Subset a data frame based on date

[usman]

I have daily flow data for 47 years.I want to seprate my data based on dates more specfically based on months. I face following error while trying to execute
dataset <- read_xlsx("BQ.Flow.xlsx")
as.Date(dataset[["Date"]], "%y-%m-%d")
sub.data <- selectByDate(dataset, start = "1971-01-01", end = "2017-12-31", year = 1971, month =
c("dec", "jan", "feb"))

Error in as.Date.default(x, ...) : do not know how to convert 'x' to class “Date”

[andresrcs]

@usman

as.Date(dataset[["Date"]], "%y-%m-%d")

In base R, objects doesn't get edited "in-place", you have to explicitly assign changes.

dataset$Date <- as.Date(dataset$Date, "%y-%m-%d")

[usman]

@usman

sub.data <- selectByDate(dataset, start = "1971-01-01", end = "2017-12-31", year = 1971, month =
c("dec", "jan", "feb"))

I did it but again same error is coming

[andresrcs]

To help us help you, could you please prepare a reproducible example (reprex) illustrating your issue and including sample data? Please have a look at this guide, to see how to create one:

FAQ: How to do a minimal reproducible example ( reprex ) for beginners

A minimal reproducible example consists of the following items: A minimal dataset, necessary to reproduce the issue The minimal runnable code necessary to reproduce the issue, which can be run on the given dataset, and including the necessary information on the used packages. Let's quickly go over each one of these with examples: Minimal Dataset (Sample Data) You need to provide a data frame that is small enough to be (reasonably) pasted on a post, but big enough to reproduce your issue. Let's say, as an example, that you are working with the iris data frame head(iris) #> Sepal.Length Sepal.Width Petal.Length Petal.Width Species #> 1 5.1 3.5 1.4 0.…