# Why the connectivity paths only have non-zeros density/intensity at the last few entries

**URL:** <https://community.brain-map.org/t/why-the-connectivity-paths-only-have-non-zeros-density-intensity-at-the-last-few-entries/1025>\
**Category:** Technical\
**Tags:** api, atlas-mouse-brain-connectivity, connectivity, allensdk\
**Created:** [April 6, 2021, 5:12pm UTC](https://community.brain-map.org/t/why-the-connectivity-paths-only-have-non-zeros-density-intensity-at-the-last-few-entries/1025 "2021-04-06T17:12:44Z")\
**Posts on this page:** 1\
**Page:** 1

<div class="post-metadata">

**Author:** ![orio](https://avatars.discourse-cdn.com/v4/letter/o/e99b99/32.png) [@orio](https://community.brain-map.org/u/orio)\
**Post date:** [April 6, 2021, 5:12pm UTC](https://community.brain-map.org/t/why-the-connectivity-paths-only-have-non-zeros-density-intensity-at-the-last-few-entries/1025/1 "2021-04-06T17:12:44Z")

</div>

I tried to extract the paths of mouse brain connectivity of the injection experiments. Taking one path `lines[60]['path']` as an example, why only the third to last and second to last entries have non-zero values for density and intensity?

It’s not just the case for `lines[60]`. I also tried other `lines[i]`, and I noted that generally only the second to last (or third to last as well) entries are non-zeros, and all other entries are zeros. Why would that happen?

```auto

injection_data_set_id = 156394513

x = 4400
y = 3300
z = 5600

url = LINES_FMT % (x, y, z, injection_data_set_id)

connection = urllib.request.urlopen(url)
response_text = connection.read()
response = json.loads(response_text)

lines = response['msg']

print(lines[60]['path'])

```