小编Sau*_*abh的帖子

我正在尝试将图像文件转换为bas64，因此我可以将base64字符串形式存储在mongoDB中。

这就是我试图做到的方式：

router.post('/file_upload',function(req,res){

  function base64_encode(file) {
    var bitmap = fs.readFileSync(file);
    return new Buffer(bitmap).toString('base64');
}

  var ImageFileToSave =  base64_encode(req.body.file);

  console.log(ImageFileToSave);


})

在客户端：

<form action="/file_upload" method="POST" enctype="multipart/form-
 data">
<input type="file" name="file" />
<input type="submit" value="Upload File" />
</form>

这是我得到的错误

TypeError：路径必须是字符串或Buffer

如何将图像文件（例如：image.jpg）转换为base64？

当我在函数中传递以下字符串作为参数时,如何获得以下输出？

• 输入: "Reverse this line"

• 输出: "esreveR siht enil"

这是我的代码

function reverseWords(string) {
    var wordArray = string.split(" ");
    var resultWordArray = [];
    var requiredSentance;
    wordArray.forEach(word => {
        if (word == " ") {
            var space = " ";
            resultWordArray.push(space);
        } else {
            var SplittedWord = word.split("");
            var reversedWordsLettersArray = [];
            SplittedWord.forEach(letter => {
                reversedWordsLettersArray.unshift(letter);
                var reversedWord = reversedWordsLettersArray.join("");
                resultWordArray.push(reversedWord);
            })
        }
    })
    var resultSentance = resultWordArray.join(" ");
    console.log(resultSentance);
}
reverseWords("Reverse this line");

这将作为输出返回:

"R eR veR eveR reveR sreveR esreveR …

我真的是机器学习的新手，我正在研究sklearn上的一些示例

有人可以在以下示例中解释“随机状态”的真正含义吗

import numpy as np
from sklearn.model_selection import train_test_split
X, y = np.arange(10).reshape((5, 2)), range(5)
X

list(y)


X_train, X_test, y_train, y_test = train_test_split(
    X, y, test_size=0.33, random_state=42) 

X_train

y_train

X_test

y_test

为什么将其硬编码为42？

如何在同一查询中使用where和group by 之间的位置

  SELECT `sales-store-id`,
  (SUM (`gen-acute-sales-after-returns`) + SUM(`gen- chronic-sales-after-returns`)) 
   AS `totalGenericSales` ,
  (SUM (`eth-acute-sales- after-returns`) + SUM(`eth-chronic-sales-after-returns`) + SUM(`others-sales- 
after-returns`))
 AS `totalEthicalSales` 
 FROM `sales` GROUP BY `sales-store-id` 
WHERE `date-s` BETWEEN '2018-09-01' AND '2018-10-01'

这是给出SQL错误,所以我尝试了AND而不是WHERE 但是这也没有正确地分组结果它只给出2个具有相同id的结果

   SELECT `sales-store-id`,
      (SUM (`gen-acute-sales-after-returns`) + SUM(`gen- chronic-sales-after-returns`)) 
       AS `totalGenericSales` ,
      (SUM (`eth-acute-sales- after-returns`) + SUM(`eth-chronic-sales-after-returns`) + SUM(`others-sales- 
    after-returns`))
     AS `totalEthicalSales` 
     FROM `sales` GROUP BY `sales-store-id` 
    AND `date-s` BETWEEN '2018-09-01' AND '2018-10-01'

我在这里失踪了什么？