I have a wide data frame in R and I am trying to rename the column names so that I can reshape it to a long format.
Currently, the data is structured like this:
long lat V1 V2 V3 V4 V5 V6 V7 V8 V9 V10 ... V477
I'd like to rename the columns so that they are:
long lat Jan_1979 Feb_1979 Mar_1979 Apr_1979 ... Sept_2018
I'm not sure how to go about doing this. Any help would be appreciated.
There are multiple ways you could do this.
One way in base R is by using seq to create monthly dates in the format you need. So for example, you could create first 10 sequence starting from 1979-01-01 by
format(seq(as.Date('1979-01-01'), length.out = 10, by = "1 month"), "%b_%Y")
#[1] "Jan_1979" "Feb_1979" "Mar_1979" "Apr_1979" "May_1979" "Jun_1979" "Jul_1979"
#[8] "Aug_1979" "Sep_1979" "Oct_1979"
For your case, this should work
names(df)[3:479] <- format(seq(as.Date('1979-01-01'),
length.out = 477, by = "1 month"), "%b_%Y")
We can use expand.grid to get all month year combinations:
name_combn <- expand.grid(month.abb, 1979:2018)[1:477,]
names(df) <- c('long', 'lat', paste(name_combn$Var1, name_combn$Var2, sep = "_"))
Output:
> head(name_combn, 20)
Var1 Var2
1 Jan 1979
2 Feb 1979
3 Mar 1979
4 Apr 1979
5 May 1979
6 Jun 1979
7 Jul 1979
8 Aug 1979
9 Sep 1979
10 Oct 1979
11 Nov 1979
12 Dec 1979
13 Jan 1980
14 Feb 1980
15 Mar 1980
16 Apr 1980
17 May 1980
18 Jun 1980
19 Jul 1980
20 Aug 1980