每日一练 | Data Scientist & Business Analyst 面试题 144

大数据应用 · 公众号 · 大数据 · 2017-07-29 10:02

正文

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 44

DS Interview Questions

What is the goal of A/B Testing?

BA Interview Questions

R language:

You have the data.frame ‘mydf’ with four columns like below.

a = c(3,7,NA, 9)

b = c(2,NA,9,3)

f = c(5,2,5,6)

d = c(NA,3,4,NA)

mydf = data.frame(a=a,b=b,f=f,d=d)

mydf

## You want to add another column ‘5’:

## the 5th column contains the value of col b if col a is NA;

## the 5th column contains the value of col d if col b is NA;

## the 5th column contains the value of col f in all other cases.

欲知答案如何？请见下期分解！

Day 43 答案揭晓

DS Interview Questions

Give some classification situations where you will use an SVM over a RandomForest Machine Learning algorithm and vice-versa.

- When the data is outlier free and clean then go for SVM. If your data might contain outliers then Random forest would be the best choice.

- Generally, SVM consumes more computational power than Random Forest, so if you are constrained with memory go for Random Forest machine learning algorithm.

- Random Forest gives you a very good idea of variable importance in your data, so if you want to have variable importance then choose Random Forest machine learning algorithm.

- Random Forest machine learning algorithms are preferred for multiclass problems.

- SVM is preferred in multi-dimensional problem set - like text classification.

BA Interview Questions

R language:

Write a for loop that prints the Displacement (‘disp’) of the ‘mtcars’ dataset.

a. This loop will only print observations of 160 or higher in ‘disp’.

b. This loop will stop as soon as an observation is smaller than 160 in ‘disp’.

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。