python - Is Pandas 0.16.1 groupby().apply() method applying function more than once to the same group? -


this question has answer here:

i have noticed in cases pandas 0.16.1, apply() function on groupby() being applied more once 1 or more of output groups. here reproduction:

in [1]:  df2 = dataframe ({"a" : ["alpha", "alpha", "alpha", "beta","beta","beta","beta","gamma"]}) df2 ["b"] = series ([i in range(0,len(df2))]) df2  out [1]:       b 0   alpha   0 1   alpha   1 2   alpha   2 3   beta    3 4   beta    4 5   beta    5 6   beta    6 7   gamma   7  in [2]:  def my_func (df):     print(df.index)  in [3]:  df2.groupby("a").apply(my_func)  out [3]: int64index([0, 1, 2], dtype='int64') int64index([0, 1, 2], dtype='int64') int64index([3, 4, 5, 6], dtype='int64') int64index([7], dtype='int64')

notice [0,1,2] index appearing twice in output. seem indicate function applied alpha group twice.

this not huge issue, since it's practice these functions idempotent in first place. however, if functions costly in terms of runtime (think big regression runs, etc.), can more of problem.

am using api incorrectly and/or misinterpreting output, or there possible issue here?

according doc (http://pandas.pydata.org/pandas-docs/dev/generated/pandas.dataframe.apply.html)

in current implementation apply calls func twice on first column/row decide whether can take fast or slow code path.


Comments

Post a Comment

Popular posts from this blog

javascript - Bootstrap Popover: iOS Safari strange behaviour -

i looking through twitter bootstrap documentation, , i'm interested in implementing dismissible popover when button clicked. here example bootstrap's docs: http://getbootstrap.com/javascript/#dismiss-on-next-click when press "dismissible popover" button os x safari browser works fine. when access same link above ios safari, button not work. is, popover not dismissed on click. why button not working ios safari? the example linked using data-trigger="focus" attribute. try changing data-trigger="click" . <a tabindex="0" class="btn btn-lg btn-danger" role="button" data-toggle="popover" data-trigger="click" title="dismissible popover" data-content="and here's amazing content. it's engaging. right?">dismissible popover</a>
Read more

Magento/PHP - Get phones on all members in a customer group -

i working on custom magento extension. working around adminhtml part , i've created custom form there. here form code: <?php class vivasindustries_smsnotification_block_adminhtml_sms_sendmass_edit_form extends mage_adminhtml_block_widget_form { public function _preparelayout() { $extensionpath = mage::getmoduledir('js', 'vivasindustries_smsnotification'); $head = $this->getlayout()->getblock('head'); $head->addjs('jquery.js'); $head->addjs('vivas.js'); return parent::_preparelayout(); } protected function _prepareform() { $form = new varien_data_form(array( 'id' => 'edit_form', 'action' => $this->geturl('*/*/save', array('id' => $this->getrequest()->get...
Read more

session - Logging Out Using PHP -

i have seen other programs regarding can't seem make work. doing wrong? want achieve after user logged out, going previous pages become restricted. i have 3 php files: 1. sample.php - main page username , password filled in 2. successful.php - user's page after logging in 3. logout.php - destorys session hinder user access pages after logging out sample.php </html> <form action="" method="post"> <table> <tr> <td>username:</td> <td>password:</td> </tr> <tr> <td><input type="text" name="username"></td> <td><input type="password" name="password"></td> </tr> <tr> <td><input type="submit" value="submit" name="submit"></td> </tr> </table> </form> </html> <?php $servername = "localhost"; $username = ...
Read more