Smooth Weight from Text File Created by IFTTT

smooth_weight.R

INPUT_PATH <- "~/Dropbox/Text Notes/Weight.txt"
OUTPUT_PATH <- "~/Dropbox/Text Notes/Weight Stats.txt"

library(lubridate)
library(ggplot2)
library(zoo)

# READ FILE
con <- file(INPUT_PATH, "rt")
lines <- readLines(con)
close(con)

# PARSE INTO LISTS OF WEIGHTS AND DATES
parse.line <- function(line) {
  s <- strsplit(line, split=" ")[[1]]
  date.str <- paste(s[2:10][!is.na(s[2:10])], collapse=" ")
  date <- mdy_hm(date.str, quiet=TRUE)
  l <- list(as.numeric(s[1]), date)
  names(l) <- c("weight", "date")
  l
}
list.weight.date <- lapply(lines, parse.line)
weights <- lapply(list.weight.date, function(X) X$weight)
dates <- lapply(list.weight.date, function(X) X$date)

# BUILD DATA FRAME
df <- data.frame(weight = unlist(weights), date = do.call("c", dates) )

# CREATE TIME SERIES AND RESAMPLE
ts <- zoo(c(df$weight), df$date)
ts <- aggregate(ts, time(ts), tail, 1)
g <- round(seq(start(ts), end(ts), 60 * 60 * 24), "days")
ts <- na.approx(ts, xout = g)

# FUNCTION TO GET WEIGHT N-DAYS AGO IF WEIGHT IS SMOOTHED BY ROLLING MEDIAN
# OVER A GIVEN (smooth.n) NUMBER OF DAYS
days.ago <- function(days, smooth.n) {
  date <- head(tail(index(ts),days + 1),1)
  smoothed <- rollmedianr(ts, smooth.n)
  as.numeric(smoothed[date])
}

# SMOOTH WEIGHT BY 29 DAYS AND GENERATE SOME SUMMARY STATS
days = 29
current.weight <- days.ago(0, days)
x <- c(current.weight, 
       current.weight-days.ago(7, days), 
       current.weight-days.ago(30, days), 
       current.weight-days.ago(365, days),
       current.weight-max(ts))
x = round(x, 1)
names(x) = c("current", "7days", "30days", "365days", "max")


fileConn<-file(OUTPUT_PATH)
w <- c(paste("Weight (lbs):", x["current"]),
       paste("Total Δ:", x["max"]),
       paste("1 Week Δ:", x["7days"]),
       paste("1 Month Δ:", x["30days"]),
       paste("1 Year Δ:", x["365days"]))
writeLines(w,fileConn)
close(fileConn)