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python - pandas How to "quickly" get the first and last rows of tens of millions of data groups?

I hope to get the first and last rows of each group after pandas grouping. The current method is to traverse the group for name, group in xxx: and then group.iloc[0] group.iloc[-1], but this is not suitable for thousands of Traversing thousands of data is very slow. Is there any faster method?

大家讲道理 2017-05-18 10:48:04

How can I deconstruct a json file to display all the content in the site? Every time I load everything at once I get thousands of objects and chrome crashes

Every time I load everything at once I get thousands of objects and chrome crashes. btn.addEventListener('click',function(){event.preventDefault();asyncfunctiongetData(){constresponse=awaitfetch(url)constdata=awaitresponse.json();info(data)}getData();f

P粉545682500 2024-02-17 19:07:24

What happens if I use thousands of setTimeouts?

Have a website on the server side via node.js, every time I refresh the page it generates a new code, I want to detect if 24 hours have passed since the last code generation, the problem is that for me to do that I need to figure out the 24 hours Is this past the point, if I use setTimeout() on the ...

P粉811349112 2023-09-10 15:08:09

objective-c - How to speed up reading 50 million data from a file and storing it in a vector using C++?

I need to read 50 million double data from a txt file and store it in a vector. I initially thought that the file io might be too slow, so I used file memory mapping to read all the file contents into memory as blocks, and then Then push_back into the vector one by one, but directly from the file...

PHP中文网 2017-05-31 10:36:40

nginx has set up an IP blacklist. The list is very long. There are thousands of entries at present. I wonder if it will affect the performance of nginx?

Because of being attacked by dynamic IPs, I added nginx's IP blacklist (deny IP) through a script. It has reached thousands. This blacklist will become longer and longer. I wonder if it will affect the normal access performance of nginx. Influence?

过去多啦不再A梦 2017-05-16 17:17:23

How to upload large video files? I would like to ask how to upload videos from the Chinese website?

Now there is a need to upload a video file with a size of several hundred megabytes. How should the upload be processed to speed up the upload speed? The current upload speed of 300 megabytes takes about 20 minutes. Is there any solution, such as format selection? Conversion processing, etc. How is ...

微尘 2020-04-02 17:19:35

objective-c - A problem about memory release under ARC in iOS development

Click the button on page 1 to jump to page 2. At this time, the memory increases by 5 MB. Then click the button on page 2 to dismiss page 2. At this time, the dealloc method of page 2 is executed, but the 5 MB memory is not released. Why? Isn't the memory under ARC released in time? How should we ju...

曾经蜡笔没有小新 2017-07-03 11:43:05

apache - Using Appache to set up a file server on Windows, the speed is very slow

I used Appache to set up a file server on Windows. The local machine can access and download dozens of megabits per second, while other LAN machines only have 200-300kb/s.

phpcn_u1582 2017-05-16 16:58:58

Thousand separator PHP

I extracted this $number=100000.5; from the database. What I need is to set the format to 100.000,5str_replace+number_format I guessed it. My replace works perfectly, echostr_replace('.',',',$row['anskaf_sum']); (returns: 100000,5) but when I add number_format, I somehow fail with number_format($row...

P粉848442185 2023-11-07 12:00:02

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