小编Gen*_* Xu的帖子

我想使用嵌套 CV 方法从 SVC 中找到最佳参数：

import numpy as np
import pandas as pd
import matplotlib.pyplot as plt
%matplotlib inline

from sklearn.datasets import load_breast_cancer
cancer = load_breast_cancer()
X, y = load_breast_cancer(return_X_y=True)

from sklearn.model_selection import train_test_split
X_train, X_test, y_train, y_test = train_test_split(X, y, test_size=0.30, random_state=42)

from sklearn.model_selection import GridSearchCV, cross_val_score
from sklearn.pipeline import make_pipeline
from sklearn.preprocessing import Imputer, StandardScaler
from sklearn.decomposition import PCA
from sklearn.svm import SVC

pipe_svc = make_pipeline(Imputer(),StandardScaler(),PCA(n_components=2),SVC(random_state=1))
param_range = [0.001,0.01,0.1,1,10,100,1000]
param_grid = [{'svc__C': param_range, 'svc__kernel': ['linear']},
              {'svc__C': param_range, 'svc__gamma': …

这种差异使我感到困惑:

>>> s = "()())()"
>>> print set(s)

set([')', '('])

>>> print {s}

set(['()())()'])

为什么？

我一直在尝试使用在线提示解决这个“销毁方法异常”，但没有成功。这是错误消息：

2017-10-16 15:58:13.234 错误 12276 --- [main] osbfsDefaultListableBeanFactory：销毁名为“org.springframework.boot.autoconfigure.internalCachingMetadataReaderFactory”的 bean 的方法引发异常

这是我的 POM.xml 依赖项：

<dependencies>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-actuator</artifactId>
    </dependency>
    <dependency>
        <groupId>org.springframework.cloud</groupId>
        <artifactId>spring-cloud-starter-aws</artifactId>
    </dependency>
    <dependency>
        <groupId>org.springframework.cloud</groupId>
        <artifactId>spring-cloud-starter-aws-jdbc</artifactId>
    </dependency>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-web</artifactId>
    </dependency>
    <dependency>
        <groupId>org.projectlombok</groupId>
        <artifactId>lombok</artifactId>
        <version>1.16.6</version>
        <scope>provided</scope>
    </dependency>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-data-jpa</artifactId>
    </dependency>
</dependencies>

从网上看来，问题出在 spring-boot-starter-data-jpa 依赖项上。我尝试了旧版本的依赖，并清理了 mvn，但它们都不起作用。

更新

从spring initializr重新生成pom后，我仍然遇到同样的错误。这是我的 pom.xml 依赖项：

    <dependencies>
<!--need this aws dependency for some packages-->
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-aws</artifactId>
        </dependency>
<!--need this aws dependency for some packages-->
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-aws-jdbc</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId> …

我正在开发一个用于谷歌服务文本检测的应用程序,并遇到使用File_PROVIDER共享文件的问题.

AndroidManifest.xml中:

<manifest xmlns:android="http://schemas.android.com/apk/res/android"
      package="myPackageFoo">

<uses-feature android:name="android.hardware.camera" />

<uses-permission android:name="android.permission.CAMERA" />

<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />

<application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:theme="@style/AppTheme">
    <meta-data
            android:name="com.google.android.nearby.messages.API_KEY"
            android:value="@string/API_KEY" />
    <meta-data
            android:name="com.google.android.gms.vision.DEPENDENCIES"
            android:value="ocr" />
    <activity android:name=".MainActivity" android:screenOrientation="portrait">
        <intent-filter>
            <action android:name="android.intent.action.MAIN"/>

            <category android:name="android.intent.category.LAUNCHER"/>
        </intent-filter>
    </activity>
    <provider
            android:name="android.support.v4.content.FileProvider"
            android:authorities="myPackageFoo.fileprovider"
            android:exported="false"
            android:grantUriPermissions="true">
        <meta-data
                android:name="android.support.FILE_PROVIDER_PATHS"
                android:resource="@xml/provider_paths" />
    </provider>
</application>

对于res/xml/provider_paths.xml:

<paths>
<files-path path="images/" name="myimages" />
<external-path name="download" path="download/"/>
</paths>

但是我总是得到这个编译错误:

错误:找不到与给定名称匹配的资源(在'resource'处,值为'@ xml/provider_paths').

什么地方出了错？

说 y := []int

说 x := *[]int

问题1：是*x=y相当于x=&y？

我发现，当 y 更新时，比如说y=y[1:]，*x=y给了我正确的更新y，而x=&y仍然给了我旧的y.

问题二：为什么会这样？