{"action":"opened","issue":{"url":"https://api.github.com/repos/pytraj/pytraj/issues/475","labels_url":"https://api.github.com/repos/pytraj/pytraj/issues/475/labels{/name}","comments_url":"https://api.github.com/repos/pytraj/pytraj/issues/475/comments","events_url":"https://api.github.com/repos/pytraj/pytraj/issues/475/events","html_url":"https://github.com/pytraj/pytraj/issues/475","id":91034393,"number":475,"title":"basic tutorial: slicing trajectory","user":{"login":"hainm","id":4451957,"avatar_url":"https://avatars.githubusercontent.com/u/4451957?v=3","gravatar_id":"","url":"https://api.github.com/users/hainm","html_url":"https://github.com/hainm","followers_url":"https://api.github.com/users/hainm/followers","following_url":"https://api.github.com/users/hainm/following{/other_user}","gists_url":"https://api.github.com/users/hainm/gists{/gist_id}","starred_url":"https://api.github.com/users/hainm/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/hainm/subscriptions","organizations_url":"https://api.github.com/users/hainm/orgs","repos_url":"https://api.github.com/users/hainm/repos","events_url":"https://api.github.com/users/hainm/events{/privacy}","received_events_url":"https://api.github.com/users/hainm/received_events","type":"User","site_admin":false},"labels":[{"url":"https://api.github.com/repos/pytraj/pytraj/labels/Tutorial","name":"Tutorial","color":"fbca04"}],"state":"open","locked":false,"assignee":null,"milestone":null,"comments":0,"created_at":"2015-06-25T18:01:47Z","updated_at":"2015-06-25T18:01:47Z","closed_at":null,"body":"* get single frame\r\n```python\r\nIn [18]: traj[0]\r\nOut[18]: <Frame with 304 atoms>\r\n```\r\n\r\n* get new trajectory\r\n```python\r\nIn [19]: traj[2:8]\r\nOut[19]:\r\n<pytraj.Trajectory with 6 frames: <Topology with 1 mols, 20 residues, 304 atoms, \r\n310 bonds, non-PBC>>\r\n```\r\n\r\n*  get new trajectory having only CA atoms\r\n```python\r\nIn [20]: traj[2:8, '@CA']\r\nOut[20]:\r\n<pytraj.Trajectory with 6 frames: <Topology with 20 mols, 20 residues, 20 atoms, \r\n0 bonds, non-PBC>>\r\n```\r\n\r\n* get single coordinate for an atom\r\n```python\r\n# traj[0, 0, :] # xyz coordinate of first atom in first frame\r\nIn [21]: traj[0, 0, :]\r\nOut[21]: array([-16.492,  12.434, -11.018])\r\n```\r\n"}}