大约有 44,000 项符合查询结果（耗时：0.0406秒） [XML]
Frequency table for a single variable
... the columns as such
[my_series[c].value_counts() for c in list(my_series.select_dtypes(include=['O']).columns)]
Breakdown:
my_series.select_dtypes(include=['O'])
Selects just the categorical data
list(my_series.select_dtypes(include=['O']).columns)
Turns the columns f...
What is in your Mathematica tool bag? [closed]
...pplication of Reap and Sow which mimics/extends the behavior of GatherBy:
SelectEquivalents[x_List,f_:Identity, g_:Identity, h_:(#2&)]:=
Reap[Sow[g[#],{f[#]}]&/@x, _, h][[2]];
This allows me to group lists by any criteria and transform them in the process. The way it works is that a c...
When to use single quotes, double quotes, and backticks in MySQL
...ng query will produce different results (or errors) depending on SQL mode:
SELECT "column" FROM table WHERE foo = "bar"
ANSI_QUOTES disabled
The query will select the string literal "column" where column foo is equal to string "bar"
ANSI_QUOTES enabled
The query will select the column column where ...
Can't launch my app in Instruments: At least one target failed to launch
...To change your code signing identity for Xcode 6:
Click on your Project, Select the Target you are Profiling.
Build Settings -> Code Signing -> Code Signing Identity -> Release
Select your iOS developer profile.
Provisioning Profile: Let Xcode pick the correct Provisioning Profile for yo...
How to create a drop-down list?
...eated one.
dropdown.setAdapter(adapter);
Notes:
You can use a setOnItemSelectedListener with this.
You can add a strings list from xml
There is an appCompat version of this view.
More information:
This is the basics but there is more to be self taught with experimentation.
https://developer....
Get the new record primary key ID from MySQL insert query?
...
Eg:
INSERT INTO table_name (col1, col2,...) VALUES ('val1', 'val2'...);
SELECT LAST_INSERT_ID();
This will get you back the PRIMARY KEY value of the last row that you inserted:
The ID that was generated is maintained in the server on a per-connection basis. This means that the value returne...
How do I drop a foreign key constraint only if it exists in sql server?
...target a foreign key constraint on a specific table, use this:
IF EXISTS (SELECT *
FROM sys.foreign_keys
WHERE object_id = OBJECT_ID(N'dbo.FK_TableName_TableName2')
AND parent_object_id = OBJECT_ID(N'dbo.TableName')
)
ALTER TABLE [dbo.TableName] DROP CONSTRAINT [FK_TableName_TableName2]...
Ora-00257 错误处理一列 - 数据库(内核) - 清泛网 - 专注C/C++及内核技术
.../oracle/.bash_profile
进入ORLACE
sqlplus /as sysdba
SQL> select * from v$log;
GROUP# THREAD# SEQUENCE# BYTES BLOCKSIZE MEMBERS ARC
---------- ---------- ---------- ---------- ---------- ---------- ---
STATUS FIRST_CHANGE# FIRST_TIME NEXT_CHANGE#...
MySQL和MongoDB设计实例进行对比 - 大数据 & AI - 清泛网 - 专注C/C++及内核技术
...并且外观设计是直板的手机，需按照如下方式查询：
SELECT * FROM `mobile_params` WHERE name = '待机时间' AND value > 100;
SELECT * FROM `mobile_params` WHERE name = '外观设计' AND value = '直板';
注：参数表为了方便，把数值和字符串统一保存成字...
The name 'InitializeComponent' does not exist in the current context
If I create a new project in Visual Studio 2010 SP1 and select "WPF Application" and tries to build the generated application, I get the error
...