I have a situation where I need to convert a data frame object into XTS object. The first column of my data frame is always a date object and is always named "Date". However, i would not know apriori, whether my dataframe object has 1 column (excluding the date) or more columns.
The issue is this: When i try to convert the dataframe object into xts using xts(), the resulting XTS object has the correct column names when the dataframe object has more than 1 columns. BUT if it has only one data column (excluding the date), it loses its column name. See the code below.
dv <- as.Date(c("2010-01-31", "2010-02-28", "2010-03-31"))
DF <- data.frame(Date = dv, C1 = c(1,2,3), C2 = c(10,20,30))
DF.subset <- data.frame(Date = dv, C1 = c(1,2,3))
DF.TS <- xts(DF[,-1], order.by =dv)
DF.subset.TS <- as.xts(DF.subset[,-1], order.by =dv)
> head(DF.TS)
C1 C2
2010-01-31 1 10
2010-02-28 2 20
2010-03-31 3 30
> head(DF.subset.TS)
[,1]
2010-01-31 1
2010-02-28 2
2010-03-31 3
> colnames(DF.TS)
[1] "C1" "C2"
> colnames(DF.subset.TS)
NULL
Why am I losing the column name (and how to avoid losing it) in the second instance (DF.subset.TS)? Any help is highly appreciated please.
When you have only one column in the data the default nature is to drop it's dimensions and convert it into vector.
DF.subset[,-1]
#[1] 1 2 3
To avoid that and keep dataframe as dataframe you can use drop = FALSE.
DF.subset[,-1, drop = FALSE]
# C1
#1 1
#2 2
#3 3
Now using it in xts function.
library(xts)
DF.TS <- xts(DF[,-1, drop = FALSE], order.by =dv)
DF.subset.TS <- as.xts(DF.subset[,-1, drop = FALSE], order.by =dv)
colnames(DF.TS)
#[1] "C1" "C2"
colnames(DF.subset.TS)
#[1] "C1"