每日一练 | Data Scientist & Business Analyst 面试题 140

从6月15日起，数据应用学院将与你一起温习数据科学（DS）和商业分析（BA）领域常见的面试问题。希望积极寻求相关领域工作的你每天关注我们的问题并且与我们一起思考，我们将会在第二天给出答案。

Day 40

DS Interview Questions

How to choose the parameter in gradient descent?

BA Interview Questions

R language: add up every elements in the matrix:

a <- matrix(c(0,2,0,2,1,2,2,0,2)

欲知答案如何？请见下期分解！

Day 39 答案揭晓

DS Interview Questions

Why is Manhattan distance not used in kNN machine learning algorithm to calculate the distance between nearest neighbours?

Manhattan distance has restrictions on dimensions and calculates the distance either vertically or horizontally. Euclidean distance is better option in kNN to calculate the distance between nearest neighbours because the data points can be represented in any space without any dimension restriction.

BA Interview Questions

What does UNION do? What is the difference between UNION and UNION ALL?

UNION merges the contents of two structurally-compatible tables into a single combined table. The difference between UNION and UNION ALL is that UNION will omit duplicate records whereas UNION ALL will include duplicate records.

It is important to note that the performance of UNION ALL will typically be better than UNION, since UNION requires the server to do the additional work of removing any duplicates. So, in cases where is is certain that there will not be any duplicates, or where having duplicates is not a problem, use of UNION ALL would be recommended for performance reasons.

12

数据应用学院

数据应用学院（Data Application Lab）, 北美第一家培训－项目实习－职业辅导－内推一站式专业数据人才输送机构，提供大数据和数据科学培训和公司项目解决方案，由南加州与硅谷的高级数据科学家与数据工程师联合创办，致力于传播数据行业最新应用和知识、培训及输送优秀大数据人才，以填补人才缺口、充分发挥大数据在商业中的力量。2016年被北美著名科技杂志Tech Beacon评为Top Data Camp。 

 长期招募 

TECHNICAL WRITER/翻译志愿者  

1. 职责：

1. 深度讨论数据应用

2. 调研行业发展

2. 要求：

1. 对数据应用极为感兴趣

2.  具备数据分析基础

3. 具有一定BUSINESS INSIGHT

4. 写作能力强

感兴趣的同学发送简历及writing sample到[e-mail]，邮件标题“申请翻译/Technical Writer”。

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