[R] ggplot2: Plot multiple lines using stacked data.

[Sorkin, John]

I am trying to use ggplot2 to create a figure with multiple lines, one line for each value of the variable Day. Each group of data for Day requires seven lines. The dataframe has data for 4 days and thus 4*7=28 lines.

I can create a plot, but the plot only contains dots. The dots for each day should be connected each day's data by a different line. There should be a total of four lines on the graph 

mydata <-structure(list(Day = c("25", "25", "25", "25", "25", "25", "25", 
                       "26", "26", "26", "26", "26", "26", "26", "27", "27", "27", "27", 
                       "27", "27", "27", "28", "28", "28", "28", "28", "28", "28"), 
               AQIGroup = structure(c(1L, 2L, 3L, 4L, 5L, 6L, 7L, 1L, 2L, 
                        3L, 4L, 5L, 6L, 7L, 1L, 2L, 3L, 4L, 5L, 6L, 7L, 1L, 2L, 3L, 
                        4L, 5L, 6L, 7L), levels = c("Good", "Moderate", "UnForSome", 
                        "UH", "VUH", "Haz1", "Hax2"), class = "factor"), Freq = c(98.05, 
                         0.37, 0.27, 0.17, 0.26, 0.5, 0.38, 93.34, 4.34, 0.75, 0.42, 
                         0.44, 0.44, 0.27, 89.57, 7.8, 0.98, 0.38, 0.5, 0.52, 0.25, 
                        80.43, 13.33, 3.85, 0.76, 0.86, 0.28, 0.49)), class = "data.frame", row.names = c(NA, -28L))

# You can see that the data are stacked, one day on top of the next.
# Each day requires seven lines.
mydata

# Load ggplot2
if(!require(ggplot2)) {install.packages(ggplot2)}
library(ggplot2)
# Create a graph, with multiple lines, one line for each value of Day.
ggplot(mydata, aes(AQIGroup,Freq,color=Day)) +
  geom_point()+
  geom_line(aes(AQIGroup,Freq))

Thank you,
John


John David Sorkin M.D., Ph.D.
Professor of Medicine, University of Maryland School of Medicine;
Associate Director for Biostatistics and Informatics, Baltimore VA Medical Center Geriatrics Research, Education, and Clinical Center; 
PI Biostatistics and Informatics Core, University of Maryland School of Medicine Claude D. Pepper Older Americans Independence Center;
Senior Statistician University of Maryland Center for Vascular Research;

Division of Gerontology and Paliative Care,
10 North Greene Street
GRECC (BT/18/GR)
Baltimore, MD 21201-1524
Cell phone 443-418-5382