#Define the working directory going to Session and then to Set Working Directory and Choose Directory
setwd("C:/Users/gsyla/OneDrive/Notes/Xanthi")

#read external data
flow1 = read.table("Strymon_discharge.txt",header = TRUE, dec=".")

#pass data from list to vector
flow = flow1$Discharge

#compute descriptive statistics 
mean.flow = mean(flow)  #mean discharge (m^3/s)
median.flow = median(flow)
range = range(flow)
range.flow = range[2]-range[1]
sd.flow = sd(flow)
var.flow = var(flow)
IQR.flow = IQR(flow)
summary(flow)

#Compute skewness
install.packages("e1071")
library(e1071)
skewness.flow = skewness(flow,type=1)
kurtosis.flow = kurtosis(flow,type=1)

#Plot histogram of Strymon River flow data
hist(flow,
     main="Histogram of Strymon River data",
     xlab = "Discharge, m^3/s",
     xlim = c(0,600),
     breaks = seq(0,600,by=50),
     col = "blue")

#Plot boxplot of Strymon River flow data
boxplot(flow,
        main = "Boxplot of Strymon River",
        xlab = "Strymon",
        ylab = "River Discharge, m^3/s",
        ylim = c(0,600),
        col = "red")

#Fit probability density function to data
install.packages("fitdistrplus")
library(fitdistrplus)

plotdist(flow,
         histo=TRUE,
         demp=TRUE)

descdist(flow)

#fit Weibull probability model on Strymon river data
fw = fitdist(flow1$Discharge,
             "weibull",
             method = "mle",
             lower = c(0,0),
            start = list(scale = 1, shape = 1))
summary(fw)

dweibull(500, # seq(0,100,by=10),
         shape = 1, 
         scale = 70.48,
         log = FALSE)

pweibull(500,
         shape = 1,
         scale = 70.48,
         log = FALSE,
         lower.tail = FALSE)

random_river = rweibull(1000,
                       shape = 1,
                       scale = 70.48)