How to find all variables of an expression?
Is there a function that can extract a list of variables in an expression?
For example, assume we have an expression
x^2+y^3+z
This expression has variables x, y and z. The result should be
{x, y, z}
. Is there a way to get this?
expression-manipulation
asked Dec 18 at 9:06
haoshu li
261
add a comment |
Is there a function that can extract a list of variables in an expression?
For example, assume we have an expression
x^2+y^3+z
This expression has variables x, y and z. The result should be
{x, y, z}
. Is there a way to get this?
expression-manipulation
asked Dec 18 at 9:06
haoshu li
261
9
Variablescommand should workVariables[x^2 + y^3 + z]
– Buddha_the_Scientist
Dec 18 at 9:07
add a comment |
Is there a function that can extract a list of variables in an expression?
For example, assume we have an expression
x^2+y^3+z
This expression has variables x, y and z. The result should be
{x, y, z}
. Is there a way to get this?
expression-manipulation
asked Dec 18 at 9:06
haoshu li
261
Is there a function that can extract a list of variables in an expression?
For example, assume we have an expression
x^2+y^3+z
This expression has variables x, y and z. The result should be
{x, y, z}
. Is there a way to get this?
expression-manipulation
expression-manipulation
asked Dec 18 at 9:06
haoshu li
261
asked Dec 18 at 9:06
haoshu li
261
asked Dec 18 at 9:06
haoshu li
261
asked Dec 18 at 9:06
haoshu li
261
asked Dec 18 at 9:06
haoshu li
261
261
9
Variablescommand should workVariables[x^2 + y^3 + z]
– Buddha_the_Scientist
Dec 18 at 9:07
add a comment |
9
Variablescommand should workVariables[x^2 + y^3 + z]
– Buddha_the_Scientist
Dec 18 at 9:07
9
9
Variables command should work Variables[x^2 + y^3 + z]– Buddha_the_Scientist
Dec 18 at 9:07
Variables command should work Variables[x^2 + y^3 + z]– Buddha_the_Scientist
Dec 18 at 9:07
add a comment |
2 Answers
2
active
oldest
votes
For polynomial expressions @Buddha_the_Scientist's suggestion Variables will work. For more general expressions
expr = x^2 + y^3 + z
DeleteDuplicates@Cases[expr, _Symbol, ∞]
Should do the trick in most situations.
edited Dec 18 at 16:29
Henrik Schumacher
48.7k467139
answered Dec 18 at 9:36
mmeent
2,099614
Since all symbols are on level -1, you can use{-1}, instead of[infinity].
– Fred Simons
Dec 18 at 11:14
Might want to include only symbols in the"Global`"context. I'd probably useUnioninstead ofDeleteDuplicatesto get them in canonical order.
– Michael E2
Dec 18 at 16:37
add a comment |
I like the following approach x):
expr = x^2 + y^3 + z;
Select[DeleteDuplicates@Level[expr, Depth@expr], Head[#] == Symbol &]
the result is:
{x, y, z}
answered Dec 18 at 16:58
Xminer
526
add a comment |
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2 Answers
2
active
oldest
votes
2 Answers
2
active
oldest
votes
active
oldest
votes
active
oldest
votes
For polynomial expressions @Buddha_the_Scientist's suggestion Variables will work. For more general expressions
expr = x^2 + y^3 + z
DeleteDuplicates@Cases[expr, _Symbol, ∞]
Should do the trick in most situations.
edited Dec 18 at 16:29
Henrik Schumacher
48.7k467139
answered Dec 18 at 9:36
mmeent
2,099614
Since all symbols are on level -1, you can use{-1}, instead of[infinity].
– Fred Simons
Dec 18 at 11:14
Might want to include only symbols in the"Global`"context. I'd probably useUnioninstead ofDeleteDuplicatesto get them in canonical order.
– Michael E2
Dec 18 at 16:37
add a comment |
For polynomial expressions @Buddha_the_Scientist's suggestion Variables will work. For more general expressions
expr = x^2 + y^3 + z
DeleteDuplicates@Cases[expr, _Symbol, ∞]
Should do the trick in most situations.
edited Dec 18 at 16:29
Henrik Schumacher
48.7k467139
answered Dec 18 at 9:36
mmeent
2,099614
Since all symbols are on level -1, you can use{-1}, instead of[infinity].
– Fred Simons
Dec 18 at 11:14
Might want to include only symbols in the"Global`"context. I'd probably useUnioninstead ofDeleteDuplicatesto get them in canonical order.
– Michael E2
Dec 18 at 16:37
add a comment |
For polynomial expressions @Buddha_the_Scientist's suggestion Variables will work. For more general expressions
expr = x^2 + y^3 + z
DeleteDuplicates@Cases[expr, _Symbol, ∞]
Should do the trick in most situations.
edited Dec 18 at 16:29
Henrik Schumacher
48.7k467139
answered Dec 18 at 9:36
mmeent
2,099614
For polynomial expressions @Buddha_the_Scientist's suggestion Variables will work. For more general expressions
expr = x^2 + y^3 + z
DeleteDuplicates@Cases[expr, _Symbol, ∞]
Should do the trick in most situations.
edited Dec 18 at 16:29
Henrik Schumacher
48.7k467139
answered Dec 18 at 9:36
mmeent
2,099614
edited Dec 18 at 16:29
Henrik Schumacher
48.7k467139
edited Dec 18 at 16:29
Henrik Schumacher
48.7k467139
edited Dec 18 at 16:29
Henrik Schumacher
48.7k467139
48.7k467139
answered Dec 18 at 9:36
mmeent
2,099614
answered Dec 18 at 9:36
mmeent
2,099614
answered Dec 18 at 9:36
mmeent
2,099614
2,099614
Since all symbols are on level -1, you can use{-1}, instead of[infinity].
– Fred Simons
Dec 18 at 11:14
Might want to include only symbols in the"Global`"context. I'd probably useUnioninstead ofDeleteDuplicatesto get them in canonical order.
– Michael E2
Dec 18 at 16:37
add a comment |
Since all symbols are on level -1, you can use{-1}, instead of[infinity].
– Fred Simons
Dec 18 at 11:14
Might want to include only symbols in the"Global`"context. I'd probably useUnioninstead ofDeleteDuplicatesto get them in canonical order.
– Michael E2
Dec 18 at 16:37
Since all symbols are on level -1, you can use
{-1} , instead of [infinity].– Fred Simons
Dec 18 at 11:14
Since all symbols are on level -1, you can use
{-1} , instead of [infinity].– Fred Simons
Dec 18 at 11:14
Might want to include only symbols in the
"Global`" context. I'd probably use Union instead of DeleteDuplicates to get them in canonical order.– Michael E2
Dec 18 at 16:37
Might want to include only symbols in the
"Global`" context. I'd probably use Union instead of DeleteDuplicates to get them in canonical order.– Michael E2
Dec 18 at 16:37
add a comment |
I like the following approach x):
expr = x^2 + y^3 + z;
Select[DeleteDuplicates@Level[expr, Depth@expr], Head[#] == Symbol &]
the result is:
{x, y, z}
answered Dec 18 at 16:58
Xminer
526
add a comment |
I like the following approach x):
expr = x^2 + y^3 + z;
Select[DeleteDuplicates@Level[expr, Depth@expr], Head[#] == Symbol &]
the result is:
{x, y, z}
answered Dec 18 at 16:58
Xminer
526
add a comment |
I like the following approach x):
expr = x^2 + y^3 + z;
Select[DeleteDuplicates@Level[expr, Depth@expr], Head[#] == Symbol &]
the result is:
{x, y, z}
answered Dec 18 at 16:58
Xminer
526
I like the following approach x):
expr = x^2 + y^3 + z;
Select[DeleteDuplicates@Level[expr, Depth@expr], Head[#] == Symbol &]
the result is:
{x, y, z}
answered Dec 18 at 16:58
Xminer
526
answered Dec 18 at 16:58
Xminer
526
answered Dec 18 at 16:58
Xminer
526
answered Dec 18 at 16:58
Xminer
526
526
add a comment |
add a comment |
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9
Variablescommand should workVariables[x^2 + y^3 + z]– Buddha_the_Scientist
Dec 18 at 9:07