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kandi X-RAY | gb Summary
I may change it in the future but at the moment it is like this this:.
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QUESTION
I am analyzing large (between 0.5 and 20 GB) binary files, which contain information about particle collisions from a simulation. The number of collisions, number of incoming and outgoing particles can vary, so the files consist of variable length records. For analysis I use python and numpy. After switching from python 2 to python 3 I have noticed a dramatic decrease in performance of my scripts and traced it down to numpy.fromfile function.
Simplified code to reproduce the problemThis code, iotest.py
- Generates a file of a similar structure to what I have in my studies
- Reads it using numpy.fromfile
- Reads it using numpy.frombuffer
- Compares timing of both
ANSWER
Answered 2022-Mar-16 at 23:52TL;DR: np.fromfile
and np.frombuffer
are not optimized to read many small buffers. You can load the whole file in a big buffer and then decode it very efficiently using Numba.
The main issue is that the benchmark measure overheads. Indeed, it perform a lot of system/C calls that are very inefficient. For example, on the 24 MiB file, the while
loops calls 601_214 times np.fromfile
and np.frombuffer
. The timing on my machine are 10.5s for read_binary_npfromfile
and 1.2s for read_binary_npfrombuffer
. This means respectively 17.4 us and 2.0 us per call for the two function. Such timing per call are relatively reasonable considering Numpy is not designed to efficiently operate on very small arrays (it needs to perform many checks, call some functions, wrap/unwrap CPython types, allocate some objects, etc.). The overhead of these functions can change from one version to another and unless it becomes huge, this is not a bug. The addition of new features to Numpy and CPython often impact overheads and this appear to be the case here (eg. buffering interface). The point is that it is not really a problem because there is a way to use a different approach that is much much faster (as it does not pay huge overheads).
The main solution to write a fast implementation is to read the whole file once in a big byte buffer and then decode it using np.view
. That being said, this is a bit tricky because of data alignment and the fact that nearly all Numpy function needs to be prohibited in the while loop due to their overhead. Here is an example:
QUESTION
Description
How to fix this error. I have created simple project with latest version and when try to build the project via Xcode
it generate error?
Version
0.67.3
Output of
npx react-native info
ANSWER
Answered 2022-Feb-27 at 07:55You could create that into the library source or you could avoid it and use the same UIColor option just above it.
I removed: ( [RCTConvert UIColor:options.cancelButtonTintColor() ? @( options.cancelButtonTintColor()) : nil];* ) and replace it with: ( *[RCTConvert UIColor:options.tintColor() ? @(options.tintColor()) : nil]; )
my line now looks like:
QUESTION
I am implementing a simple chatbot using keras and WebSockets. I now have a model that can make a prediction about the user input and send the according answer.
When I do it through command line it works fine, however when I try to send the answer through my WebSocket, the WebSocket doesn't even start anymore.
Here is my working WebSocket code:
...ANSWER
Answered 2022-Feb-16 at 19:53There is no problem with your websocket route. Could you please share how you are triggering this route? Websocket is a different protocol and I'm suspecting that you are using a HTTP client to test websocket. For example in Postman:
HTTP requests are different than websocket requests. So, you should use appropriate client to test websocket.
QUESTION
C2x, 7.21.9.2 The fseek function:
Synopsis
...
ANSWER
Answered 2022-Feb-13 at 16:31The C Standard was formalized in 1990 when most hard drives were smaller than 2 GB. The prototype for fseek()
was already in broad use with a long
type offset and 32 bits seemed large enough for all purposes, especially since the corresponding system call used the same API already. They did add fgetpos()
and fsetpos()
for exotic file systems where a simple long offset did not carry all the necessary information for seeking, but kept the fpos_t
type opaque.
After a few years, when 64-bit offsets became necessary, many operating systems added 64-bit versions of the system calls and POSIX introduced fseeko()
and ftello()
to provide a high level interface for larger offsets. These extensions are not necessary anymore for 64-bit versions of common operating systems (linux, OS/X) but Microsoft decided to keep it's long
, or more precisely LONG
, type at 32-bits, solidifying this issue and other ones too such as size_t
being larger than unsigned long
. This very unfortunate decision plagues C developers on Win64 platforms ever since and forces them to use non portable APIs for large files.
Changing fseek
and ftell
prototypes would create more problems with existing software as it would break compatibility, so it will not happen.
Some other historical shortcomings are even more surprising, such as the prototype for fgets
:
QUESTION
I'm getting this error:
...ANSWER
Answered 2022-Feb-06 at 12:57Please, consider trying to follow the instruction from quarkus/faq.adoc at main · quarkusio/quarkus:
1. Native compilationNative executable fails on macOS with
error: unknown type name 'uint8_t'
Your macOS has the wrong
*.h
files compared to the OS and no gcc compilation will work. This can happen when you migrate from versions of the OS. See Cannot compile any C++ programs; error: unknown type name 'uint8_t'The solution is to
sudo mv /usr/local/include /usr/local/include.old
- Reinstall XCode for good measure
- (optional?)
brew install llvm
- generally reinstall your brew dependencies with native compilation
The executable should work now.
The purpose of (the idea behind) renaming the include
directory (from include
to include.old
) seems to be explained in the answer.
- Related question. May contain some possible solutions. Broken c++ std libraries on macOS High Sierra 10.13 - Stack Overflow.
QUESTION
I have a music note datatype defined like so:
data Note = Ab | A | Bb | B | C | Db | D | Eb | E | F | Gb | G deriving (Eq, Ord)
How can i make it an instace of Enum
so that succ G
returns Ab
?
ANSWER
Answered 2022-Jan-09 at 14:33You have to define the Enum
instance yourself:
QUESTION
My computer uses a CPT of Intel(R) Core(TM) i7-10750H CPU @ 2.60GHz 2.59 GHz. Also my RAM memory size is 16 GB. When I run the following panel VAR model "pvargmm" in R,
...ANSWER
Answered 2021-Dec-14 at 00:24Not an answer, but this might help someone else answer this. I coded this to re-create a data.frame of the size @Eric is working with.
QUESTION
I have a file of IDs called IDs_list.txt that I want to use in order to extract information from a second file which has hundreds of IDs, many of which are not in my specific IDS_list.txt.
I've tried combinations of if and grep but my results keep coming up empty.
Here is an example of what I'm trying to do and what I've done.
...ANSWER
Answered 2021-Dec-17 at 15:16You may use this awk
:
QUESTION
I was working on currency switcher. i call method on click the link and after method successful want it to reload. but reload is not working at all. currency getting stored in cookie, if i refresh page manually it gets updated in navbar too, but i want it to reload automatically once method complete.
here is the code in navbar..
...ANSWER
Answered 2021-Nov-30 at 23:04Quick solution might be to pass reload
as an optional parameter to setCurrency
QUESTION
I am working on a .Net 6.0 project, and I want to migrate from Newtonsoft.Json to System.Text.Json. So far most is working, except the following:
I've got this json:
...ANSWER
Answered 2021-Nov-22 at 13:39The System.Text.Json
library doesn't deserialize to fields. If you change your class to use a property instead, your sample JSON will deserialize as expected.
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