Sequence

Recommented way to implement observable collections in Python?

由 大兔子大兔子 提交于 2021-02-07 19:51:00
问题 I would like to have some observable collections/sequences in Python that allow me to listen on change events, like for adding new items or updating items: list = ObservableList(['a','b','c']) list.addChangeListener(lambda new_value: print(new_value)) list.append('a') # => should trigger the attached change listener data_frame = ObservableDataFrame({'x': [1,2,3], 'y':[10,20,30]}) data_frame.addChangeListener(update_dependent_table_cells) # => allows to only update dependent cells instead of a

Recommented way to implement observable collections in Python?

由 本秂侑毒 提交于 2021-02-07 19:47:13
问题 I would like to have some observable collections/sequences in Python that allow me to listen on change events, like for adding new items or updating items: list = ObservableList(['a','b','c']) list.addChangeListener(lambda new_value: print(new_value)) list.append('a') # => should trigger the attached change listener data_frame = ObservableDataFrame({'x': [1,2,3], 'y':[10,20,30]}) data_frame.addChangeListener(update_dependent_table_cells) # => allows to only update dependent cells instead of a

Trees on the level UVA

由 本小妞迷上赌 提交于 2021-02-07 17:01:23
Trees are fundamental in many branches of computer science (Pun definitely intended). Current stateof-the art parallel computers such as Thinking Machines’ CM-5 are based on fat trees . Quad- and octal-trees are fundamental to many algorithms in computer graphics. This problem involves building and traversing binary trees. Given a sequence of binary trees, you are to write a program that prints a level-order traversal of each tree. In this problem each node of a binary tree contains a positive integer and all binary trees have have fewer than 256 nodes. In a level-order traversal of a tree,

Oracle Database-别无选择时的EXP导出数据手记

由 ╄→尐↘猪︶ㄣ 提交于 2021-02-07 12:20:41
更多精彩内容，请登录： ke.sandata.com.cn 如今已经是Oracle Database 21c的时代了，你是否还考虑过使用EXP/IMIP这些9i中的工具呢？ 其实在特殊的场景中，这些看似“老的工具”，也是可以帮助你解决棘手的问题。 比如：可以在数据库只读模式下，导出数据等。又或者将其应用在我下文中所描述的场景中。 进入正题，某客户找到我，描述了其数据库无法启动的故障，经过分析得出数据库软件被注入了恶意的代码，导致TAB$表数据被删除，从而无法启动数据库，告警日志里面的输出如下： Errors in file D:\APP\ADMINISTRATOR\diag\rdbms\xxxx\xxxx\trace\xxxx_ora_13308.trc (incident=26578): ORA-00600: 内部错误代码, 参数: [16703], [1403], [20], [], [], [], [], [], [], [], [], [] Incident details in: D:\APP\ADMINISTRATOR\diag\rdbms\xxxx\xxxx\incident\incdir_26578\xxxx_ora_13308_i26578.trc Use ADRCI or Support Workbench to package the incident.

linux之iptables详解

由 时光怂恿深爱的人放手 提交于 2021-02-07 12:16:03
iptables/netfilter是一组工具 netfilter：是内核中的一个过滤框架，规则生效位置的框架 iptables:是一个能生防火墙规则，并能将规则附加在netfilter上的，真正实现数据报文过滤和规则生成的工具 网络：IP报文首部 ①ipv4(4bit) Hdr Len首步-长度(4bit) type of service(8bit) total lenght(16bit) ②Identification(Fragment ID 16bits)段标识:数据报文传在网络传输的时候，如果两个网络设备之间支持接收的数据报文大小不同的时候，要 实行分片机制，所以每个分片的报文都有一个标识符，从而实现在对端设备进行重组 MF:更多的分片；DF：不进行分片；R：返回错误信息； Fragment Offset:片偏移量 0表示第一个 ③Time-To-Live(TTL 8bits) 生存时间 Protocol(8bits)协议:tcp ucp icmp(互联网控制消息协议) Header首部校验和Checksum(16bits):存放报文首部检验码，接收方可通过首部校验码查看首部报文是否有问题 ④Source IP Address源IP地址(32bits): 源IP地址信息 ⑤Destination IP Address(32bits): 目的IP地址信息 ⑥Options

How to apply a function to multiple columns to create multiple new columns in R?

由 我只是一个虾纸丫 提交于 2021-02-07 10:30:14
问题 I've this list of sequences aqi_range and a dataframe df : aqi_range = list(0:50,51:100,101:250) df PM10_mean PM10_min PM10_max PM2.5_mean PM2.5_min PM2.5_max 1 85.6 3 264 75.7 3 240 2 105. 6 243 76.4 3 191 3 95.8 19 287 48.4 8 134 4 85.5 50 166 64.8 32 103 5 55.9 24 117 46.7 19 77 6 37.5 6 116 31.3 3 87 7 26 5 69 15.5 3 49 8 82.3 34 169 49.6 25 120 9 170 68 272 133 67 201 10 254 189 323 226 173 269 Now I've created these two pretty simple functions that i want to apply to this dataframe to

how can I maintain sequence of my list using set?

由 徘徊边缘 提交于 2021-02-07 08:16:45
问题 In [1]: l1 = ['a',2,3,0,9.0,0,2,6,'b','a'] In [2]: l2 = list(set(l1)) In [3]: l2 Out[3]: ['a', 0, 2, 3, 6, 9.0, 'b'] Here you can see the the list l2 is falling with different sequence then the original l1, I need to remove the duplicate elements from my list without changing the sequence/order of the list elements.... 回答1: If you are not concerned with efficiency, this is O(n*m) >>> sorted(set(l1), key=l1.index) ['a', 2, 3, 0, 9.0, 6, 'b'] Using an intermediate dict is more complicated, but

Difference between a[:] = b and a = b[:]? (Python)

由 会有一股神秘感。 提交于 2021-02-07 01:54:44
问题 I was asked this for a coding test and didn't know the answer. Anyone have any ideas? 回答1: [:] is the slice operator. When it's on the left side, it overwrites the contents of the list without creating a new reference. When it's on the right side, it creates a copy of the list with the same contents. 回答2: a = b[:] calls either __getslice__ or __getitem__ on b and assigns the result to a . In nearly all cases (e.g. lists, tuples, and other sequence types), this makes a shallow copy of the

Difference between a[:] = b and a = b[:]? (Python)

由 白昼怎懂夜的黑 提交于 2021-02-07 01:53:23
问题 I was asked this for a coding test and didn't know the answer. Anyone have any ideas? 回答1: [:] is the slice operator. When it's on the left side, it overwrites the contents of the list without creating a new reference. When it's on the right side, it creates a copy of the list with the same contents. 回答2: a = b[:] calls either __getslice__ or __getitem__ on b and assigns the result to a . In nearly all cases (e.g. lists, tuples, and other sequence types), this makes a shallow copy of the

Difference between a[:] = b and a = b[:]? (Python)

由 我与影子孤独终老i 提交于 2021-02-07 01:53:22
问题 I was asked this for a coding test and didn't know the answer. Anyone have any ideas? 回答1: [:] is the slice operator. When it's on the left side, it overwrites the contents of the list without creating a new reference. When it's on the right side, it creates a copy of the list with the same contents. 回答2: a = b[:] calls either __getslice__ or __getitem__ on b and assigns the result to a . In nearly all cases (e.g. lists, tuples, and other sequence types), this makes a shallow copy of the
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