indexing

问题 I'm not sure sure how to interpret this, but all the queries I run in sql server 2005 have a "query cost (relative to batch)" of 100%. Is there any way to reduce the cost? 回答1: If your batch (what you are executing within a given call) has one query then relative to that batch that query takes up 100% as it is the only query within that batch. I.e.: BEGIN SELECT * FROM table -- Will be 100% of batch END BEGIN SELECT * FROM table -- Will be 50% of batch SELECT * FROM table -- Will be 50% of

问题 I believe the following function is a working solution for pandas DataFrame rolling argmin/max: import numpy as np def data_frame_rolling_arg_func(df, window_size, func): ws = window_size wm1 = window_size - 1 return (df.rolling(ws).apply(getattr(np, f'arg{func}'))[wm1:].astype(int) + np.array([np.arange(len(df) - wm1)]).T).applymap( lambda x: df.index[x]).combine_first(df.applymap(lambda x: np.NaN)) It is inspired from a partial solution for rolling idxmax on pandas Series. Explanations:

问题 Beginner here, learning python, was wondering something. This gives me the second element: list = [1,2,3,4] list.index(2) 2 But when i tried this: list = [0] * 5 list[2] = [1,2,3,4] list.index[4] I get an error. Is there some way to pull the index of an element from an array, no matter what list it's placed into? I know it's possible with dictionaries: info = {first:1,second:2,third:3} for i in info.values: print i 1 2 3 Is there something like that for lists? 回答1: The index method does not

问题 Beginner here, learning python, was wondering something. This gives me the second element: list = [1,2,3,4] list.index(2) 2 But when i tried this: list = [0] * 5 list[2] = [1,2,3,4] list.index[4] I get an error. Is there some way to pull the index of an element from an array, no matter what list it's placed into? I know it's possible with dictionaries: info = {first:1,second:2,third:3} for i in info.values: print i 1 2 3 Is there something like that for lists? 回答1: The index method does not

问题 Beginner here, learning python, was wondering something. This gives me the second element: list = [1,2,3,4] list.index(2) 2 But when i tried this: list = [0] * 5 list[2] = [1,2,3,4] list.index[4] I get an error. Is there some way to pull the index of an element from an array, no matter what list it's placed into? I know it's possible with dictionaries: info = {first:1,second:2,third:3} for i in info.values: print i 1 2 3 Is there something like that for lists? 回答1: The index method does not

问题 Is it possible to list all indices in a db using sqlalchemy? 回答1: yes. from sqlalchemy import create_engine from sqlalchemy.engine import reflection engine = create_engine('...') insp = reflection.Inspector.from_engine(engine) for name in insp.get_table_names(): for index in insp.get_indexes(name): print index 来源： https://stackoverflow.com/questions/5605019/listing-indices-using-sqlalchemy

问题 Is it possible to list all indices in a db using sqlalchemy? 回答1: yes. from sqlalchemy import create_engine from sqlalchemy.engine import reflection engine = create_engine('...') insp = reflection.Inspector.from_engine(engine) for name in insp.get_table_names(): for index in insp.get_indexes(name): print index 来源： https://stackoverflow.com/questions/5605019/listing-indices-using-sqlalchemy

问题 Is it possible to list all indices in a db using sqlalchemy? 回答1: yes. from sqlalchemy import create_engine from sqlalchemy.engine import reflection engine = create_engine('...') insp = reflection.Inspector.from_engine(engine) for name in insp.get_table_names(): for index in insp.get_indexes(name): print index 来源： https://stackoverflow.com/questions/5605019/listing-indices-using-sqlalchemy

问题 Closed . This question needs details or clarity. It is not currently accepting answers. Want to improve this question? Add details and clarify the problem by editing this post. Closed 3 months ago . Improve this question I have created table name as d with ID column as primary key and then just inserted records as shown in output, but after fetching all records this output still displayed same as order in which records are inserted. but output as a see now not in ordered form. 回答1: PostgreSQL

问题 Closed . This question needs details or clarity. It is not currently accepting answers. Want to improve this question? Add details and clarify the problem by editing this post. Closed 3 months ago . Improve this question I have created table name as d with ID column as primary key and then just inserted records as shown in output, but after fetching all records this output still displayed same as order in which records are inserted. but output as a see now not in ordered form. 回答1: PostgreSQL