I'm relatively new to R and I'm struggling to figure out a way to get a set of plots with different y values. Below is a simplified version of the dataset I'm working on.

Cell	x	y1	y2	y3	y4
A	1	0.5	0.7	0.9	1.1
A	2	0.6	0.8	1.0	1.2
A	3	0.7	0.9	1.1	1.3
B	1	0.5	2.9	4.0	3.1
B	2	0.6	3.0	4.1	3.2
B	3	0.7	3.1	4.2	3.3

As it stands now, what I have is the code below

ggplot(ETO2, aes(x = x, y = y1)  
geom_line()  
facet_wrap(~Cell) 

Is there a simple way to plot different y-values per facet? For example I would want data with Cell=A to plot y1 over x and for data with Cell=B i'd want it to plot y3 over x. Preferably i would like to see the plots as one output. Note that in my actual data sets, there are a lot more cell lines, and it would also be nice to easily switch the columns for the y-values.

Thank you so much, and I hope I explained my intention as clear as possible. If not, please feel free to ask more.

CodePudding user response：

In general, "no", but you can create a new variable that takes from y1 or y3 depending on the Cell. If it's just two values, then ifelse will suffice,

ETO2$y0 <- ifelse(ETO2$Cell == "A", ETO2$y1, ETO2$y3)

If there are more, though, you may prefer dplyr::case_when or data.table::fcase.

From here, just choose the new variable y0 instead:

ggplot(ETO2, aes(x = x, y = y0))  
 geom_line()  
 facet_wrap(~Cell) 

CodePudding user response：

Another solution would be to produce two plots by filtering ET02 on values of column Cell, then joining to have a single output. You can easily switch for various columns as y axis in this way

library(ggplot2)
library(tidyverse)
library(patchwork) # package for joining ggplot2 plots in different ways

ETO2 %>%  
  filter(Cell == "A") %>% # select only rows with "A" value in Cell
  ggplot(., aes(x = x, y = y1))   # plot over desired y
           geom_line() -> p1

ETO2 %>%  
  filter(Cell == "B") %>% # select only rows with "B" value in Cell
  ggplot(., aes(x = x, y = y3))   # plot over desired y
  geom_line() -> p2

p1   p2 # side by side
p1 / p2 # top and bottom

In case you would like to have the same ranges of y axis with different values, you can set ylim()

p1   ylim(0,5) -> p1_lim
p2   ylim(0,5) -> p2_lim

p1_lim   p2_lim 

CodePudding user response：

Create a dictionary dict specifying which y column to plot in which cell, merge it with ETO2, create a new y variable and plot. If any cells are not to be associated with a facet then omit such cells from dict.

library(dplyr)
library(ggplot2)

dict <- data.frame(Cell = c("A", "B"), ycol = c("y1", "y3"))

ETO2 %>%
  inner_join(dict, by = "Cell") %>%
  rowwise %>% 
  mutate(Cell = paste(Cell, ycol, sep = "-"), y = get(ycol)) %>%
  ungroup %>%
  ggplot(aes(x, y))  
    geom_line()  
    facet_wrap(~ Cell)

Note

ETO2 <- structure(list(Cell = c("A", "A", "A", "B", "B", "B"), x = c(1L, 
2L, 3L, 1L, 2L, 3L), y1 = c(0.5, 0.6, 0.7, 0.5, 0.6, 0.7), y2 = c(0.7, 
0.8, 0.9, 2.9, 3, 3.1), y3 = c(0.9, 1, 1.1, 4, 4.1, 4.2), y4 = c(1.1, 
1.2, 1.3, 3.1, 3.2, 3.3)), class = "data.frame", row.names = c(NA, 
-6L))