代写Investment Modeling Spring 2019, Practice Set # 4代做留学生Matlab编程
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Use the code below to answer questions # 1-5.
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library (data .table) M3=data .frame (x=1:5,y=seq (2,10,2),z=7:3) setDT(M3) |
1. What is sum(M3[,3])?
2. What is sum(M3[,2])?
3. What is sum(M3+rep(2,5))?
4. What is M3[y¡6,x]?
5. What is sum(M3[,2]+M3[,x])?
Use the code below to answer questions # 6-7.
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giants=c (2:5) cowboys=rep (3,4) eagles=c (6: giants[cowboys [2]]) |
6. What is x?
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x= sum ( sum (giants)*eagles) |
7. What is x?
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x= sum (giants + c (eagles , cowboys[giants [1]])) |
8. What is a?
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a = 6:1 a[c (2,4)]= c (10,20) |
9. What is a?
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a = 6:1 a[2:4]=rep (2,3) |
10. What is mm?
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mm = c (1:9) mm[2:4]= c (12,13,14) |
11. What is mm?
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mm = c (1:9) mm[c (7,3:2)]= c (20,40,60) |
12. Given the code below, what is a?
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z = 3:1 a=0 for (i in z) { a=a-i } |
13. Given the code below, what is b?
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x = 1:4 b=c (2,4,6,8) for (i in x) { if ((i/2) >3) { b[NROW (b)]=i/2 } else { b[(i/2)+2*i]=i/2 } }
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Use the table mdf below to answer questions from #14-19.
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Ticker |
Date |
TotalAssets |
TotalDebt |
Price |
|
FB |
201703 |
150 |
30 |
4 |
|
FB |
201706 |
100 |
25 |
1 |
|
FB |
201709 |
500 |
100 |
3 |
|
FB |
201712 |
100 |
20 |
5 |
|
AAPL |
201703 |
200 |
100 |
2 |
|
AAPL |
201706 |
150 |
30 |
4 |
|
AAPL |
201709 |
300 |
15 |
6 |
|
AAPL |
201712 |
100 |
10 |
8 |
|
TSLA |
201703 |
250 |
50 |
4 |
|
TSLA |
201706 |
200 |
40 |
10 |
|
TSLA |
201709 |
350 |
70 |
6 |
|
TSLA |
201712 |
150 |
50 |
5 |
14. Given the code below, what is tt?
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z = 1:4 tt=head(mdf$Price ,5) r=seq (2,10,2) for (i in z) { for (x in r[c (1,3,5)]) { tt[NROW (r)]=i+x } } |
15. Given the code below, what is b?
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v = head(mdf$Price ,9) z = tail(v,5) b=c () for (i in z) { if ((i -1) >=3 && (i-4) <=3) { b[NROW (b)+1]=i } else { b=c (b,i) } } |
16. Given the code below, what is v?
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v = c (2,4,10,5,2,8,12) z=seq (2,12,mdf[Ticker== ’AAPL ’ & Date==201703, Price]) v[c (2:3,6)]=z[c (1,4:5)] |
17. Given the code below, what is v?
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stock=head(mdf ,4) stockc = stock[,Price] ret=c () for (i in 1:(NROW (stockc) -1)) { ret[i]=(stockc[i+1] + stockc[i]) - 1 } v=ret[1] |