[英]fix plotly color scale breaks
我已经使用plotly的R接口创建了一个热图,如下所示:
df <- data.frame(date = rep(seq(ymd('2016-09-01'), ymd('2016-09-10'), by='day'), each=2),
period = rep(c('lunch', 'dinner'), times=10),
diff=rnorm(20))
df %>%
plot_ly(x = date,
y = period,
z = abs(diff),
type = "heatmap",
hoverinfo='none',
colors = rev(RColorBrewer::brewer.pal(5, "RdYlGn")),
showscale = F) %>%
add_trace(x = date,
y = period,
text = paste0(round(diff*100), '%'),
mode='text',
hoverinfo='none')
产生这个:
有什么办法可以解决色标的问题吗? 我希望色标的中点为20%,任何超过50%的值在色标的末尾用红色进行着色。
好吧,通常认为热图的颜色会随元素的值而变化,但是您可以根据所需条件将每个元素分为5组中的1组,并相应地分配5种颜色。 然后,该分组将传递到z中。 z应该是数字,而不是因数,因此您可以将分组转换为整数:
# create 5 levels or groups for the diff variable
# choose breaks as desired
diffLevel <- cut(abs(df$diff),
breaks = c(0, 0.0625, .125, .3, .5, Inf))
df %>%
plot_ly(x = date,
y = period,
z = as.integer(diffLevel),
type = "heatmap",
hoverinfo='none',
colors = rev(RColorBrewer::brewer.pal(5, "RdYlGn")),
showscale = F) %>%
add_trace(x = date,
y = period,
text = paste0(round(diff*100), '%'),
mode='text',
hoverinfo='none')
另一种方法是将设置zmax
值到0.5(和zauto = FALSE
)。 这并不一定将色标的中心设置为.2,但效果很好,并设置了0.5的临界值,在该临界值以上的所有部分均为红色。 它还允许您直接传递abs(diff)
:
df %>%
plot_ly(x = date,
y = period,
z = abs(diff),
zauto = FALSE, # set this to FALSE!
zmax = 0.5,
type = "heatmap",
hoverinfo='none',
colors = rev(RColorBrewer::brewer.pal(5, "RdYlGn")),
showscale = F) %>%
add_trace(x = date,
y = period,
text = paste0(round(diff*100), '%'),
mode='text',
hoverinfo='none')
最后一种方法是使用自定义色标。 我发现这很难以righ格式获取colorscale参数。 可能有更好的方法来执行此操作,但是我无法提出任何优雅的方法。
customPalette <- colorRampPalette(c("red", "yellow", "green"))(61)
# I put 30 values between 0 and .2 and and 30 between .2 and 1.
# And so, my palette has 61 colors
customColors <- setNames(
data.frame(breaks = c(seq(0, .2, length.out = 31), seq(.21, 1, length.out = 30)),
colors = as.character(
apply(col2rgb(rev(customPalette)), 2, function(ii)
paste("rgb(", paste(ii, collapse = ","),")", sep = ""))),
stringsAsFactors = FALSE),
NULL)
# not perfect, but it seems to work decently
# initialize a list
colList <- list()
colList[[dim(customColors)[1]]] <- 0
# format custom color list
for(i in seq_len(dim(customColors)[1])) {
colList[[i]] <- c(customColors[i, 1], customColors[i, 2])
}
# set zmax = 0.5 and zauto = FALSE
df %>%
plot_ly(x = date,
y = period,
z = abs(diff),
zauto = FALSE,
zmax = 0.5,
type = "heatmap",
hoverinfo='none',
colorscale = colList,
showscale = F) %>%
add_trace(x = date,
y = period,
text = paste0(round(diff*100), '%'),
mode='text',
hoverinfo='none')
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