Applying a recursive function to a list to get another list

up vote
2
down vote

favorite

Here is code:

x2=1539.91, 5.05, -2.82, 0, 19, 135.93, 117.78, 11.61, 8.17, 13.76, 
1.5, 36.75, 137.77, -16.18, 4.18, -2.82, 0, 18.42, 53.19, 5.91, 
-16.18, 3.24, -2.82, 0, 53.19, 518.6, -16.18, 1.61, -2.82, 23, 0, 
70.92, 58.89, 13.08, 42.32, 57.67, -15.32, 1.76, -2.68, 18.42, 0, 
53.19, 6.33, -15.32, 2.01, -2.68, 0, 53.19, -15.32, 2.17, -2.68, 0,
-1000, 76.83, 27.18, 0.02, 8.88, 13.08, 30, 48.72, 16.02, -15.32, 
1.69, -2.68, 0, 0.7, 53.19, 1128.85, 11.49, 53.19, 16.61, 209.84,
1243.2, 23, 1.08

I want to create a new list called balancelist using a recursive function (or any other way so I learn) such that I end up with a list with something like this:

1539.91,1539.91-5.05,1539.91-5.05-(-2.82),......

I have tried the following code but it doesn't work:

balancefinal = 
For[i = 1, i <= Length[x2], i++, x2[[i]] - x2[[i + 1]]; 
Append[balancefinal]]

edited 13 mins ago

kglr

169k8192395

asked 1 hour ago

beemen

462

add a commentÂ |Â

up vote
2
down vote

favorite

Here is code:

x2=1539.91, 5.05, -2.82, 0, 19, 135.93, 117.78, 11.61, 8.17, 13.76, 
1.5, 36.75, 137.77, -16.18, 4.18, -2.82, 0, 18.42, 53.19, 5.91, 
-16.18, 3.24, -2.82, 0, 53.19, 518.6, -16.18, 1.61, -2.82, 23, 0, 
70.92, 58.89, 13.08, 42.32, 57.67, -15.32, 1.76, -2.68, 18.42, 0, 
53.19, 6.33, -15.32, 2.01, -2.68, 0, 53.19, -15.32, 2.17, -2.68, 0,
-1000, 76.83, 27.18, 0.02, 8.88, 13.08, 30, 48.72, 16.02, -15.32, 
1.69, -2.68, 0, 0.7, 53.19, 1128.85, 11.49, 53.19, 16.61, 209.84,
1243.2, 23, 1.08

I want to create a new list called balancelist using a recursive function (or any other way so I learn) such that I end up with a list with something like this:

1539.91,1539.91-5.05,1539.91-5.05-(-2.82),......

I have tried the following code but it doesn't work:

balancefinal = 
For[i = 1, i <= Length[x2], i++, x2[[i]] - x2[[i + 1]]; 
Append[balancefinal]]

edited 13 mins ago

kglr

169k8192395

asked 1 hour ago

beemen

462

add a commentÂ |Â

up vote
2
down vote

favorite

Here is code:

x2=1539.91, 5.05, -2.82, 0, 19, 135.93, 117.78, 11.61, 8.17, 13.76, 
1.5, 36.75, 137.77, -16.18, 4.18, -2.82, 0, 18.42, 53.19, 5.91, 
-16.18, 3.24, -2.82, 0, 53.19, 518.6, -16.18, 1.61, -2.82, 23, 0, 
70.92, 58.89, 13.08, 42.32, 57.67, -15.32, 1.76, -2.68, 18.42, 0, 
53.19, 6.33, -15.32, 2.01, -2.68, 0, 53.19, -15.32, 2.17, -2.68, 0,
-1000, 76.83, 27.18, 0.02, 8.88, 13.08, 30, 48.72, 16.02, -15.32, 
1.69, -2.68, 0, 0.7, 53.19, 1128.85, 11.49, 53.19, 16.61, 209.84,
1243.2, 23, 1.08

I want to create a new list called balancelist using a recursive function (or any other way so I learn) such that I end up with a list with something like this:

1539.91,1539.91-5.05,1539.91-5.05-(-2.82),......

I have tried the following code but it doesn't work:

balancefinal = 
For[i = 1, i <= Length[x2], i++, x2[[i]] - x2[[i + 1]]; 
Append[balancefinal]]

edited 13 mins ago

kglr

169k8192395

asked 1 hour ago

beemen

462

Here is code:

x2=1539.91, 5.05, -2.82, 0, 19, 135.93, 117.78, 11.61, 8.17, 13.76, 
1.5, 36.75, 137.77, -16.18, 4.18, -2.82, 0, 18.42, 53.19, 5.91, 
-16.18, 3.24, -2.82, 0, 53.19, 518.6, -16.18, 1.61, -2.82, 23, 0, 
70.92, 58.89, 13.08, 42.32, 57.67, -15.32, 1.76, -2.68, 18.42, 0, 
53.19, 6.33, -15.32, 2.01, -2.68, 0, 53.19, -15.32, 2.17, -2.68, 0,
-1000, 76.83, 27.18, 0.02, 8.88, 13.08, 30, 48.72, 16.02, -15.32, 
1.69, -2.68, 0, 0.7, 53.19, 1128.85, 11.49, 53.19, 16.61, 209.84,
1243.2, 23, 1.08

I want to create a new list called balancelist using a recursive function (or any other way so I learn) such that I end up with a list with something like this:

1539.91,1539.91-5.05,1539.91-5.05-(-2.82),......

I have tried the following code but it doesn't work:

balancefinal = 
For[i = 1, i <= Length[x2], i++, x2[[i]] - x2[[i + 1]]; 
Append[balancefinal]]

webmathematica mathematica-online

edited 13 mins ago

kglr

169k8192395

asked 1 hour ago

beemen

462

edited 13 mins ago

kglr

169k8192395

asked 1 hour ago

beemen

462

edited 13 mins ago

kglr

169k8192395

edited 13 mins ago

kglr

169k8192395

edited 13 mins ago

kglr

169k8192395

asked 1 hour ago

beemen

462

asked 1 hour ago

beemen

462

asked 1 hour ago

beemen

462

add a commentÂ |Â

2 Answers
2

active

oldest

votes

up vote
7
down vote

If you consider Accumulate a recursive function, then you could do:

2 x2[[1]] - Accumulate[x2]

This is much faster than using something like FoldList. For example:

x2 = RandomReal[-10, 10, 10^6];

r1 = 2 x2[[1]] - Accumulate[x2]; //AbsoluteTiming
r2 = FoldList[Subtract, x2]; //AbsoluteTiming

MinMax[r1 - r2]

0.005461, Null

0.161103, Null

-3.86535*10^-12, 1.65983*10^-11

answered 1 hour ago

Carl Woll

63.4k282163

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up vote
4
down vote

You can Fold Subtract on x2:

FoldList[Subtract, x2]

1539.91,1534.86,1537.68,1537.68,1518.68,1382.75,1264.97,1253.36,1245.19,1231.43,1229.93,1193.18,1055.41,1071.59,1067.41,1070.23,1070.23,1051.81,998.62,992.71,1008.89,1005.65,1008.47,1008.47,955.28,436.68,452.86,451.25,454.07,431.07,431.07,360.15,301.26,288.18,245.86,188.19,203.51,201.75,204.43,186.01,186.01,132.82,126.49,141.81,139.8,142.48,142.48,89.29,104.61,102.44,105.12,105.12,1105.12,1028.29,1001.11,1001.09,992.21,979.13,949.13,900.41,884.39,899.71,898.02,900.7,900.7,900.,846.81,-282.04,-293.53,-346.72,-363.33,-573.17,-1816.37,-1839.37,-1840.45

If you have to use For here is a modification of your code that gives the correct result:

balancefinal = x2[[1]];
For[i = 1, i < Length[x2], i++, AppendTo[balancefinal, balancefinal[[-1]] - x2[[i + 1]]]]

balancefinal == FoldList[Subtract, x2]

True

edited 6 mins ago

answered 1 hour ago

kglr

169k8192395

add a commentÂ |Â

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2 Answers
2

active

oldest

votes

2 Answers
2

active

oldest

votes

up vote
7
down vote

If you consider Accumulate a recursive function, then you could do:

2 x2[[1]] - Accumulate[x2]

This is much faster than using something like FoldList. For example:

x2 = RandomReal[-10, 10, 10^6];

r1 = 2 x2[[1]] - Accumulate[x2]; //AbsoluteTiming
r2 = FoldList[Subtract, x2]; //AbsoluteTiming

MinMax[r1 - r2]

0.005461, Null

0.161103, Null

-3.86535*10^-12, 1.65983*10^-11

answered 1 hour ago

Carl Woll

63.4k282163

add a commentÂ |Â

up vote
7
down vote

If you consider Accumulate a recursive function, then you could do:

2 x2[[1]] - Accumulate[x2]

This is much faster than using something like FoldList. For example:

x2 = RandomReal[-10, 10, 10^6];

r1 = 2 x2[[1]] - Accumulate[x2]; //AbsoluteTiming
r2 = FoldList[Subtract, x2]; //AbsoluteTiming

MinMax[r1 - r2]

0.005461, Null

0.161103, Null

-3.86535*10^-12, 1.65983*10^-11

answered 1 hour ago

Carl Woll

63.4k282163

add a commentÂ |Â

up vote
7
down vote

If you consider Accumulate a recursive function, then you could do:

2 x2[[1]] - Accumulate[x2]

This is much faster than using something like FoldList. For example:

x2 = RandomReal[-10, 10, 10^6];

r1 = 2 x2[[1]] - Accumulate[x2]; //AbsoluteTiming
r2 = FoldList[Subtract, x2]; //AbsoluteTiming

MinMax[r1 - r2]

0.005461, Null

0.161103, Null

-3.86535*10^-12, 1.65983*10^-11

answered 1 hour ago

Carl Woll

63.4k282163

If you consider Accumulate a recursive function, then you could do:

2 x2[[1]] - Accumulate[x2]

This is much faster than using something like FoldList. For example:

x2 = RandomReal[-10, 10, 10^6];

r1 = 2 x2[[1]] - Accumulate[x2]; //AbsoluteTiming
r2 = FoldList[Subtract, x2]; //AbsoluteTiming

MinMax[r1 - r2]

0.005461, Null

0.161103, Null

-3.86535*10^-12, 1.65983*10^-11

answered 1 hour ago

Carl Woll

63.4k282163

answered 1 hour ago

Carl Woll

63.4k282163

answered 1 hour ago

Carl Woll

63.4k282163

answered 1 hour ago

Carl Woll

63.4k282163

add a commentÂ |Â

up vote
4
down vote

You can Fold Subtract on x2:

FoldList[Subtract, x2]

1539.91,1534.86,1537.68,1537.68,1518.68,1382.75,1264.97,1253.36,1245.19,1231.43,1229.93,1193.18,1055.41,1071.59,1067.41,1070.23,1070.23,1051.81,998.62,992.71,1008.89,1005.65,1008.47,1008.47,955.28,436.68,452.86,451.25,454.07,431.07,431.07,360.15,301.26,288.18,245.86,188.19,203.51,201.75,204.43,186.01,186.01,132.82,126.49,141.81,139.8,142.48,142.48,89.29,104.61,102.44,105.12,105.12,1105.12,1028.29,1001.11,1001.09,992.21,979.13,949.13,900.41,884.39,899.71,898.02,900.7,900.7,900.,846.81,-282.04,-293.53,-346.72,-363.33,-573.17,-1816.37,-1839.37,-1840.45

If you have to use For here is a modification of your code that gives the correct result:

balancefinal = x2[[1]];
For[i = 1, i < Length[x2], i++, AppendTo[balancefinal, balancefinal[[-1]] - x2[[i + 1]]]]

balancefinal == FoldList[Subtract, x2]

True

edited 6 mins ago

answered 1 hour ago

kglr

169k8192395

add a commentÂ |Â

up vote
4
down vote

You can Fold Subtract on x2:

FoldList[Subtract, x2]

1539.91,1534.86,1537.68,1537.68,1518.68,1382.75,1264.97,1253.36,1245.19,1231.43,1229.93,1193.18,1055.41,1071.59,1067.41,1070.23,1070.23,1051.81,998.62,992.71,1008.89,1005.65,1008.47,1008.47,955.28,436.68,452.86,451.25,454.07,431.07,431.07,360.15,301.26,288.18,245.86,188.19,203.51,201.75,204.43,186.01,186.01,132.82,126.49,141.81,139.8,142.48,142.48,89.29,104.61,102.44,105.12,105.12,1105.12,1028.29,1001.11,1001.09,992.21,979.13,949.13,900.41,884.39,899.71,898.02,900.7,900.7,900.,846.81,-282.04,-293.53,-346.72,-363.33,-573.17,-1816.37,-1839.37,-1840.45

If you have to use For here is a modification of your code that gives the correct result:

balancefinal = x2[[1]];
For[i = 1, i < Length[x2], i++, AppendTo[balancefinal, balancefinal[[-1]] - x2[[i + 1]]]]

balancefinal == FoldList[Subtract, x2]

True

edited 6 mins ago

answered 1 hour ago

kglr

169k8192395

add a commentÂ |Â

up vote
4
down vote

You can Fold Subtract on x2:

FoldList[Subtract, x2]

1539.91,1534.86,1537.68,1537.68,1518.68,1382.75,1264.97,1253.36,1245.19,1231.43,1229.93,1193.18,1055.41,1071.59,1067.41,1070.23,1070.23,1051.81,998.62,992.71,1008.89,1005.65,1008.47,1008.47,955.28,436.68,452.86,451.25,454.07,431.07,431.07,360.15,301.26,288.18,245.86,188.19,203.51,201.75,204.43,186.01,186.01,132.82,126.49,141.81,139.8,142.48,142.48,89.29,104.61,102.44,105.12,105.12,1105.12,1028.29,1001.11,1001.09,992.21,979.13,949.13,900.41,884.39,899.71,898.02,900.7,900.7,900.,846.81,-282.04,-293.53,-346.72,-363.33,-573.17,-1816.37,-1839.37,-1840.45

If you have to use For here is a modification of your code that gives the correct result:

balancefinal = x2[[1]];
For[i = 1, i < Length[x2], i++, AppendTo[balancefinal, balancefinal[[-1]] - x2[[i + 1]]]]

balancefinal == FoldList[Subtract, x2]

True

edited 6 mins ago

answered 1 hour ago

kglr

169k8192395

You can Fold Subtract on x2:

FoldList[Subtract, x2]

1539.91,1534.86,1537.68,1537.68,1518.68,1382.75,1264.97,1253.36,1245.19,1231.43,1229.93,1193.18,1055.41,1071.59,1067.41,1070.23,1070.23,1051.81,998.62,992.71,1008.89,1005.65,1008.47,1008.47,955.28,436.68,452.86,451.25,454.07,431.07,431.07,360.15,301.26,288.18,245.86,188.19,203.51,201.75,204.43,186.01,186.01,132.82,126.49,141.81,139.8,142.48,142.48,89.29,104.61,102.44,105.12,105.12,1105.12,1028.29,1001.11,1001.09,992.21,979.13,949.13,900.41,884.39,899.71,898.02,900.7,900.7,900.,846.81,-282.04,-293.53,-346.72,-363.33,-573.17,-1816.37,-1839.37,-1840.45

If you have to use For here is a modification of your code that gives the correct result:

balancefinal = x2[[1]];
For[i = 1, i < Length[x2], i++, AppendTo[balancefinal, balancefinal[[-1]] - x2[[i + 1]]]]

balancefinal == FoldList[Subtract, x2]

True

edited 6 mins ago

answered 1 hour ago

kglr

169k8192395

edited 6 mins ago

answered 1 hour ago

kglr

169k8192395

answered 1 hour ago

kglr

169k8192395

answered 1 hour ago

kglr

169k8192395

add a commentÂ |Â

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