search for: firstdat

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2001 Feb 13
0
handle date variables
...2. How to convert a string into a date value. For example, convert 20010122 to 2001 Jan 22, and get its day of the week, i.e. Monday? 3. How to handle date variables in a loop? How to make the following codes work? And how users should pass the date arguments to the function? fun1 <- function(firstdate, lastdate) { for ( i in firstdate:lastdate) { do something.... } } fun1(2001/01/22, 2001/01/27) --- Douglas Bates <bates at stat.wisc.edu> wrote: > Yu-Ling Wu <yuling5 at yahoo.com> writes: > > > I'd like to pass a string to a function as the &g...
2011 Feb 09
1
Iterate over a list of input files?
...in the directory tested and augment the data frame I'm building to have more results columns.How can I do that? Here's the code: library(chron) # .Holidays / is.holiday / is.weekend TStoDate = function (TSDate) { X = strptime(TSDate + 19e6L, "%Y%m%d") return(as.Date(X)) } FirstDate = 1090601 LastDate = 1101101 StartDate = TStoDate(FirstDate) EndDate = TStoDate(LastDate) # Create a sequence of days from start to finish # Then remove weekends and holidays and turn into a data.frame dd <- seq(StartDate, EndDate, by = "day") TradingDate <- dd[!is.weekend(dd) &...
2013 Feb 11
2
Inserting rows of interpolated data
Dear help list - I have light data with 5-min time-stamps. I would like to insert four 1-min time-stamps between each row and interpolate the light data on each new row. To do this I have come up with the following code: lightdata <- read.table("Test_light_data.csv", header = TRUE, sep = ",") # read data file into object "lightdata" library(chron) mins <-
2024 Nov 27
4
R Processing dataframe by group - equivalent to SAS by group processing with a first. and retain statments
Check out the dplyr package, specifically the mutate function. # Create new column based on existing column value df <- df %>% mutate(FirstDay = if(ID = 2, 5)) df Repeat as needed to capture all of the day/firstday combinations you want to account for. Like everything else in R, there are probably at least a dozen other ways to do this, between base R and all of the library packages
2024 Nov 27
7
R Processing dataframe by group - equivalent to SAS by group processing with a first. and retain statments
I am an old, long time SAS programmer. I need to produce R code that processes a dataframe in a manner that is equivalent to that produced by using a by statement in SAS and an if first.day statement and a retain statement: I want to take data (olddata) that looks like this ID Day 1 1 1 1 1 2 1 2 1 3 1 3 1 4 1 4 1 5 1 5 2 5 2 5 2 5 2 6 2 6 2 6 3 10 3 10 and make it look like this: (withing each