham. In the default geom_histogram for diamonds where x = carat, the binwidth is 0.5 but bin 1 starts at -0.25 even though the lowest value for carat is 0.2. Why would this be so? Attaching pic and code for context. Can anyone help explain. Thanks.

##geom_histogram
geom_histogram(mapping=aes(x = carat),binwidth = 0.5)

summary(diamonds)
##dplyr to get count of cut[![enter image description here][1]][1]
diamonds %>%
count(cut_width(carat,0.5))

推荐答案

有帮助吗?

在p1中，第一个容器位于0的中心.但是您希望容器的左侧从0-p2开始.因此，您必须告诉ggplot转移垃圾箱.您可以使用文档中讨论的 boundary 或 center 自变量来完成此操作.

In p1 the first bin is centered on 0. But you want the left hand side of the bin to start with 0 - p2. So you have to tell ggplot to shift the bins. You can do this using a boundary or center argument which are discussed in the documentation.

library(ggplot2)
library(patchwork)

##geom_histogram

p1 <- 
  ggplot(diamonds)+
  geom_histogram(mapping=aes(x = carat), binwidth = 0.5)+
  ggtitle("p1 bars centred on bin boundaries")


p2 <- 
  ggplot(diamonds)+
  geom_histogram(mapping=aes(x = carat), binwidth = 0.5, boundary = 0)+
  ggtitle("p2 bars between bin boundaries")




p1+p2

^{由 reprex软件包(v0.3.0)创建于2020-05-25 sup>}

^{Created on 2020-05-25 by the reprex package (v0.3.0)}

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