The easiest way to convert a data frame to a time series object in R is to use the read.zoo() function from the zoo package:

tseries <- read.zoo(df)

The following example shows how to use this function in practice.

Example: Convert Data Frame to Time Series in R

Suppose we have the following data frame in R:

#create data frame
df <- data.frame(date = as.Date('2022-01-01') + 0:9,
                 sales = runif(10, 10, 500) + seq(50, 59)^2)

#view data frame
df

         date    sales
1  2022-01-01 2797.159
2  2022-01-02 2782.148
3  2022-01-03 2801.773
4  2022-01-04 3257.546
5  2022-01-05 3415.920
6  2022-01-06 3267.564
7  2022-01-07 3577.496
8  2022-01-08 3627.193
9  2022-01-09 3509.547
10 2022-01-10 3670.815

We can use the class() function to confirm that df is currently a data frame:

#display class of df
class(df)

[1] "data.frame"

To convert the data frame to a time series object, we can use the read.zoo() function from the zoo package:

library(zoo)#convert data frame to time series
tseries <- read.zoo(df)

#view time series
tseries

2022-01-01 2022-01-02 2022-01-03 2022-01-04 2022-01-05 2022-01-06 2022-01-07 
  2797.159   2782.148   2801.773   3257.546   3415.920   3267.564   3577.496 
2022-01-08 2022-01-09 2022-01-10 
  3627.193   3509.547   3670.815 

And we can use the class() function to confirm that tseries has a “zoo” time series class.

#display class of tseries
class(tseries)

[1] "zoo"

We can use also use the as.ts() function to convert the “zoo” time series object to a “ts” time series object:

#convert to ts object
tseries_ts <- as.ts(tseries)

#view time series object
tseries_ts

Time Series:
Start = 18993 
End = 19002 
Frequency = 1 
 [1] 2797.159 2782.148 2801.773 3257.546 3415.920 3267.564 3577.496 3627.193
 [9] 3509.547 3670.815

#view class
class(tseries_ts)

[1] "ts"

Depending on your end goal, it might make more sense to convert the data frame to a “zoo” time series object or a “ts” time series object.