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Glitches

Ryan Wick edited this page Jul 1, 2018 · 7 revisions

This page illustrates read glitches using dotplots. The dotplots comparing a sequence in Badread before glitches are added on the x axis and after glitches (but before sequencing errors) on the y axis.

Glitches are controlled by three parameters (as a comma-delimited list of numbers):

  • glitch rate: how often glitches occur
  • glitch size: how much random sequence is added to the read
  • glitch skip: how much read sequence is lost

Rate

5000,100,100 1000,100,100 200,100,100

The three dotplots above show 10 kbp reads where the glitch rate is varied. You can see that the smaller the value, the smaller the space between glitches.

Size and skip

1000,100,0 1000,0,100 1000,100,100

These dotplots show the effect of the size and skip parameters. The first has a size of 100 and a skip of 0. This means that each glitch adds random sequence but loses no real sequence, resulting in a longer glitched sequence. The second is the opposite, a size of 0 and a skip of 100, where the glitched sequence is shorter than the original. The third has size and skip both equal to 100, so the glitched sequence should on average be the same length as the original.

Default setting and no glitches

The examples shown above are particularly glitchy to illustrate the concept. Badread's default value is 10000,25,25 for a modest amount of glitches. Or you can use 0,0,0 to turn glitches off entirely:

10000,25,25 0,0,0
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