ggplot2 binwidth not responding in facet_wrap histogram plot

Question

Would appreciate any thoughts on how to make my code or binwidth behave. My dataset contains timestamped data points collected every few hours "4", and daily "24". I am trying to plot the 4 hour stacked histograms on the left and the 24 hour stacked histograms on the right. Therefore, I want the binwidth on the right to be 6x wider than the left binwidth. But everything I've tried with binwidth has not worked. The x axis data, data3$dts appears to be continuous and not discrete but maybe I'm not doing that right.

Important note about the data: Data that gets graphed on the right side, the hours=24 data, has a dts value that is always an integer. Data on the left, the hours=4 data, has non-integer dts values.

             "dts"  "Yes" "No" "Maybe" "hours"  "days"
"258"   15627.668   8       0   1       4   "7 Days"
"259"   15627.832   13      11  18      4   "7 Days"
"260"   15628       34      47  89      4   "7 Days"
"261"   15628       37      47  90      24  "7 Days"
"262"   15628.168   3       0   1       4   "7 Days"
"40"    15571       345     419 674     24  "90 Days"
"41"    15571.5     91      145 130     4   "90 Days"
"42"    15571.668   158     149 284     4   "90 Days"
"43"    15571.832   96      125 260     4   "90 Days"
"44"    15572       55      33  137     4   "90 Days"
"45"    15572       1050    1119 2660   24  "90 Days"

Code with data pulled from pastebin:

library (ggplot2)
library (scales)
library(grid)
library(gridExtra)

color3 <- c("mediumspringgreen","red","grey44")
titles.days <-  c( "7 Days", "90 Days") 
names.facetby <- c ("dts", "hours", "days")

data3 <- read.table ("http://pastebin.com/download.php?i=wUQQUXP4", header=TRUE)
data3.melt <- melt (data3 , id = names.facetby )   
data3.melt$days <- factor (data3.melt$days, levels = titles.days)   #  put the factor in the right order, so the graphs are in the right order

 a <- ggplot     ( data3.melt 
        , aes (       x =  dts  #as.Date( dts , date1970) 
                , y =  value 
                , fill = variable)) +
        opts (axis.text.x=theme_text(angle=0, hjust=1)) +
        scale_fill_manual(values = color3) +
        scale_x_date(labels = date_format("%m/%d\n    %a") ) +
        geom_histogram (stat = "identity", position = "stack", binwidth=6.2) +  
        facet_wrap( days ~ hours, ncol=2, scales="free")            

print(a)        

Current results, showing the right sided graphs with binwidth way too narrow:

Answer 1

@justin's link to Hadley Wickham's post has the answer, which is to plot left and right graphs in different layers.

Updated code that plots correctly with 2 new geom_histogram lines inside the ggplot:

library (ggplot2) library (scales) library(grid) library(gridExtra)

color3 <- c("mediumspringgreen","red","grey44")
titles.days <-  c( "7 Days", "90 Days") 
names.facetby <- c ("dts", "hours", "days")

data3 <- read.table ("http://pastebin.com/download.php?i=wUQQUXP4", header=TRUE)
data3.melt <- melt (data3 , id = names.facetby )   
data3.melt$days <- factor (data3.melt$days, levels = titles.days)   #  put the factor in the right order, so the graphs are in the right order



 a <- ggplot     ( data3.melt 
        , aes (       x =  dts  #as.Date( dts , date1970) 
                , y =  value 
                , fill = variable)) +
        opts (axis.text.x=theme_text(angle=0, hjust=1)) +
        scale_fill_manual(values = color3) +
        scale_x_date(labels = date_format("%m/%d\n%a") ) +

    # bad idea, good ideas follow   geom_histogram (stat = "identity", position = "stack", binwidth=6.2) +  #, breaks = breaks.x
        geom_histogram (data =  subset(data3.melt, hours == 4),  stat = "identity", position = "stack", binwidth=0.3) + #, breaks = breaks.x
        geom_histogram (data =  subset(data3.melt, hours == 24),  stat = "identity", position = "stack", binwidth=0.9) +    #, breaks = breaks.x

        facet_wrap( days ~ hours, ncol=2, scales="free")            

print(a)        # plot the thing

Corrected graph: