asosnovsky asosnovsky - 2 months ago 43
R Question

Converting data.frame to xts order.by requires an appropriate time-based object

I have this following data frame:

> head(table,10)
Date Open High Low Close Volume Adj.Close
1 2014-04-11 32.64 33.48 32.15 32.87 28040700 32.87
2 2014-04-10 34.88 34.98 33.09 33.40 33970700 33.40
3 2014-04-09 34.19 35.00 33.95 34.87 21597500 34.87
4 2014-04-08 33.10 34.43 33.02 33.83 35440300 33.83
5 2014-04-07 34.11 34.37 32.53 33.07 47770200 33.07
6 2014-04-04 36.01 36.05 33.83 34.26 41049900 34.26
7 2014-04-03 36.66 36.79 35.51 35.76 16792000 35.76
8 2014-04-02 36.68 36.86 36.56 36.64 14522800 36.64
9 2014-04-01 36.16 36.86 36.15 36.49 15734000 36.49
10 2014-03-31 36.46 36.58 35.73 35.90 15153200 35.90


I am trying to make it into a xts file using

> table3<-xts(table[,-1],order.by=table$Date)


but I get this error:

Error in xts(table[, -1], order.by = table$Date) :
order.by requires an appropriate time-based object


Where did I go wrong? I thought that the table$Date were organized as time-based.

Answer

?xts says that the following about order.by:

Currently acceptable classes include: ‘Date’, ‘POSIXct’, ‘timeDate’, as well as ‘yearmon’ and ‘yearqtr’ where the index values remain unique.

So an extra explicit conversion is required, e.g. to POSIXct:

xts(table[, -1], order.by=as.POSIXct(table$Date))
            Open  High   Low Close   Volume Adj.Close
2014-03-31 36.46 36.58 35.73 35.90 15153200     35.90
2014-04-01 36.16 36.86 36.15 36.49 15734000     36.49
2014-04-02 36.68 36.86 36.56 36.64 14522800     36.64
2014-04-03 36.66 36.79 35.51 35.76 16792000     35.76
2014-04-04 36.01 36.05 33.83 34.26 41049900     34.26
2014-04-07 34.11 34.37 32.53 33.07 47770200     33.07
2014-04-08 33.10 34.43 33.02 33.83 35440300     33.83
2014-04-09 34.19 35.00 33.95 34.87 21597500     34.87
2014-04-10 34.88 34.98 33.09 33.40 33970700     33.40
2014-04-11 32.64 33.48 32.15 32.87 28040700     32.87

Another option:

xts(table[, -1], order.by=as.Date(table$Date))