Investment Modeling Spring 2019, Practice Set # 4
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)
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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]])
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6. What is x?
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x= sum ( sum (giants)*eagles)
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7. What is x?
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x= sum (giants + c (eagles , cowboys[giants [1]]))
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8. What is a?
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a = 6:1
a[c (2,4)]= c (10,20)
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9. What is a?
10. What is mm?
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mm = c (1:9)
mm[2:4]= c (12,13,14)
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11. What is mm?
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mm = c (1:9)
mm[c (7,3:2)]= c (20,40,60)
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12. Given the code below, what is a?
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z = 3:1
a=0
for (i in z)
{
a=a-i
}
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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
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Date
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TotalAssets
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TotalDebt
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Price
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FB
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201703
|
150
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30
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4
|
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FB
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201706
|
100
|
25
|
1
|
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FB
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201709
|
500
|
100
|
3
|
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FB
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201712
|
100
|
20
|
5
|
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AAPL
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201703
|
200
|
100
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2
|
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AAPL
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201706
|
150
|
30
|
4
|
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AAPL
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201709
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300
|
15
|
6
|
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AAPL
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201712
|
100
|
10
|
8
|
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TSLA
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201703
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250
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50
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4
|
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TSLA
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201706
|
200
|
40
|
10
|
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TSLA
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201709
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350
|
70
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6
|
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TSLA
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201712
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150
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50
|
5
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14. Given the code below, what is tt?
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z = 1:4
tt=head(mdf$Price ,5)
r=seq (2,10,2)
for (i in z)
{
for (x in r[c (1,3,5)])
{
tt[NROW (r)]=i+x
}
}
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15. Given the code below, what is b?
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v = head(mdf$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)
}
}
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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)]
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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]
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