how do you order Months in ggplot - r

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.
How would I order the x-axis from January to December?
Is there a way to change the default colors, it looks like it is using blue shades?
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")

Answer 2

You seem to consider months an ordered factor. You should make it one in R:
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")
Month.ordered <- ordered(Month, month.name)
#[1] April April April April April April August August August August August August December December December December
#[17] December December February February February February February February January January January January January January
#Levels: January < February < March < April < May < June < July < August < September < October < November < December