Changing the elements of the list based on subscripts
$begingroup$
Say I have a list of lists:
{{Subscript[a,1],Subscript[a,1]+Subscript[a,2],Subscript[a,-3]},
{Subscript[a,1],Subscript[a,-2],Subscript[a,-4]}}
Now, in the sublists of that list, if an element has a negative subscript I want to change this element to a negative of that element with a positive subscript, so if I applied this to the list above I'd get:
{{Subscript[a,1],Subscript[a,1]+Subscript[a,2],-Subscript[a,3]},
{Subscript[a,1],-Subscript[a,2],-Subscript[a,4]}}
I don't really know how to do it. Any help would be much appreciated.
list-manipulation subscript
$endgroup$
add a comment |
$begingroup$
Say I have a list of lists:
{{Subscript[a,1],Subscript[a,1]+Subscript[a,2],Subscript[a,-3]},
{Subscript[a,1],Subscript[a,-2],Subscript[a,-4]}}
Now, in the sublists of that list, if an element has a negative subscript I want to change this element to a negative of that element with a positive subscript, so if I applied this to the list above I'd get:
{{Subscript[a,1],Subscript[a,1]+Subscript[a,2],-Subscript[a,3]},
{Subscript[a,1],-Subscript[a,2],-Subscript[a,4]}}
I don't really know how to do it. Any help would be much appreciated.
list-manipulation subscript
$endgroup$
add a comment |
$begingroup$
Say I have a list of lists:
{{Subscript[a,1],Subscript[a,1]+Subscript[a,2],Subscript[a,-3]},
{Subscript[a,1],Subscript[a,-2],Subscript[a,-4]}}
Now, in the sublists of that list, if an element has a negative subscript I want to change this element to a negative of that element with a positive subscript, so if I applied this to the list above I'd get:
{{Subscript[a,1],Subscript[a,1]+Subscript[a,2],-Subscript[a,3]},
{Subscript[a,1],-Subscript[a,2],-Subscript[a,4]}}
I don't really know how to do it. Any help would be much appreciated.
list-manipulation subscript
$endgroup$
Say I have a list of lists:
{{Subscript[a,1],Subscript[a,1]+Subscript[a,2],Subscript[a,-3]},
{Subscript[a,1],Subscript[a,-2],Subscript[a,-4]}}
Now, in the sublists of that list, if an element has a negative subscript I want to change this element to a negative of that element with a positive subscript, so if I applied this to the list above I'd get:
{{Subscript[a,1],Subscript[a,1]+Subscript[a,2],-Subscript[a,3]},
{Subscript[a,1],-Subscript[a,2],-Subscript[a,4]}}
I don't really know how to do it. Any help would be much appreciated.
list-manipulation subscript
list-manipulation subscript
asked 12 hours ago
amator2357amator2357
1117
1117
add a comment |
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1 Answer
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$begingroup$
You can use pattern matching for this:
expr = {{Subscript[a, 1], Subscript[a, 1] + Subscript[a, 2], Subscript[a, -3]}, {Subscript[a, 1], Subscript[a, -2], Subscript[a, -4]}}
expr /. Subscript[a, n_Integer /; n < 0] :> - Subscript[a, -n]
$endgroup$
$begingroup$
I was just looking at pattern matching :) Thank you very much @Fred Simons .
$endgroup$
– amator2357
12 hours ago
add a comment |
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1 Answer
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1 Answer
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active
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$begingroup$
You can use pattern matching for this:
expr = {{Subscript[a, 1], Subscript[a, 1] + Subscript[a, 2], Subscript[a, -3]}, {Subscript[a, 1], Subscript[a, -2], Subscript[a, -4]}}
expr /. Subscript[a, n_Integer /; n < 0] :> - Subscript[a, -n]
$endgroup$
$begingroup$
I was just looking at pattern matching :) Thank you very much @Fred Simons .
$endgroup$
– amator2357
12 hours ago
add a comment |
$begingroup$
You can use pattern matching for this:
expr = {{Subscript[a, 1], Subscript[a, 1] + Subscript[a, 2], Subscript[a, -3]}, {Subscript[a, 1], Subscript[a, -2], Subscript[a, -4]}}
expr /. Subscript[a, n_Integer /; n < 0] :> - Subscript[a, -n]
$endgroup$
$begingroup$
I was just looking at pattern matching :) Thank you very much @Fred Simons .
$endgroup$
– amator2357
12 hours ago
add a comment |
$begingroup$
You can use pattern matching for this:
expr = {{Subscript[a, 1], Subscript[a, 1] + Subscript[a, 2], Subscript[a, -3]}, {Subscript[a, 1], Subscript[a, -2], Subscript[a, -4]}}
expr /. Subscript[a, n_Integer /; n < 0] :> - Subscript[a, -n]
$endgroup$
You can use pattern matching for this:
expr = {{Subscript[a, 1], Subscript[a, 1] + Subscript[a, 2], Subscript[a, -3]}, {Subscript[a, 1], Subscript[a, -2], Subscript[a, -4]}}
expr /. Subscript[a, n_Integer /; n < 0] :> - Subscript[a, -n]
answered 12 hours ago
Fred SimonsFred Simons
7,1671241
7,1671241
$begingroup$
I was just looking at pattern matching :) Thank you very much @Fred Simons .
$endgroup$
– amator2357
12 hours ago
add a comment |
$begingroup$
I was just looking at pattern matching :) Thank you very much @Fred Simons .
$endgroup$
– amator2357
12 hours ago
$begingroup$
I was just looking at pattern matching :) Thank you very much @Fred Simons .
$endgroup$
– amator2357
12 hours ago
$begingroup$
I was just looking at pattern matching :) Thank you very much @Fred Simons .
$endgroup$
– amator2357
12 hours ago
add a comment |
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