Isssue with creating multiple ggplots using for loop R

Question

I am trying to create 6 ggplot objects graphing the same graph but labeled differently, the labeling being stored in object{1:6}

ggrun<- c(1,2,3,4,5,6) 
for(i in ggrun) {assign(paste0("ggplot_", i), 
(ggplot(DF1, aes(x=X, y=Y, color=as.factor(get(paste0("object", i))[["cluster"]]))) + geom_point(fill = NA, size=1, alpha=0.6)))}

But this produced 6 identical objects, with the proper {1:6} names, but all with the same value of object6.

I checked my for loop too,

for(i in ggrun) {print(table(get(paste0("hdbscan_object", ggrun[i]))[["cluster"]]))}

and it spat out 6 distinct tables.

further, to make sure it was not my plotting command:

grid.arrange(grobs = g, ncol(3), nrow(2), top="Title of Graphs")

I manually assigned each item in the list object, e.g.:

g[[5]] = ggplot(DF1, aes(x=PC1, y=PC4, color=as.factor(get(paste0("object", "5"))[["cluster"]])))  
+ geom_point(fill = NA, size=1, alpha=0.6)

and it ran correctly.

Try to initialize a list of length i.e. g <- vector('list', length(ggrun)) — akrun
– akrun, Commented Jan 6, 2021 at 23:38
@akrun I tried to initialize a list of length ggrun, g <- vector('list', length(ggrun)), then I ran g[[i]] = ggplot(DF1, aes(x=PC1, y=PC4, color=as.factor(get(paste0("object", ggrun[i]))[["cluster"]]))) + geom_point(fill = NA, size=1, alpha=0.6) and the same thing happened, only [[6]] contained information, corresponding to object6 — Sky Scraper
– Sky Scraper, Commented Jan 6, 2021 at 23:44
Please check what the value of object1[["cluster"]] and object6[["cluster"]] — akrun
– akrun, Commented Jan 6, 2021 at 23:45
@akrun They contain different values, if i put them into an object they are Values objects with typeof() double and class() numeric. Printing each of the contents, they are a series of numbers corresponding to the cluster identity 1 1 1 1 1 2 2 4 4 4 4 4 4 — Sky Scraper
– Sky Scraper, Commented Jan 6, 2021 at 23:50
IN your code example, i didn't see the for loop in the second code block i.e. g <- vector('list', length(ggrun)); for(i in ggrun) g[[i]] <- ggplot(DF1, aes(x=PC1, y=PC4, color=as.factor(get(paste0("object", ggrun[i]))[["cluster"]]))) + geom_point(fill = NA, size=1, alpha=0.6) — akrun
– akrun, Commented Jan 6, 2021 at 23:52

Daniel V · Accepted Answer · 2021-01-07 00:46:50Z

1

ggplot works a bit weirdly with for loops as many of the internal operations seem to rely on pointers rather than actually storing the values. To work around this, you will often have to create a new environment for them to protect from the value that the pointer points at from being changed.

You can try storing the values in a list and using the lapply function:

g <- lapply(1:6, 
            function (x){
                ggplot(DF1, aes(x=PC1, y=PC4, 
                       color=as.factor(get(paste0("object", x))[["cluster"]]))) + 
                    geom_point(fill = NA, size=1, alpha=0.6)
            }
     )

answered Jan 7, 2021 at 0:46

Daniel V

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Ronak Shah · Accepted Answer · 2021-01-07 05:33:20Z

1

Here's another way using mget :

library(ggplot2)

lapply(mget(paste0("object", 1:6)), function(x) {
  ggplot(DF1, aes(x=PC1, y=PC4, 
                  color= factor(x[["cluster"]]))) + 
    geom_point(fill = NA, size=1, alpha=0.6)
}) -> list_plots

list_plots

answered Jan 7, 2021 at 5:33

Ronak Shah

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