python - How do I sum tuples in a list where the first value is the same? -

-

i have list of stocks , positions tuples. positive buy, negative sell. example:

p = [('aapl', 50), ('aapl', -50), ('ry', 100), ('ry', -43)]

how can sum positions of stocks, current holdings?

result = [('aapl', 0), ('ry', 57)]

how this? can read collections.defaultdict.

>>> collections import defaultdict >>> testdict = defaultdict(int) >>> p = [('aapl', 50), ('aapl', -50), ('ry', 100), ('ry', -43)] >>> key, val in p:         testdict[key] += val   >>> testdict.items() [('aapl', 0), ('ry', 57)]

Comments

Post a Comment

Popular posts from this blog

vb.net - Alternative to the T-SQL AS keyword -

-
please see code below: imports system.data.sqlclient imports system.configuration public class form1 private _constring string private sub form1_load(byval sender object, byval e system.eventargs) handles me.load dim objdr sqldatareader dim objcommand sqlcommand dim objcon sqlconnection dim id integer try _constring = configurationmanager.connectionstrings("testconnection").tostring objcon = new sqlconnection(_constring) objcommand = new sqlcommand("select person.urn, car.urn person inner join car on person.urn = car.urn , personid=1") objcommand.connection = objcon objcon.open() objdr = objcommand.executereader(connectionstate.closed) while objdr.read id = objdr("urn") 'line 19 loop objdr.close() ...
Read more

php - MySQLi binding parameters in a prepared statement doesn't work unless inserted after "WHERE" -

-
i have php code pulls info database. uses prepared statement, works fine written below: <?php $n = '5'; if ($stmt = $connection->prepare("select title items id = ?")) { $stmt->bind_param("s", $n); $stmt->execute(); $stmt->bind_result($title); while ($stmt->fetch()) { echo $title; } $stmt->close(); } ?> and let's echo "batman". however, when move placeholder here: "select ? items id = 5" and change: $n = 'title'; instead of echoing "batman", echoes "title". not possible use placeholder select parameter? what have done this: select "title" items id = 5 you cant use prepared statement bindings identifiers, parameters.
Read more

ios - CFRelease causing crash in iPad application -

-
i trying merge 4 images make 1 uiimage. when going cfrelease, crashing. if don't this, giving memory leak , crashing. how resolved? see below code. referenceview.frame = cgrectmake(0, 0, 1024, 768); referenceview.hidden = no; [self.view insertsubview:referenceview belowsubview:selfview]; imgview1.image = delegate.imagecroped; imgview2.image = [uiimage imagenamed:@"videobg.png"]; imgview3.image = [uiimage imagenamed:@"videochar.png"];; imgview4.image = smileview.image; imgview1.frame = cgrectmake(456, 311, delegate.imagecroped.size.width-30.8, delegate.imagecroped.size.height-40); imgview2.frame = cgrectmake(0, 0, 1024, 768); imgview3.frame = cgrectmake(392, 187, imgview3.image.size.width, imgview3.image.size.height); imgview4.frame = cgrectmake((smileview.frame.origin.x-((smileview.frame.origin.x > 530) ? 30 : 15)), (smileview.frame.origin.y+((smileview.frame.origin.y <= 307) ? 95 : 50)), smile...
Read more