r - how do you order Months in ggplot

Question

I have this data frame called yy:

structure(list(Time = structure(c(1209096000, 1238731200, 1272600000, 
1301666400, 1335794400, 1364835600, 1218772800, 1250222400, 1280808000, 
1314028800, 1346421600, 1377835200, 1229317200, 1262235600, 1291352400, 
1324047600, 1355497200, 1385960400, 1204261200, 1235710800, 1265950800, 
1298646000, 1328281200, 1360940400, 1199250000, 1232082000, 1263186000, 
1295017200, 1326466800, 1357149600), class = c("POSIXct", "POSIXt"
), tzone = ""), Peak_Logons = c(472452L, 398061L, 655849L, 881689L, 
873720L, 1278295L, 340464L, 520943L, 1995150L, 883184L, 931721L, 
1098553L, 405193L, 638301L, 734635L, 1254951L, 962391L, 1126432L, 
316200L, 477407L, 674884L, 812793L, 898550L, 1541478L, 291564L, 
394967L, 902076L, 916832L, 878264L, 918102L), Year = c("2008", 
"2009", "2010", "2011", "2012", "2013", "2008", "2009", "2010", 
"2011", "2012", "2013", "2008", "2009", "2010", "2011", "2012", 
"2013", "2008", "2009", "2010", "2011", "2012", "2013", "2008", 
"2009", "2010", "2011", "2012", "2013"), Month = c("April", "April", 
"April", "April", "April", "April", "August", "August", "August", 
"August", "August", "August", "December", "December", "December", 
"December", "December", "December", "February", "February", "February", 
"February", "February", "February", "January", "January", "January", 
"January", "January", "January")), .Names = c("Time", "Peak_Logons", 
"Year", "Month"), row.names = c(35479L, 30535L, 23645L, 15248L, 
49696L, 8077L, 24651L, 13098L, 20204L, 47450L, 41228L, 20740L, 
28049L, 9739L, 2636L, 50230L, 43746L, 3435L, 38091L, 28351L, 
7382L, 3343L, 47824L, 45481L, 23951L, 29664L, 10024L, 4545L, 
38808L, 44205L), class = "data.frame")

What I would like to do is create a heat map, Year on the y-axis and Month on the x-axis.

I am doing this:

 ggplot(yy ,aes(Month, Year, fill=Peak_Logons)) + 
   geom_tile() + 
   theme_bw() + 
   guides(fill = guide_legend(keywidth = 5, keyheight = 1)) + 
   theme(axis.text.x = element_text(size=10, angle=45, hjust=1))

This kinda works but Months on x-axis are not order from January, February, March, April ... December.

They are order aphabetically from April, August etc.

1. How would I order the x-axis from January to December?
2. Is there a way to change the default colors, it looks like it is using blue shades?
3. Can I isert text the the geom_tiles? I would like to insert Time and Peak_Logons inside the tiles.

I would really appreciate any insight.

Answer 1

• Use reorder to arrange your axis labels. I create a new column with month index.
• geom_text to add text. Maybe you should play with text size.
• scale_fill_gradientn to change fill color. See also scale_fill_gradientn

dat.m <- data.frame(Month=months(seq(as.Date("2000/1/1"), 
              by = "month", length.out = 12)),month.id = 1:12)

yy <- merge(yy,dat.m)
library(ggplot2)
ggplot(yy ,aes(reorder(Month,month.id), Year, fill=Peak_Logons)) +
    geom_tile() + 
    theme_bw() + 
    guides(fill = guide_legend(keywidth = 5, keyheight = 1)) + 
    theme(axis.text.x = element_text(size=10, angle=45, hjust=1)) +
    geom_text(aes(label=paste(Peak_Logons,format(Time,"%H"),sep='-'))) +
    scale_fill_gradient(low = "yellow",  high = "red")