python - Pandas calculate year over year (or any other index) change in rows -

-

say have dataframe such:

               b  c  d            ---  -- -- --  2012-01-01 aaa  11 22 33 2013-01-01 aaa  11 23 53 2014-01-01 aaa  11 78 96   2012-01-01 bbb  12 42 24 2013-01-01 bbb  13 97 91 2014-01-01 bbb  14 25 12

(index datetime)

i want figure out change in column c between first appearance of aaa , last (in case 78-22 = 56). doing pivoting table years columns across top , adding difference column. there better way without modifying table?

if has many groups, may consider using groupby. assume df dataframe work with.

a = df.groupby("a")["c"] newt = a.last() - a.first()  print(newt)

the result:

a aaa    56 bbb   -17 name: c, dtype: int64

Comments

Post a Comment

Popular posts from this blog

ruby on rails - RuntimeError: Circular dependency detected while autoloading constant - ActiveAdmin.register Role -

-
i using activeadmin , have file doing this: activeadmin.register role something--- end however, server gives me error: runtimeerror: circular dependency detected while autoloading constant role /library/ruby/gems/2.0.0/gems/activesupport-4.0.10/lib/active_support/dependencies.rb:461:in `load_missing_constant' /library/ruby/gems/2.0.0/gems/activesupport-4.0.10/lib/active_support/dependencies.rb:184:in `const_missing' ~/desktop/boxfox/app/admin/role.rb:1:in `<top (required)>' /library/ruby/gems/2.0.0/gems/activesupport-4.0.10/lib/active_support/dependencies.rb:424:in `load' /library/ruby/gems/2.0.0/gems/activesupport-4.0.10/lib/active_support/dependencies.rb:424:in `block in load_file' /library/ruby/gems/2.0.0/gems/activesupport-4.0.10/lib/active_support/dependencies.rb:616:in `new_constants_in' /library/ruby/gems/2.0.0/gems/activesupport-4.0.10/lib/active_support/dependencies.rb:423:in `load_file' /library/ruby/gems/2.0.0/gems/activesuppor...
Read more

c++ - OpenMP unpredictable overhead -

-
i have simple openmp code runs 4 empty threads , reports time: #include "omp.h" #include <sys/time.h> #include <cstdio> double start_time; void process_thread() { } int main(){ struct timeval tv; gettimeofday(&tv, null); start_time = 1000*((double)tv.tv_sec + 1e-6*(double)tv.tv_usec); printf("beginning time: %.3fms ",start_time-start_time); #pragma omp parallel schedule(static,1) for(int i=0;i<4;i++) process_thread(); gettimeofday(&tv, null); double cur_time = 1000*((double)tv.tv_sec + 1e-6*(double)tv.tv_usec); printf("finishing time: %.3fms\n\n",cur_time-start_time); } without openmp running time small , consistent: beginning time: 0.000ms finishing time: 0.050ms beginning time: 0.000ms finishing time: 0.050ms beginning time: 0.000ms finishing time: 0.049ms beginning time: 0.000ms finishing time: 0.049ms beginning time: 0.000ms finishing time: 0.050ms beginnin...
Read more

django rest framework - DRF 3.0: UniqueTogetherValidator with a read-only field -

-
in process of upgrading django rest framework 3.0 2.4.4 , want have read-only user field, failing because 'user' being required uniquetogethervalidator (i think) i have model (excuse typos, simplified , code works fine irl): class examplemodel(models.model): some_attr = models.positivesmallintegerfield() other_attr = models.positivesmallintegerfield() user = models.foreignkey(user) class meta: unique_together = ('some_attr', 'other_attr', 'user') viewset: class exampleviewset(viewsets.modelviewset): queryset = examplemodel.objects.all() serializer_class = exampleserializer def perform_create(self, serializer): serializer.save(user=self.request.user) def perform_update(self, serializer): serializer.save(user=self.request.user) serializer: class exampleserializer(serializers.modelserializer): user = userserializer(read_only=true) class meta: model = examplemodel n...
Read more