I have a bedgraph file which I have loaded up into R and I am wanting to convert it to a wig file for further analysis. In R, my bedgraph file looks like this:

1   0
2   0
3   0
4   0

I am wanting to add the header variableStep chrom=1 as the first line. I then want to convert this bedgraph file to wig. Does anyone know how to do this? I want my output file to look like this:

variableStep chrom=1
1   0
2   0
3   0
4   0

Check the rtracklayer package documentation if you really want to do this in R. Or check the kentUtils set of command line tools for conversion utilities from and to the bedGraph/Wig/bigWig formats. I am not sure if you can directly go from bg to Wig with them but for sure from bg to bigWig and then there is a tool to go from bigWig to Wig. It's quite uncommon these days to use Wig anyway, check if you really need that.