<p>Hello, 
I am having a hard time opening a very large bedgraph. I have been suggested to split my <a href='http://samtools.sourceforge.net/SAM1.pdf'>bam</a> file by chromosome with chrom-bed.py but it didn't work.
Is there any other alternative?
Thanks,
GP.</p>

Try samtools: `samtools view -?`

<blockquote>
  <p>A region should be presented in one of the following formats:
       `chr1',`chr2:1,000' and `chr3:1000-2,000'. When a region is
       specified, the input alignment file must be an indexed BAM file.</p>
</blockquote>

something like `samtools view in.bam chr1 > chr1.bam` should work