Baghal, Basel (NIH/NIAAA) [F] wrote: > Hello, > > I have encountered a problem when visualizing my custom Wig tracks. I first > noticed that after loading the files, some of the tracks were missing peaks > for very long stretched (sometimes an entire arm of a chromosome) while the > files themselves do contain the data.
Thank you for the example data Basel. As I mentioned in my email response to you, this is a particular extreme example of how the wiggle encoding can distort the display of the data. The encoding takes 1024 data input points and spreads them over 256 bins to turn them all into a single byte. In your first set of 1024 data values, the maximum value is 1692845 and the lowest value is 0. When those values are put into 256 bins, this makes the "width" of each bin: 1692845/256 = 6612 Since your data values each cover 50,000 bases, that first set of 1024 data values spans a significant portion of the chromosome, 51200000 bases, almost all of it appearing as zero. Most of the other values in this set of 1024 are less than 6612 and thus end up in the bin 0 and come back out as the value zero when decoded. Almost all of that appears as a zero in the display, with just the maximum value showing up as a spike in the display. In this case, bigWig is the only answer to this display situation. Sorry for the inconvenience. --Hiram _______________________________________________ Genome maillist - [email protected] https://lists.soe.ucsc.edu/mailman/listinfo/genome
