# Working with Factors, R Beats Excel
#Script to show how to work with factors. Calculates average GISS anomalies by ENSO phase
## STEP 1: SETUP
library(lattice)
link <-"C:/R_Home/Charts & Graphs Blog/Trend_Chart_w_Change_Pts/GISS_temp_Enso_trend.csv"
 # STEP 2: READ DATA
GISS_Data <- read.csv(link,
             skip = 0, sep = ",", dec=".",
             row.names = NULL, header = TRUE,
             colClasses = c("character","numeric", "character"),
             comment.char="#", col.names = c("GISS_dt", "AnomC", "Enso_p"))
attach(GISS_Data)
### STEP 3: Enso Factor
   Enso_f <- factor(Enso_p, labels=c("LaNina", "Neutral", "ElNino"))
   par(pty="m")
#### Step 4 - Create Yr, Mo, Decade Variables
    GISS_yr.d <- format(as.Date(as.character(GISS_dt),
               format="%Y-%m-%d"),format="%Y")
    GISS_yr_n <- as.numeric(GISS_yr.d)
    GISS_dec <- (as.numeric((GISS_yr_n - 1950) %/% 10) * 10) + 1950
### Step 5 : Plots
# Boxplot to show Anomaly by Enso phase
boxplot(AnomC ~ Enso_f,
     main = "Box & Whisker Plot: GISS Anomaly (1950 - 2008) By ENSO Phase",
     las = 1, pch=16, cex = 1,  col = "lightblue", xlab = "ENSO Phase",
     ylab = expression(paste("GISS Temperature Anomaly - " , degree, "C")),
     ylim =c(-0.4,1.0), border = "blue", boxwex = 0.3)
# Boxplot() to show distribution of temps by factor level
    boxplot(AnomC ~ GISS_dec,
     main = "Box & Whisker Plot: GISS Anomaly (1950 - 2008) By Decade",
     las = 1, pch=16, cex = 1,  col = "lightblue",
     ylab = expression(paste("GISS Temperature Anomaly - " , degree, "C")),
     ylim =c(-0.4,1.0), border = "blue", boxwex = 0.3)
# Lattice plot of Enso p and Decade
   xyplot(AnomC ~ GISS_dec| Enso_f, horizontal = FALSE,
         panel = panel.bwplot,
         main =  "Box Plots: GISS Anomaly (1950 - 2008) By ENSO Phase and Decade",
         xlab = NULL,
         ylab =  expression(paste("GISS Temperature Anomaly - " , degree, "C")))
# Summary table using tapply()
  Enso_mean<- tapply(AnomC, list(Enso_f, GISS_dec), FUN= "mean", digits = 1)
  Enso_mean
## I copied Enso_mean table to Excel and formatted it in Excel