set a start time and date to a dataset - r

I'm struggling with setting compute the time in my dataset.
The file is named as a time and date, so I did use this code make it as a starting date:
'''df$time <- ymd_hms("2020-02-16 03:39:00")'''
In my dataframe I have distance and speed , so to compute the time I should use this code:
'''time <- distance*3600/ df$SPEED'''
but the problem is that the new column is stable ("2020-02-16 03:39:00") instead of showing the moving in time.
any help please?

Related

How to convert a weekly dataset into a time series in R

i have a WEEKLY dataset that start on 1986.01.03 and end on 2022-10-07.
The problem is when I forecast the time series with Arima +garch, because the date in T0 is wrong, i.e. 1975 enter image description here.
The function that I used to convert the dataset into time series is here, but I think that the problem is here, since it doesn't take on the right date.
FutureWeekly= ts(WeeklyFuture$FutureWeekly, start= c(1986,1), end = c(2022,10), frequency = 52)
does anyone know how to convert a weekly dataset to time series other than this?
There are the first rows of my dataset and then I have to transform that into returns (diff(log(FutureWeekly) to do the ARMA+GARCH
enter image description here
Try this:
futures<-c(WeeklyFuture$FutureWeekly) #convert to vector
FutureWeekly= ts(futures, start= c(1986,1,10), end = c(1986,3,7), frequency = 52) #add day of week ending on
One of the things ts() demands is a vector of values. I think it might also be easier for ts() to convert the data if it was able to see the 7-day increments.
Assuming you have full un-broken weekly data for the entire period, I think these two things will solve the problem.

My data does not convert to time series in R

My data contains several measurements in one day. It is stored in CSV-file and looks like this:
enter image description here
The V1 column is factor type, so I'm adding a extra column which is date-time -type: vd$Vdate <- as_datetime(vd$V1) :
enter image description here
Then I'm trying to convert the vd-data into time series: vd.ts<- ts(vd, frequency = 365)
But then the dates are gone:
enter image description here
I just cannot get it what I am doing wrong! Could someone help me, please.
Your dates are gone because you need to build the ts dataframe from your variables (V1, ... V7) disregarding the date field and your ts command will order R to structure the dates.
Also, I noticed that you have what is seems like hourly data, so you need to provide the frequency that is appropriate to your time not 365. Considering what you posted your frequency seems to be a bit odd. I recommend finding a way to establish the frequency correctly. For example, if I have hourly data for 365 days of the year then I have a frequency of 365.25*24 (0.25 for the leap years).
So the following is just as an example, it still won't work properly with what I see (it is limited view of your dataset so I am not sure 100%)
# Build ts data (univariate)
vs.ts <- ts(vd$V1, frequency = 365, start = c(2019, 4)
# check to see if it is structured correctly
print(vd.ts, calendar = T)
Finally my time series is working properly. I used
ts <- zoo(measurements, date_times)
and I found out that the date_times was supposed to be converted with as_datetime() as otherwise they were character type. The measurements are converted into data.frame type.

Changing a string of factors to time

I am trying to take a column of my data that is in factor format and change it to time in the format
hours:minutes:seconds:milliseconds
I tried:
start.times <- as.POSIXct(as.character(start.times), format="%H:%M:%OS")
but it returned values with todays date and left out the milliseconds in them and that is not what I want.
I also tried downloading chron and running the code:
start.times <- times(start.times)
but this just returned NA's.....
Please help!
My data is all about start times and end times of dolphin vocalizations and I am trying to find the mean whistle duration and the inter whistle interval. Anyways, I don't really know how to get my data into the format I need it in. Thank you!
Assuming you have a factor that looks like:
start.time <- c("0:13:45.9", "3:09:44.9")
Then what you wrote should work if you change the last colon to a period
as.POSIXct(start.time, format ="%H:%M:%S.%OS")

How to get monthly time series cross sectional into zoo using R

I want to get a panel data set into zoo so that it catches both month and year. My data set looks like this.
and the data can be downloaded from HERE.
The best way I could do is,
dat<-read.csv("dat_lag.csv")
zdat <- read.zoo(dat, format="%d/%m/%Y")
However, I could do this by including column 1- Date and column 4- Day in my data set. Is there any clever way to get both month and year into zoo using R without including the Date and Day columns? Thanks, in advance for any help.

Getting Date to Add Correctly

I have a 3000 x 1000 matrix time series database going back 14 years that is updated every three months. I am forecasting out 9 months using this data still keeping a 3200 x 1100 matrix (mind you these are rough numbers).
During the forecasting process I need the variables Year and Month to be calculated appropriately . I am trying to automate the process so I don't have to mess with the code any more; I can just run the code every three months and upload the projections into our database.
Below is the code I am using right now. As I said above I do not want to have to look at the data or the code just run the code every three months. Right now everything else is working as planed, but I still have to ensure the dates are appropriately annotated. The foo variables are changed for privacy purposes due to the nature of their names.
projection <- rbind(projection, data.frame(foo=forbar, bar=barfoo,
+ Year=2012, Month=1:9,
+ Foo=as.vector(fc$mean)))
I'm not sure exactly where the year/months are coming from, but if you want to refer to the current date for those numbers, here is an option (using the wonderful package, lubridate):
library(lubridate)
today = Sys.Date()
projection <- rbind(projection, data.frame(foo=foobar, bar=barfoo,
year = year(today),
month = sapply(1:9,function(x) month(today+months(x))),
Foo = as.vector(fc$mean)))
I hope this is what you're looking for.

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