Data dodania Pytanie
2017-10-11 22:10 Optimizing loop on large data file in R, perhaps using Rcpp »
I have a loop in R that that's quite slow (but works). Currently, this calculation takes about ~3 minutes on my laptop, and I think it can be improved...
(1) odpowiedzi
2017-10-11 20:10 Is there a way to remove the loop using numpy? »
I have a 3D numpy array input_data (q x m x n), that I am using to build histogram data to eventually plot, which is stored in plot_data (m x n x 2). ...
(2) odpowiedzi
2017-10-11 18:10 Using performance.mark() with Chrome dev tools performance tab »
I'd like to see my calls to performance.mark(...) show up on Chrome's dev tools Performance tab. All the documentation I can find online seem to refer...
(1) odpowiedzi
2017-10-11 12:10 CFML & SQL - Performance Increase? »
Brief Overview Okay, so I've written a query that will filter some products, however, I need to try and further tweak this query to allow for even mo...
(2) odpowiedzi
2017-10-10 21:10 which shader stage is more effitient for matrix transformation »
I have 2 questions about the glsl efficiency. In the fully user-defined shader pipeline vs -> tcs -> tes -> gs -> fs the first 4 stages are ab...
(1) odpowiedzi
2017-10-10 17:10 Why is groupby so fast? »
This is a follow up question to this one, where jezrael used pandas.DataFrame.groupby to increment by a factor of some hundreds the speed of a list cr...
(1) odpowiedzi
2017-10-10 05:10 Does Python load in function arguments into registers or does it keep them on the stack? »
So I'm writing a function that takes in a tuple as an argument and does a bunch of stuff to it. Here is what that looks like: def swap(self, locat...
(4) odpowiedzi
2017-10-09 20:10 Java EE, Spring clean code, can we use static methods? »
I need help, which version of code is better and why: @Component public class BodyEntityFactoryImpl implements BodyEntityFactory { public BodyEnt...
(0) odpowiedzi
2017-10-09 11:10 Slow queryAggreate in Aerospike with multithreading »
We're creating a Java client to write data directly into memory in Aerospike, and another Java client to read data from memory. Both clients are multi...
(2) odpowiedzi
2017-10-09 11:10 Cassandra read performance »
What causes Cassandra cluster to be 20% slower in read operations than a single-node cluster? I have set up a Cassandra cluster with 3 nodes and tes...
(1) odpowiedzi
2017-10-09 04:10 Is possible to get the state information from L1 cache line protocol in a different core? »
There are several cache coherence protocols around there, such as MSI, MESI, MOSI, MOESI, etc. Let's suppose this scenario: A CPU contains 4-cores wi...
(1) odpowiedzi
2017-10-07 19:10 R: improving speed for t-test for each row in a data frame »
I am trying to improve the speed of a t-test loop for a data-frame. I have a large data frame (~15000 rows and 205 columns). Each column is a cell an...
(2) odpowiedzi
2017-10-07 15:10 How to vectorize double dependence loop in Matlab? »
I have a loop function which the inner loop depends on the value of your outer loop. for jj = 1:500 for ii = jj:500 Gamma(ii,jj) =mod( ...
(1) odpowiedzi
2017-10-07 14:10 Fast complex SQL queries on PostgreSQL database with Python »
I have a large dataset with +50M records in a PostgreSQL database that require massive calculations, inner join. Python is the tool of choice with Ps...
(3) odpowiedzi
2017-10-06 15:10 ArrayList find custom object quickly »
I'm using ArrayList to store CustomObjects, problem is that it takes time to find an object in that list in order to remove it. (around 100K elements)...
(1) odpowiedzi
2017-10-06 10:10 Keep ffmpeg render as constant speed ( 3x ) »
I'm trying to render a video. But I want render it as constant speed. Example : ffmpeg -stream_loop -1 -i 113856_video_0.ts -c:v copy -c:a aac -b...
(1) odpowiedzi
2017-10-06 02:10 Interval lock Implementation »
I am looking for an implementation of interval lock. Given an interval (x, y), a thread can acquire the lock if no-one else is acquiring any interval ...
(2) odpowiedzi
2017-10-05 16:10 Recursive algorithm fails to complete tests in allotted time »
I was doing a test that required an algorithm for Binary Tomography. A set of 38 test values are supplied that test correctness, but there is also a t...
(2) odpowiedzi
2017-10-05 11:10 Why there is performance degradation after ~6 hours of Java 9 G1 work without the actual increase in load? »
I switched 1 instance (2 vCPU, 2GB RAM, load ~4k req/sec) to Java 9 (from latest Java 8). For a while, everything was fine and CPU usage was same as b...
(0) odpowiedzi
2017-10-05 00:10 My python code is taking 8+ hours to iterate over big data »
Update: It's been over 24 hours and the code is still not done yet :) I have this python code below. Basically, this code is currently only using 1% ...
(1) odpowiedzi
2017-10-04 21:10 Timing vs the "as-if" rule »
There is a great question about the "as-if" rule in general, but I wonder if there are any excpetions when it comes to measuring time. Consider this ...
(2) odpowiedzi
2017-10-04 15:10 Python element access performance »
being a long time C++ developer I just started working on algorithms in Python. I'm currently profiling my code to get a feel for how to program effic...
(1) odpowiedzi
2017-10-04 12:10 Merging multiple sql update statements(Oracle) »
I'm not very good at sql and I've tried a few things. What would be the best way to combine these 5 update statements into a single statement consider...
(3) odpowiedzi
2017-10-03 13:10 Why is the construction of std::optional<int> more expensive than a std::pair<int, bool>? »
Consider these two approaches that can represent an "optional int": using std_optional_int = std::optional<int>; using my_optional_int = std::p...
(4) odpowiedzi
2017-10-03 11:10 Where are DB calls being processed? »
I've created a dynamic paging model to present data in pages for my projects. In my controller I have two calls for the DB : public async Task&l...
(0) odpowiedzi
2017-10-03 10:10 Python - "xor"ing each byte in "bytes" in the most efficient way »
I have a "bytes" object and an "int" mask, I want to do a xor over all the bytes with my mask. I do this action repeatedly over big "bytes" objects (~...
(2) odpowiedzi
2017-10-03 07:10 How to sort a large array according to the alphabet specified in the array with a minimum loss of time? »
How I can sort array with million values by letters specified in the array effectively with minimal waste of time. $letters = array( "а","б", "в",...
(2) odpowiedzi
2017-10-02 23:10 Does std::unordered_map<int,float> still have to hash the integer to get to the value? »
I would like to know whether std::unordered_map< int, float > still has to hash the given integer to get to the value or just uses it straight a...
(2) odpowiedzi
2017-10-02 21:10 What is the difference between 'keys.each' and 'each_key'? »
When iterating through a hash like below: hash.keys.each do |key| process_key(key) end Rubocop proclaims I should use: each_key instead of: k...
(2) odpowiedzi
2017-10-02 14:10 What is the most efficient way to tune the settings of a sensor, such that it gives optimal readings? »
I have a fairly simple sensor which outputs a measured distance, with a number of adjustable parameters which determine how the sensor takes said meas...
(0) odpowiedzi
2017-10-02 12:10 Linq to objects: inner query performance »
During answering on one of questions I saw 2 examples of LINQ code which should work exactly same. But I was wonder about performance, and found that...
(1) odpowiedzi
2017-10-01 19:10 Find all records with Hebrew names »
I have a postgresql database with a users table, where each user has a name (in unicode). I'd like to find all users whose name contains at least one ...
(1) odpowiedzi
2017-10-01 16:10 WebApi proxy throughput »
I'm writing a web application with a bunch of backend micro-services, and a single gateway application handling concerns such as SSL offloading, autho...
(0) odpowiedzi
2017-10-01 11:10 How to keep content of oracle view v$sql more time? »
I try to analyse the cost of sql statement according v$sql result in Oracle database. But view's content is timing cleared. How should I do to keep c...
(1) odpowiedzi
2017-09-30 20:09 What are the relative cycle times for the 6 basic arithmetic operations? »
When I try to optimize my code, for a very long time I've just been using a rule of thumb that addition and subtraction are worth 1, multiplication an...
(1) odpowiedzi