Save ggplot in loop with R - r

Question

I have a dataset with numeric and factor variables. I want to do one page with numeric and other with factor var. First of all, i select factor var with his index.
My df is IRIS dataset.
df<-iris
df$y<-sample(0:1,nrow(iris),replace=TRUE)
fact<-colnames(df)[sapply(df,is.factor)]
index_fact<-which(names(df)%in%fact)
Then i calculate rest of it (numerics)
nm<-ncol(df)-length(fact)
Next step is create loop
i_F=1
i_N=1
list_plotN<- list()
list_plotF<- list()
for (i in 1:length(df)){
plot <- ggplot(df,aes(x=df[,i],color=y,fill=y))+xlab(names(df)[i])
if (is.factor(df[,i])){
p_factor<-plot+geom_bar()
list_plotF[[i_F]]<-p_factor
i_F=i_F+1
}else{
p_numeric <- plot+geom_histogram()
list_plotN[[i_N]]<-p_numeric
i_N=i_N+1
}
}
When i see list_plotF and list_plot_N,it didn't well. It always have same vars. i don't know what i'm doing wrong.
thanks!!!

Answer 1

I don't really follow your for loop code all that well. But from what I see it seems to be saving the last plot in every loop you make. I've reconstructed what I think you need using lapply. I generally prefer lapply to for loops whenever I can.
Lapply takes a list of values and a function and applies that function to every value. you can define your function separately like I have so everything looks cleaner. Then you just mention the function in the lapply command.
In our case the list is a list of columns from your dataframe df. The function it applies first creates our base plot. Then it does a quick check to see if the column it is looking at is a factor.. If it's a factor it creates a bar graph, else it creates a histogram.
histOrBar <- function(var) {
basePlot <- ggplot(df, aes_string(var))
if ( is.factor(df[[var]]) ) {
basePlot + geom_bar()
} else {
basePlot + geom_histogram()
}
}
loDFs <- lapply(colnames(df), histOrBar)

Answer 2

Consider passing column names with aes_string to better align x with df:
for (i in 1:length(df)){
plot <- ggplot(df, aes_string(x=names(df)[i], color="y", fill="y")) +
xlab(names(df)[i])
...
}
To demonstrate the problem using aes() and solution using aes_string() in OP's context, consider the following random data frame with columns of different data types: factor, char, int, num, bool, date.
Data
library(ggplot2)
set.seed(1152019)
alpha <- c(LETTERS, letters, c(0:9))
data_tools <- c("sas", "stata", "spss", "python", "r", "julia")
random_df <- data.frame(
group = sample(data_tools, 500, replace=TRUE),
int = as.numeric(sample(1:15, 500, replace=TRUE)),
num = rnorm(500),
char = replicate(500, paste(sample(LETTERS[1:2], 3, replace=TRUE), collapse="")),
bool = as.numeric(sample(c(TRUE, FALSE), 500, replace=TRUE)),
date = as.Date(sample(as.integer(as.Date('2019-01-01', origin='1970-01-01')):as.integer(Sys.Date()),
500, replace=TRUE), origin='1970-01-01')
)
Graph
fact <- colnames(random_df)[sapply(random_df,is.factor)]
index_fact <- which(names(random_df) %in% fact)
i_F=1
i_N=1
list_plotN <- list()
list_plotF <- list()
plot <- NULL
for (i in 1:length(random_df)){
# aes() VERSION
#plot <- ggplot(random_df, aes(x=random_df[,i], color=group, fill=group)) +
# xlab(names(random_df)[i])
# aes_string() VERSION
plot <- ggplot(random_df, aes_string(x=names(random_df)[i], color="group", fill="group")) +
xlab(names(random_df)[i])
if (is.factor(random_df[,i])){
p_factor <- plot + geom_bar()
list_plotF[[i_F]] <- p_factor
i_F=i_F+1
}else{
p_numeric <- plot + geom_histogram()
list_plotN[[i_N]] <- p_numeric
i_N=i_N+1
}
}
Problem (using aes() where graph outputs DO NOT change according to type)
Solution (using aes_string() where graphs DO change according to type)