[英]Adding italicised r with correlation coefficient to a scatter plot chart in ggplot
我嘗試使用下面的代碼生成,將有放置在情節斜體為r的相關系數簡單的散點圖。
data(mtcars)
# Load required libraries
require(ggplot2) # To derive the graphs
require(ggthemes) # To apply ggplot themes to the chart
require(scales) # For pretty breaks
# Function to generate correlation coefficient for the charts
corr_eqn <- function(x,y, digits = 2) {
corr_coef <- round(cor(x, y), digits = digits)
corr_coef <- expression(paste(italic(r)," = ", corr_coef))
return(corr_coef)
}
# Provide a scatter plot for income and health deprivation
ggplot(mtcars, aes(x = drat, y = wt)) +
geom_point(shape = 19, size = 2, aes(colour = as.factor(cyl))) +
geom_smooth(colour = "red", fill = "lightgreen", method = 'lm') +
ggtitle("Example") +
xlab("drat") +
ylab("wt") +
scale_colour_tableau("tableau10") +
geom_text(x = 3, y = 3,
label = corr_eqn(mtcars$drat,
mtcars$wt), parse = TRUE) +
theme(legend.key = element_blank(),
legend.background = element_rect(colour = 'black'),
legend.position = "bottom",
legend.title = element_blank(),
plot.title = element_text(lineheight = .8, face = "bold", vjust = 1),
axis.text.x = element_text(size = 11, vjust = 0.5,
hjust = 1, colour = 'black'),
axis.text.y = element_text(size = 11, colour = 'black'),
axis.title = element_text(size = 10, face = 'bold'),
axis.line = element_line(colour = "black"),
plot.background = element_rect(colour = 'black', size = 1),
panel.background = element_blank())
代碼停止了?
在控制台中標記。 使用以下行運行代碼:
# geom_text(x = 3, y = 3,
# label = corr_eqn(mtcars$drat, mtcars$wt), parse = TRUE) +
評論,生成以下圖表:
我猜我生成格式為r = 0.7的方程式的函數不起作用,我該如何解決?
如您所料,您只需要調整您的功能。 您可以使用此答案中所示的 substitute
,但您也可以在此處使用paste
。
corr_eqn <- function(x,y, digits = 2) {
corr_coef <- round(cor(x, y), digits = digits)
paste("italic(r) == ", corr_coef)
}
請注意,如果您將as.character
添加到原始函數返回的內容中,則會解析。 但是,結果將使用corr_coef
作為字符串而不是您想要的實際相關系數。
我還應該補充一點,如果不將標簽和坐標放入新的data.frame中, geom_text
會導致分辨率不佳。
labels = data.frame(x = 3, y = 3, label = corr_eqn(mtcars$drat, mtcars$wt))
然后使用data
參數和aes
for geom_text
:
geom_text(data = labels, aes(x = x, y = y,
label = label), parse = TRUE)
請參閱使用geom = "text"
annotate
作為避免新data.frame的另一個選項。
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