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Weirdness in plot with NULL values #822
Description
Details for the issue
Found a bug with our Plot code when trying some things out. It seems like any column whose first value is NULL gets excluded from the plot list. For example, the downloads_this_hour field isn't shown on the Plot panel:
After adjusting the SQL query so the first result isn't NULL, the column shows up:
Useful extra information
I'm opening this issue because:
- DB4S has a bug
I'm using DB4S on:
- Mac OS: ( version: 10.11.6 )
I'm using DB4S version:
- 3.9.1
- Other: git master e76e5b3
Activity
MKleusberg commentedon Oct 13, 2016
I vaguely remember that there already is an issue which at least mentions this. However I cannot remember coming to a conclusion there. The problem is this: you obviously can't text values or something similar; all our plotting supports is numbers and dates. Now NULL isn't a text value but it's not a number either. We could treat it as zero and it would all work as expected but from a data point of view this would be wrong. 0 means there is data and its value is 0, whereas NULL means there is no data and no value. What we could check is if it's possible to plot it in cases like yours anyways and just have a gap in the graph where there is a NULL data point.
justinclift commentedon Oct 13, 2016
For a NULL value, that means there's nothing to plot at that increment. eg it's an unknown value, so can't be put anywhere
So yeah, a gap in the graph at the NULL data point is probably the right approach. 😄
plot: Allow plotting of column when there is a NULL value in it
MKleusberg commentedon Oct 13, 2016
Should be fixed 😃 Can you give it a quick test, Justin?
MKleusberg commentedon Oct 13, 2016
Found it! This is a duplicate of issue #513 😃
MKleusberg commentedon Oct 13, 2016
Also see issue #499.
justinclift commentedon Oct 13, 2016
@MKleusberg Sorry for the delay. Was away from my OSX desktop.
Tested latest master here, this is fixed now. 😄
Another win for you @MKleusberg. 😁
plot: Allow plotting of column when there is a NULL value in it