Y-axis reference value change in bar graph

Question

Hi!

So when I plotted some of my data in bar graphs, as expected the y-axis starts from 0 and goes up. However, I was wondering if there's a way to set a new 'zero' for the axis? As in instead of zero, the axis uses a different number as the x-y crossing.

For example, my bar graphs actually are gene expression folds and the value 1.0 is the normal control. So say a graph is 0.5, it would be nice to show the bar going down from 1.0 instead of going up from 0. Is there a possible way to do this? I couldn't find this option in the y-axis settings.

Thanks so much!

vince_faller · Answer

I don't know of doing exactly what you're asking with just preferences.  You could just make a :data - control_value column and plot the deltas.  It will still be centered at zero but you might get the look you want.  You could then overwrite the 0 label with a reference line to make it seem like 0 isn't there.

txnelson · Answer

Here is a possible solution that is based upon creating a new column with values below zero, which will have the bar chart going down, and then changing the displayed axis values to positive values.

1. Create a new column with a formula that is equal to 0-<measurement column>

2. Go into the column properties for the new column, and go to Value Labels

3. Using ranges of data option, create new value labels where something like 0 to -.05 has a label of 0, and -.05 to -.1 has a label of .075, etc.

4. Go to Graph Builder and create your bar chart using the new column.

This all could be automated by developing a script to do the transformations