Null values in a TTree Branch

danche · May 30, 2013, 6:35am

Hi,

I have a TTree with a branch “rw7_qelNCma[4]” that was giving some anomalous values. Went I looked up those element with a TTree::Scan, they were empty.

[quote]root [9] gst->Scan(“rw7_qelNCma[4]”,"","",1000000,2750)

Row * rw7_qelNC *

```
2750 *         1 *
```
```
2751 *         1 *
```
```
2752 * 1.0378572 *
```
```
2753 *         1 *
```
```
2754 *         1 *
```
```
2755 *         1 *
```
```
2756 *         1 *
```
```
2757 *         1 *
```
```
2758 *         1 *
```
```
2759 *         1 *
```
```
2760 *         1 *
```
```
2761 *         1 *
```
```
2762 * 1.8582798 *
```
```
2763 *           *
```
```
2764 *         1 *
```
```
2765 *         1 *
```
```
2766 *         1 *
```
```
2767 *         1 *
```
```
2768 *         1 *
```
```
2769 * 1.0825097 *
```
```
2770 *         1 *
```
```
2771 *         1 *
```
```
2772 *         1 *
```
```
2773 *         1 *
```
```
2774 *         1 *
```

Type to continue or q to quit ==>
[/quote]

these ‘blank’ entries should be filled with 1. When I loop over the tree they return the last non-unity value. For example entry 2763 returns a value of 1.8582798 instead of 1, 0 or null. Is there any way to way to check for these entries and set the value to 1.

Thanks,

Dan

pcanal · June 25, 2013, 2:09pm

Hi Dan,

Those empty lines indicates that the array has less than 4 elements in these entries.

[quote] When I loop over the tree they return the last non-unity value.[/quote]This usually indicates that you are looking at a variable size array but are not correctly checking the array bound.

Cheers,
Philippe.