[英]How to change y-axis to log-scale?
This question is related to a previous post .这个问题与之前的帖子有关。
Say I have this set of data test
:说我有这组数据
test
:
a b c
1 a x NA
2 b x 5.1e-03
3 c x 2.0e-01
4 d x 6.7e-05
5 e x NA
6 f y 6.2e-05
7 g y 1.0e-02
8 h y 2.5e-03
9 i y 9.8e-02
10 j y 8.7e-04
> dput(test)
structure(list(a = structure(1:10, .Label = c("a", "b", "c",
"d", "e", "f", "g", "h", "i", "j"), class = "factor"), b = structure(c(1L,
1L, 1L, 1L, 1L, 2L, 2L, 2L, 2L, 2L), .Label = c("x", "y"), class = "factor"),
c = c(NA, 0.0051, 0.2, 6.7e-05, NA, 6.2e-05, 0.01, 0.0025,
0.098, 0.00087)), .Names = c("a", "b", "c"), row.names = c(NA,
-10L), class = "data.frame")
Plotting it regularly with ggplot will give this graph:用 ggplot 定期绘制它会得到这个图:
> ggplot(test, aes(fill=a,y=c,x=b)) +
geom_bar(position="dodge",stat="identity")
How do I set the y-axis as log scale (eg, 0, 10 -6 , 10 -5 , 10 -4 ... 10 0 ) so that the height of the bars won't be too far apart without directly log-transforming the data?如何将 y 轴设置为对数刻度(例如 0, 10 -6 , 10 -5 , 10 -4 ... 10 0 ),以便在没有直接记录的情况下,条形的高度不会相距太远- 转换数据? Also, how do I accomplish this in such a way that it still shows the
NA
values as zeroes in the graph?另外,我如何以这样的方式实现这一点,它仍然在图中将
NA
值显示为零?
I also tried the scale_y_log10()
function but the bars go from top to bottom.我也尝试了
scale_y_log10()
函数,但条形图从上到下。 I would like them not to be that way.我希望他们不要那样。
Thank you!谢谢!
You can use geom_segment
instead rather than geom_bar
to specify you want a bar from 0
to test$c
value.您可以使用
geom_segment
而不是geom_bar
来指定您想要一个从0
到test$c
值的条。 A warning will be issued as we are still using scale_y_log10()
.由于我们仍在使用
scale_y_log10()
因此将发出警告。
We need to create a segment from each test$a
so aes(x=a, xend=a)
, and use facet_wrap
to separate test$b
x
and y
instead.我们需要从每个
test$a
创建一个段aes(x=a, xend=a)
,并使用facet_wrap
来分隔test$b
x
和y
。
gg <- ggplot(test) +
geom_segment(aes(colour=a, y=0, yend=c, x=a, xend=a), size=10) +
scale_y_log10() + facet_wrap(~b, scales="free_x") +
ylab("log10 value") + xlab("")
gg
I am not a fan of replacing NA
with 0
, a missing value is not 0
.我不喜欢用
0
替换NA
,缺失值不是0
。 Rather just label NA
.而只是标记
NA
。
test$c_label <- test$c
test$c_label[is.na(test$c)] <- "NA"
gg + geom_label(data=subset(test, is.na(test$c)), aes(x=a, y=0.00001, label=c_label), size=5)
While this might be a work-around, I complete agree with @dww's comment - "You should not use a log scale with bar plots. The base at log(0) is impossible to plot. Choice of a different base value is arbitrary and can be used to make the bars look as similar or as different as you wish depending on the value chosen. This is a form of misleading graph. Use a dot plot, or something else instead if you really need log scale."虽然这可能是一种变通方法,但我完全同意 @dww 的评论——“你不应该在条形图中使用对数刻度。无法绘制 log(0) 处的基数。选择不同的基值是任意的,并且可用于根据选择的值使条形看起来像您希望的那样相似或不同。这是一种误导性图表。如果您确实需要对数刻度,请使用点图或其他东西。”
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