CODEWITHSUNDEEP
rdataframe
Ernsthaft
Ernsthaft

Reputation: 177

Identify Week in Column of Dates and Generate Automatic Dataframe Subsets per Week

I want to automatise a code that calculates transport times. I would like that the code gives me 4 months that you can choose out of a big readout from a year and splits up the last month in its four weeks and just describes the data subsets (describing is not the problem).

Generating subsets from a dataset for chosen months is not the problem because I can define the months. But where I struggle is the 3/4 weeks of the last month. I need to identify them automatically and after that generate the subsets. (I hope that generating subsets should be easier after identifying.)

I can give you a little mock-up of my data.

dates <- as.Date(c("2019-01-07", "2019-01-08", "2019-01-09", 
               "2019-01-15", "2019-01-21"))

number <- c(12,13,14,15,20)

df <- data.frame(number, dates)

The original df contains of 60 variables but I believe this simple mockup can provide enough info for the task.

I am pretty new to r, I have no idea how to solve the problem, I will show you how I solved it with the months, but as said, in this case they are defined.

function(data = df, m1 = "01" , m2 = "02") {

Monat1 <- subset(data, format.Date(dates  , "%m") == m1)

Thank you for helping me out a bit.

Upvotes: 0

Views: 58

Answers (2)

Hunaidkhan
Hunaidkhan

Reputation: 1443

You can do it using base R and lubridate

Data

dates <- as.Date(c("2019-01-07", "2019-01-08", "2019-01-09", 
                   "2019-01-15", "2019-01-21"))

number <- c(12,13,14,15,20)

df <- data.frame(number, dates)
str(df)

Answer

library(lubridate)
df$condition <- ifelse(month(df$dates) == month(Sys.Date())-1,week(df$dates),"-")

condition will check if the date is less than a month ago or not and if yes it will give you week number for that particular value

Upvotes: 0

Jagge
Jagge

Reputation: 978

you can use the function strftime

strftime(df$dates, format = "%W")

in rstudio use 

?strftime()

to see all the different values you can extract from a date or POSIXCT object

Upvotes: 3

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