Plotting multiple bar plots on same y-axis but each on separate x-axis in ggplot2 for count data

Question

I have some count variables against which I want to make bar-plots on the same y-axis but I have no grouping variable. Something like the following plot

B <- 25

iter_M1  
[1] 5 13 14 11  7  8 10 14 10  5  7 13 10 12  4  5  9  6  5 12  8  8  7 11  9 

max_M1 <- max(iter_M1)

count_M1 <- integer(max_M1) 
for(i in 1:max_M1)
 {  
    for(j in 1:B)
     {       
        if(iter_M1[j] == i)  
        count_M1[i] = count_M1[i] +1      
     }  
 }  

 count_M1 
 [1] 0 0 0 1 4 1 3 3 2 3 2 2 2 2  

 df <- data.frame(x = 1:max_M1, y = count_M1)  
 p_M1 <-ggplot(data=df, aes(x=x, y=y)) +  geom_bar(stat="identity")  
 p_M1

This results in a plot like this

and another similar variable

iter_M2  
[1] 3 1 3 2 6 3 4 4 3 7 4 2 2 3 4 3 4 4 1 3 7 3 2 4 2

max_M2 <- max( iter_M2) 
count_M2  <- integer(max_M2) 
for(i in 1:max_M2)
{   
 for(j in 1:B)
 {          
 if(iter_M2[j] == i)    
 count_M2[i] = count_M2[i] +1   
 }
} 

count_M2
[1] 2 5 8 7 0 1 2 df1 <- data.frame(x1 = 1:max_M2, y1 = count_M2)

p_M2 <-ggplot(data=df1, aes(x=x1, y=y1)) +  
geom_bar(stat="identity") p_M2

which results in a second plot as

and similar variables like these... How can I plot this data side by side. Also the way I'hv generated data currently, there is no common y-axis for all x-axis. Are there some suggestion to generate such a plot or dataset in other format to achive the requried plot.

Answer 1

As suggested in the comments, making a factor (class) is the easiest way, allowing you to facet the plot.

But you seem explicitly just to want to have the same y-axis. This is achievable with the scale limits. For example, generate a vector with the limits based on max and then use this in your plots.

ylimits <- c(0, max(c(count_M1, count_M2)))

p_M1 + ylim(ylimits)

p_M2 + ylim(ylimits)