transform data frame in time series for date type POSIXct - dataframe

Question

I have a data frame with the following two variables:
amount: num 1213.5 34.5 ...
txn_date: POSIXct, format "2017-05-01 12:13:30" ...
I want to transform it in a time series using ts().
I started using this code:
Z <- zoo(data$amount, order.by=as.Date(as.character(data$txn_date), format="%Y/%m/%d %H:%M:%S"))
But the problem is that in Z I loose the dates. In fact, all the dates are reported as NA.
How can I solve it?
For my analysis is important to have date in the format:%Y/%m/%d %H:%M:%S
for example 2017-05-01 12:13:30. I don't want to remove the time component in the variable txn_date.
Yhan you for your help,
Andrea

Answer 1

I think your prolem comes from the way you're manipulating your data frame, could post more details about it please ?
I think i have a fix for you.
Data frame I used :
> df1
$data
value
1 1.9150
2 3.1025
3 6.7400
4 8.5025
5 11.0025
6 9.8025
7 9.0775
8 7.0900
9 6.8525
10 7.4900
$date
%Y-%m-%d
1 1974-01-01
2 1974-01-02
3 1974-01-03
4 1974-01-04
5 1974-01-05
6 1974-01-06
7 1974-01-07
8 1974-01-08
9 1974-01-09
10 1974-01-10
> class(df1$data$value)
[1] "numeric"
> class(df1$date$`%Y-%m-%d`)
[1] "POSIXct" "POSIXt"
Then I can create a time serie by calling zoo like that :
> Z<-zoo(df1$data,order.by=(as.POSIXct(df1$date$`%Y-%m-%d`)))
> Z
value
1974-01-01 1.9150
1974-01-02 3.1025
1974-01-03 6.7400
1974-01-04 8.5025
1974-01-05 11.0025
1974-01-06 9.8025
1974-01-07 9.0775
1974-01-08 7.0900
1974-01-09 6.8525
1974-01-10 7.4900
The important thing here is that I use df1$date$%Y-%m-%d instead of just
df1$date
In fact if I try the way you did it I get NA values too :
> Z<-zoo(df1$data,order.by=as.POSIXct(as.Date(as.character(df1$date),format("%Y-%m-%d"))))
> Z
value
<NA> 1.915
To get the name of data$txn_date you can use the following command : names(data$txn_date) and try my solution with your data frame and name.
> names(df1$date)
[1] "%Y-%m-%d"