TonyLadson

####################################################################
#
# Influence of shape factor in regional flood estimation
# See https://tonyladson.wordpress.com/2016/04/13/shape-factor-in-regional-flood-estimation/
#
####################################################################


# Plot of shape factor distribution

TonyLadson

# Find parameters of the Pearson III distribution given three quantile values


# Function for the Pearson III frequency factor
# details at https://tonyladson.wordpress.com/2015/03/10/frequency-factors-2/

Ky_gamma <- function(g, aep){
  
  if(abs(g) < 1e-8) { # Use the Wilson-Hilferty approximation to avoid numerical
    # issues near zero

TonyLadson

#remove(list = objects())


library(stringr)
library(dplyr)
library(ggplot2)
library(devtools)
library(readr)
library(repmis)

TonyLadson

###########################################################################################
#
#  Fitting non-linear models in R
#  See tonyladson
#  
#  5 June 2016
###############################################################################################
#
# Example data come from Figure 5 from Ian Cordery's thesis
# Also Figure 3 from Cordery, 1970

TonyLadson

# Confidence intervals for the mean for non-normal data
# See https://tonyladson.wordpress.com/2016/01/11/plotting-water-quality-samples-on-a-hydrograph/


# Modified Cox function for calculating confidence intervals for the mean
# Based on Olsson, 2005
# http://www.amstat.org/publications/jse/v13n1/olsson.html

# x is a set of log-normal data

TonyLadson

library(stringr)
library(readr)
library(dplyr)
library(lubridate)
library(ggplot2)
library(scales)
library(treemap)


#__________________________________________________________________________________________

TonyLadson

# Function to calculate 100% saturated dissolved oxygen in mg/L as a function of temperature in degrees Celcius

Calc_DOsat100 = function(temp){

# temp = temperature in degrees C
# relationship between temperature and dissolved oxygen as defined by the APHA
# American Public Health Association (1992)
# Standard methods for the examination of water and wastewater. 18th ed. Washington DC.

# Required constants

TonyLadson

# Function to calculate 100% saturated dissolved oxygen in water in mg/L as a function of temperature in degrees Celcius

Calc_DOsat100 = function(temp){
  
  # temp = temperature in degrees C
  # relationship between temperature and dissolved oxygen as defined by the APHA
  # American Public Health Association (1992)
  # Standard methods for the examination of water and wastewater. 18th ed. Washington DC.
  
  # Required constants

TonyLadson

# Convert from 'HH:MM:SS' to fractions of a day
# This also works with HH.HHHH
# and is vectorised

Time_convert <- function(x){
  
  f <- function(x,y){
    as.numeric(x)/60 + as.numeric(y)
    }
  split_time <- str_split(x, ':')

TonyLadson

Count_censored <- function(my.df) {
  
    # number left censored
  .Count_leftCensored <- function(x) {
    sum(str_detect(x, '[<]'), na.rm = TRUE)
  }
  
  .Count_rightCensored <- function(x) {
    sum(str_detect(x, '[>]'), na.rm = TRUE)
  }