How can I interpolate the value of points placed on a timeline?-CodePudding

I want to create an interpolated plot of the concentration of 'x' over time at different locations. If possible, I would like to interpolate the points horizontally (i.e. over time) in a way that I get smooth color-changing horizontal lines for each sample.

df<-data.frame(Concentration = rnorm(30), Position = rep(c(0, 1), 15), Sample = rep(c("A", "B"), 15), Date = seq.Date(as.Date("2020-01-01"), as.Date("2020-01-30"), "days"))

df %>% 
  ggplot(aes(x = Date, y = Position))  
    geom_hline(yintercept = c(0,1),
              size = 0.3)  
    geom_tile(aes(fill = Concentration),
               interpolate = T)  
    xlab("Day") 
    ylab("Sample")

I would appreciate any suggestions. Lee

CodePudding user response：

Not sure I fully understand the question, but here is one possible solution to what I think you are asking.

library(tidyverse)
library(gt)

df <-
  data.frame(Concentration = rnorm(30),
             Sample = rep(c("A", "B"), 15),
             Date = seq.Date(as.Date("2020-01-01"), 
                             as.Date("2020-01-30"), "days"))

interpolated_df <- 
  df %>% 
  arrange(Sample) %>% 
  complete(Sample, Date) %>% 
  ## interpolated is average of value right before and right after
  mutate(Interpolations = (lead(Concentration)   
                       lag(Concentration))/2 ) %>% 
  mutate(Final = coalesce(Concentration, Interpolations)) 
  
## plot
interpolated_df %>% 
ggplot(aes(x = Date, y = Sample))  
  geom_tile(aes(fill = Final))  
  xlab("Day") 
  ylab("Sample")

^{Created on 2021-10-25 by the reprex package (v2.0.1)}

CodePudding user response：

That's exactly what ggforce::geom_link was made for.

library(tidyverse)
library(ggforce)

set.seed(42)
df <- data.frame(Concentration = rnorm(30), Position = rep(c(0, 1), 15), Sample = rep(c("A", "B"), 15), Date = seq.Date(as.Date("2020-01-01"), as.Date("2020-01-30"), "days"))

df %>%
  ggplot(aes(x = Date, y = Position))  
  geom_link2(aes(group = Position, color = Concentration), size = 10)  
  labs(x = "Day", y = "Sample")

^{Created on 2021-10-25 by the reprex package (v2.0.1)}