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How to compress alphanumeric strings?

由 假装没事ソ 提交于 2021-01-22 08:52:14
问题 I want to shrink Strings like -1234B56789C;ABC1D3E/FGH4IJKL which are approx 20 - 25 case-insensitive chars. My goal is to have an alphanumeric string that is a maximum of 16 characters. They must remain human readable. Is that possible? Are there algorithms that can be used to compress alphanumeric string that also has some special chars? It must also be possible to revert the compression. 回答1: I think in general it's not possible unless you use a different target alphabet. As far as I

Does Python support zero-copy I/O?

由 被刻印的时光 ゝ 提交于 2021-01-21 03:45:41
问题 I have two open file objects, dest and src . File object dest is opened for writing, with the seek position placed at some offset within the file, and file object src is opened for reading. What I need to do is simply read from the current position in src to EOF and transfer the contents to dest as quickly as possible. If I were programming in Java, I could utilize the FileChannel#transferTo() method to perform zero-copy file I/O. Does Python also support zero-copy? 回答1: Since version 3.3,

What does the 0x80 port address connect to?

由 安稳与你 提交于 2021-01-20 19:19:06
问题 When sending a command and reading the data from a certain chip, say the RTC, different documents say that we should wait for some time before reading from the device to make sure the data is available. Many pieces of code make a dummy read from the port 0x80 . I wanted to know to what device this address location is connected, if any. I am talking with respect to the IA-32 PC architecture. 回答1: I/O port 0x80 is traditionally used for POST Codes. (POST = Power On Self Test) While the system

What does the 0x80 port address connect to?

由 我的未来我决定 提交于 2021-01-20 19:16:23
问题 When sending a command and reading the data from a certain chip, say the RTC, different documents say that we should wait for some time before reading from the device to make sure the data is available. Many pieces of code make a dummy read from the port 0x80 . I wanted to know to what device this address location is connected, if any. I am talking with respect to the IA-32 PC architecture. 回答1: I/O port 0x80 is traditionally used for POST Codes. (POST = Power On Self Test) While the system

What does the 0x80 port address connect to?

由 ￡可爱￡侵袭症＋ 提交于 2021-01-20 19:15:34
问题 When sending a command and reading the data from a certain chip, say the RTC, different documents say that we should wait for some time before reading from the device to make sure the data is available. Many pieces of code make a dummy read from the port 0x80 . I wanted to know to what device this address location is connected, if any. I am talking with respect to the IA-32 PC architecture. 回答1: I/O port 0x80 is traditionally used for POST Codes. (POST = Power On Self Test) While the system

Write NumPy array contents to a file in Python

由 坚强是说给别人听的谎言 提交于 2021-01-13 09:39:25
问题 I have a NumPy array that I'm trying to write to a file outfile.write(str(myarray)) But, I get something that looks like this: [ 4.275000000e01 2.345000000e01 3.2135000000e-02 ] My requirements are: To write the data within the array (and not the array braces []) To write the data with a certain number of trailing decimal places (say 6) Normally, #2 would not be that hard, but I'm not sure how to handle it in conjunction with #1 . I also want to write the array on one line as a row. like this

B树、B-树、B+树、B树都是什么

由 ≡放荡痞女 提交于 2021-01-10 07:27:24
B 树、 B- 树、 B+ 树、 B* 树都是什么 B 树 即二叉搜索树： 1. 所有非叶子结点至多拥有两个儿子（ Left 和 Right ）； 2. 所有结点存储一个关键字； 3. 非叶子结点的左指针指向小于其关键字的子树，右指针指向大于其关键字的子树； 如： B 树的搜索，从根结点开始，如果查询的关键字与结点的关键字相等，那么就命中；否则，如果查询关键字比结点关键字小，就进入左儿子；如果比结点关键字大，就进入右儿子；如果左儿子或右儿子的指针为空，则报告找不到相应的关键字； 如果 B 树的所有非叶子结点的左右子树的结点数目均保持差不多（平衡），那么 B 树的搜索性能逼近二分查找；但它比连续内存空间的二分查找的优点是，改变 B 树结构（插入与删除结点）不需要移动大段的内存数据，甚至通常是常数开销； 如： 但 B 树在经过多次插入与删除后，有可能导致不同的结构： 右边也是一个 B 树，但它的搜索性能已经是线性的了；同样的关键字集合有可能导致不同的树结构索引；所以，使用 B 树还要考虑尽可能让 B 树保持左图的结构，和避免右图的结构，也就是所谓的“平衡”问题； 实际使用的 B 树都是在原 B 树的基础上加上平衡算法，即“平衡二叉树”；如何保持 B 树结点分布均匀的平衡算法是平衡二叉树的关键；平衡算法是一种在 B 树中插入和删除结点的策略； B- 树 是一种多路搜索树（并不是二叉的）：

SwiftUI Button on top of a MKMapView does not get triggered

由 雨燕双飞 提交于 2021-01-05 11:32:43
问题 I have a button on top of a MKMapView. But the button does not get triggered when it's tapped on. Do you know what's missing? MapView.swift import SwiftUI import UIKit import MapKit struct MapView: UIViewRepresentable { func makeUIView(context: Context) -> MKMapView { let mkMapView = MKMapView() return mkMapView } func updateUIView(_ uiView: MKMapView, context: Context) { } func makeCoordinator() -> Coordinator { Coordinator() } class Coordinator: NSObject, MKMapViewDelegate { } } ContentView

Unable to mock open, even when using the example from the documentation

由 坚强是说给别人听的谎言 提交于 2021-01-03 10:36:50
问题 I've copied and pasted the following code directly from the Python mock docs: from unittest.mock import patch, mock_open with patch('__main__.open', mock_open(read_data='bibble')) as m: with open('foo') as h: result = h.read() m.assert_called_once_with('foo') assert result == 'bibble' When I run this I get the following error: AttributeError: <module '__main__' from 'path/to/file'> does not have the attribute 'open' Given that this is the example given in the documentation, I'm not sure where

Unable to mock open, even when using the example from the documentation

由 ╄→尐↘猪︶ㄣ 提交于 2021-01-03 10:33:34
问题 I've copied and pasted the following code directly from the Python mock docs: from unittest.mock import patch, mock_open with patch('__main__.open', mock_open(read_data='bibble')) as m: with open('foo') as h: result = h.read() m.assert_called_once_with('foo') assert result == 'bibble' When I run this I get the following error: AttributeError: <module '__main__' from 'path/to/file'> does not have the attribute 'open' Given that this is the example given in the documentation, I'm not sure where
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