小编K.C*_*hen的帖子

如果我有两个清单

l1 = [ 'A', 'B' ]

l2 = [ 1, 2 ]

获得pandas数据框的最优雅方式是什么,如下所示:

+-----+-----+-----+
|     | l1  | l2  |
+-----+-----+-----+
|  0  | A   | 1   |
+-----+-----+-----+
|  1  | A   | 2   |
+-----+-----+-----+
|  2  | B   | 1   |
+-----+-----+-----+
|  3  | B   | 2   |
+-----+-----+-----+

注意,第一列是索引.

I found that mock object in Mockito would throw ClassNotFoundException when used in Spark. Here is a minimal example:

import org.apache.spark.{SparkConf, SparkContext}
import org.mockito.{Matchers, Mockito}
import org.scalatest.FlatSpec
import org.scalatest.mockito.MockitoSugar

trait MyTrait {
  def myMethod(a: Int): Int
}

class MyTraitTest extends FlatSpec with MockitoSugar {
  "Mock" should "work in Spark" in {
    val m = mock[MyTrait](Mockito.withSettings().serializable())
    Mockito.when(m.myMethod(Matchers.any())).thenReturn(1)

    val conf = new SparkConf().setAppName("testApp").setMaster("local")
    val sc = new SparkContext(conf)

    assert(sc.makeRDD(Seq(1, 2, 3)).map(m.myMethod).first() == 1)
  }
}

which would throw the following exception:

[info] …

作为tensorflow的初学者，我很好奇看到tensorflow的预先估算器（例如tf.estimator.LinearClassifier）定义的图形。

具有以下代码段：

import numpy as np
import tensorflow as tf

estimator = tf.estimator.LinearClassifier(    
    feature_columns=[tf.feature_column.numeric_column("x")],
    model_dir="stackoverflow_model"
)

input_fn = tf.estimator.inputs.numpy_input_fn(x={"x": np.arange(5)}, y=np.array([1] * 5), shuffle=True)

estimator.train(input_fn)

我可以LinearClassifier在张量板上看到完美定义的图：

但是，如果我什么都没有，则：

print(tf.get_default_graph().as_graph_def())

我只会得到：

versions {
  producer: 26
}

所以我的问题是：该图在哪里定义LinearClassifier，如何正确检查它using as_graph_def()？

谢谢！

最近我发现了由erase方法引起的unordered_set这种奇怪的行为.我提出下面的最小例子.

首先,我创建一个unordered_set.然后我擦除其中一个元素,比如法国.然后我用for循环擦除每个元素.执行时,它会出现段错误.但是,如果我评论删除法国部分,那么代码工作正常.

这个程序是用编译的g++ test.cpp --std=c++11.g ++的版本是4.9.1.

#include <iostream>
#include <string>
#include <unordered_set>

int main ()
{
  std::unordered_set<std::string> myset =
  {"USA","Canada","France","UK","Japan","Germany","Italy"};

  // erasing by key, causing segfault later; no segfault if commented out
  myset.erase ( "France" );                         

  std::cout << "myset contains:";
  for ( const std::string& x: myset ) { myset.erase(x); }

  // The problem persists for a regular for loop as well. 
  //for (  std::unordered_set<std::string>::iterator it = myset.begin(); it!=myset.end(); it++  ) { myset.erase(it); }

  std::cout << std::endl; …