plotting with empty column

[xinxi813]

hi everyone, I would like to make a plot with an empty column in it. The reason that I still want to include this column in the R code is, I have multiple groups, with this column empty for some groups, but not for others. And the data of these groups are not available at the same time. I would like to make an R code for all these groups so that I do not need to change the code every time I obtain the data from a new group.

Here is an replicable example for one group with a column of missing data.

library(ggplot2) 

mtcars$disp=NA

ggplot(mtcars)+
  geom_line(data=mtcars[!is.na(mtcars$mpg),],aes(y=mpg,x=as.factor(carb),color='c1'))+geom_point(aes(y=mpg,x=as.factor(carb)))+
  geom_line(data=mtcars[!is.na(mtcars$disp),],aes(y=disp,x=as.factor(carb),color='c2'))+geom_point(aes(y=disp,x=as.factor(carb)))+
  geom_line(data=mtcars[!is.na(mtcars$qsec),],aes(y=qsec,x=as.factor(carb),color='c3'))+geom_point(aes(y=qsec,x=as.factor(carb)))+
  scale_color_manual(values=c('c1'='red','c2'='yellow','c3'='blue'),labels=c('mpg','disp','qsec'))+
  labs(x='carb',y='values',title='mtcars')

The error message is:

Aesthetics must be either length 1 or the same as the data (1): x and y
Run `rlang::last_error()` to see where the error occurred.

Is there any way I can still get the plot of the mpg and qsec (in one plot), even thought disp is fully missing?

Thank you very much.

[DavoWW]

Hi @xinxi813,
It looks like you are trying to plot a single graph with several different Y axes; this is generally a bad idea and is difficult to achieve. Another option is to do a "pairs plot" and exclude at the beginning any columns of the data frame containing missing values. This approach produces a single graph that has multiple panels (which can be customized to your liking):

suppressPackageStartupMessages(library(tidyverse))
library(GGally)
#> Registered S3 method overwritten by 'GGally':
#>   method from   
#>   +.gg   ggplot2

mtcars$disp=NA  # Put missing values in one column
head(mtcars)
#>                    mpg cyl disp  hp drat    wt  qsec vs am gear carb
#> Mazda RX4         21.0   6   NA 110 3.90 2.620 16.46  0  1    4    4
#> Mazda RX4 Wag     21.0   6   NA 110 3.90 2.875 17.02  0  1    4    4
#> Datsun 710        22.8   4   NA  93 3.85 2.320 18.61  1  1    4    1
#> Hornet 4 Drive    21.4   6   NA 110 3.08 3.215 19.44  1  0    3    1
#> Hornet Sportabout 18.7   8   NA 175 3.15 3.440 17.02  0  0    3    2
#> Valiant           18.1   6   NA 105 2.76 3.460 20.22  1  0    3    1

# Columns we are interested in (although some MAY have missing values)
response <- c("mpg","disp","qsec","wt")
explanatory <- "carb"

# Plot the graphs
mtcars %>% 
  select(matches(c(response, explanatory))) %>% 
  select_if(~ !any(is.na(.))) %>%   # Ignore any columns with NAs
  ggpairs(lower=list(continuous="smooth"))

# Or, leave the missing values in and see where they are 
mtcars %>% 
  select(matches(c(response, explanatory))) %>% 
  #select_if(~ !any(is.na(.))) %>%   # Ignore any columns with NAs
  ggpairs(lower=list(continuous="smooth"))

^{Created on 2021-07-25 by the reprex package (v2.0.0)}

[xinxi813]

hi @DavoWW ,

Thank you very much for the response.

I finally got the idea of ggpairs(), I think the three panels on the button line are what I need. But how to make the carb as the X-axis? The output plot matrix is quite complicated for presentation, is it possible to get rid of other panels and keep the three with mpg, qsec, and wt as Y-axis?