Extracting terms with certain heads in a function Planned maintenance scheduled April 17/18, 2019 at 00:00UTC (8:00pm US/Eastern) Announcing the arrival of Valued Associate #679: Cesar Manara Unicorn Meta Zoo #1: Why another podcast?Pattern matching list of elements with different headsWhy does the Derivative function not appear in the tree form?How to “invert” a ruleReplace Complex Head with ListHow to obtain a list of all build-in system level Heads?question about using Heads->True in Cases command
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Extracting terms with certain heads in a function
Planned maintenance scheduled April 17/18, 2019 at 00:00UTC (8:00pm US/Eastern)
Announcing the arrival of Valued Associate #679: Cesar Manara
Unicorn Meta Zoo #1: Why another podcast?Pattern matching list of elements with different headsWhy does the Derivative function not appear in the tree form?How to “invert” a ruleReplace Complex Head with ListHow to obtain a list of all build-in system level Heads?question about using Heads->True in Cases command
$begingroup$
Given a function with several arguments
func[a,b,g1[x],g1[x,y],g2[1],g2[g1[1]],3]
I would like to extract all arguments with the head g1 and g2 as a list. So the output I am looking for is
g1[x],g1[x,y],g2[1],g2[g1[1]]
The way I used to extract one head, say g1, is simply using the rule
/.func[l___,x__g1,r___]:> x
However, with two heads, this method does not work. I could write a module to do that but I wonder if there is a simpler way like the above rule for one head. Thank you so much!
head
asked 6 hours ago
mastrokmastrok
26917
$endgroup$
add a comment |
$begingroup$
Given a function with several arguments
func[a,b,g1[x],g1[x,y],g2[1],g2[g1[1]],3]
I would like to extract all arguments with the head g1 and g2 as a list. So the output I am looking for is
g1[x],g1[x,y],g2[1],g2[g1[1]]
The way I used to extract one head, say g1, is simply using the rule
/.func[l___,x__g1,r___]:> x
However, with two heads, this method does not work. I could write a module to do that but I wonder if there is a simpler way like the above rule for one head. Thank you so much!
head
asked 6 hours ago
mastrokmastrok
26917
$endgroup$
add a comment |
$begingroup$
Given a function with several arguments
func[a,b,g1[x],g1[x,y],g2[1],g2[g1[1]],3]
I would like to extract all arguments with the head g1 and g2 as a list. So the output I am looking for is
g1[x],g1[x,y],g2[1],g2[g1[1]]
The way I used to extract one head, say g1, is simply using the rule
/.func[l___,x__g1,r___]:> x
However, with two heads, this method does not work. I could write a module to do that but I wonder if there is a simpler way like the above rule for one head. Thank you so much!
head
asked 6 hours ago
mastrokmastrok
26917
$endgroup$
Given a function with several arguments
func[a,b,g1[x],g1[x,y],g2[1],g2[g1[1]],3]
I would like to extract all arguments with the head g1 and g2 as a list. So the output I am looking for is
g1[x],g1[x,y],g2[1],g2[g1[1]]
The way I used to extract one head, say g1, is simply using the rule
/.func[l___,x__g1,r___]:> x
However, with two heads, this method does not work. I could write a module to do that but I wonder if there is a simpler way like the above rule for one head. Thank you so much!
head
head
asked 6 hours ago
mastrokmastrok
26917
asked 6 hours ago
mastrokmastrok
26917
asked 6 hours ago
mastrokmastrok
26917
asked 6 hours ago
mastrokmastrok
26917
asked 6 hours ago
mastrokmastrok
26917
26917
add a comment |
add a comment |
2 Answers
2
active
oldest
votes
$begingroup$
Either
takeHeads = Cases[#, _g1 | _g2] &;
func[a, b, g1[x], g1[x, y], g2[1], g2[g1[1]], 3] // takeHeads
g1[x], g1[x, y], g2[1], g2[g1[1]]
or define func itself as
func = Cases[##, _g1 | _g2] &;
func[a, b, g1[x], g1[x, y], g2[1], g2[g1[1]], 3]
g1[x], g1[x, y], g2[1], g2[g1[1]]
edited 5 hours ago
march
17.6k22870
answered 6 hours ago
CoolwaterCoolwater
15.4k32553
$endgroup$
$begingroup$
thank you, the method using cases is very useful. I did not know that Cases works inside the functionfunc
$endgroup$
– mastrok
6 hours ago
2
$begingroup$
You could also use the 1-arg form ofCases, e.g.takeHeads = Cases[_g1 | _g2].
$endgroup$
– Carl Woll
4 hours ago
$begingroup$
@mastrok If that surprised you thatCasesworked on your customfuncexpression have a look at Everything is an Expression. Hope this helps to understand why this worked.
$endgroup$
– Thies Heidecke
4 hours ago
$begingroup$
@Thies Heidecke Yes, I know that everything is an expression. However I thought that Cases only works with List only but not a general head. Thanks!
$endgroup$
– mastrok
4 hours ago
add a comment |
$begingroup$
Select[##&@@func[a,b,g1[x],g1[x,y],g2[1],g2[g1[1]],3],h=#;Head@#==h&]&/@g1,g2
g1[x], g1[x, y], g2[1], g2[g1[1]]
answered 6 hours ago
J42161217J42161217
4,573324
$endgroup$
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
$begingroup$
Either
takeHeads = Cases[#, _g1 | _g2] &;
func[a, b, g1[x], g1[x, y], g2[1], g2[g1[1]], 3] // takeHeads
g1[x], g1[x, y], g2[1], g2[g1[1]]
or define func itself as
func = Cases[##, _g1 | _g2] &;
func[a, b, g1[x], g1[x, y], g2[1], g2[g1[1]], 3]
g1[x], g1[x, y], g2[1], g2[g1[1]]
edited 5 hours ago
march
17.6k22870
answered 6 hours ago
CoolwaterCoolwater
15.4k32553
$endgroup$
$begingroup$
thank you, the method using cases is very useful. I did not know that Cases works inside the functionfunc
$endgroup$
– mastrok
6 hours ago
2
$begingroup$
You could also use the 1-arg form ofCases, e.g.takeHeads = Cases[_g1 | _g2].
$endgroup$
– Carl Woll
4 hours ago
$begingroup$
@mastrok If that surprised you thatCasesworked on your customfuncexpression have a look at Everything is an Expression. Hope this helps to understand why this worked.
$endgroup$
– Thies Heidecke
4 hours ago
$begingroup$
@Thies Heidecke Yes, I know that everything is an expression. However I thought that Cases only works with List only but not a general head. Thanks!
$endgroup$
– mastrok
4 hours ago
add a comment |
$begingroup$
Either
takeHeads = Cases[#, _g1 | _g2] &;
func[a, b, g1[x], g1[x, y], g2[1], g2[g1[1]], 3] // takeHeads
g1[x], g1[x, y], g2[1], g2[g1[1]]
or define func itself as
func = Cases[##, _g1 | _g2] &;
func[a, b, g1[x], g1[x, y], g2[1], g2[g1[1]], 3]
g1[x], g1[x, y], g2[1], g2[g1[1]]
edited 5 hours ago
march
17.6k22870
answered 6 hours ago
CoolwaterCoolwater
15.4k32553
$endgroup$
$begingroup$
thank you, the method using cases is very useful. I did not know that Cases works inside the functionfunc
$endgroup$
– mastrok
6 hours ago
2
$begingroup$
You could also use the 1-arg form ofCases, e.g.takeHeads = Cases[_g1 | _g2].
$endgroup$
– Carl Woll
4 hours ago
$begingroup$
@mastrok If that surprised you thatCasesworked on your customfuncexpression have a look at Everything is an Expression. Hope this helps to understand why this worked.
$endgroup$
– Thies Heidecke
4 hours ago
$begingroup$
@Thies Heidecke Yes, I know that everything is an expression. However I thought that Cases only works with List only but not a general head. Thanks!
$endgroup$
– mastrok
4 hours ago
add a comment |
$begingroup$
Either
takeHeads = Cases[#, _g1 | _g2] &;
func[a, b, g1[x], g1[x, y], g2[1], g2[g1[1]], 3] // takeHeads
g1[x], g1[x, y], g2[1], g2[g1[1]]
or define func itself as
func = Cases[##, _g1 | _g2] &;
func[a, b, g1[x], g1[x, y], g2[1], g2[g1[1]], 3]
g1[x], g1[x, y], g2[1], g2[g1[1]]
edited 5 hours ago
march
17.6k22870
answered 6 hours ago
CoolwaterCoolwater
15.4k32553
$endgroup$
Either
takeHeads = Cases[#, _g1 | _g2] &;
func[a, b, g1[x], g1[x, y], g2[1], g2[g1[1]], 3] // takeHeads
g1[x], g1[x, y], g2[1], g2[g1[1]]
or define func itself as
func = Cases[##, _g1 | _g2] &;
func[a, b, g1[x], g1[x, y], g2[1], g2[g1[1]], 3]
g1[x], g1[x, y], g2[1], g2[g1[1]]
edited 5 hours ago
march
17.6k22870
answered 6 hours ago
CoolwaterCoolwater
15.4k32553
edited 5 hours ago
march
17.6k22870
edited 5 hours ago
march
17.6k22870
edited 5 hours ago
march
17.6k22870
17.6k22870
answered 6 hours ago
CoolwaterCoolwater
15.4k32553
answered 6 hours ago
CoolwaterCoolwater
15.4k32553
answered 6 hours ago
CoolwaterCoolwater
15.4k32553
15.4k32553
$begingroup$
thank you, the method using cases is very useful. I did not know that Cases works inside the functionfunc
$endgroup$
– mastrok
6 hours ago
2
$begingroup$
You could also use the 1-arg form ofCases, e.g.takeHeads = Cases[_g1 | _g2].
$endgroup$
– Carl Woll
4 hours ago
$begingroup$
@mastrok If that surprised you thatCasesworked on your customfuncexpression have a look at Everything is an Expression. Hope this helps to understand why this worked.
$endgroup$
– Thies Heidecke
4 hours ago
$begingroup$
@Thies Heidecke Yes, I know that everything is an expression. However I thought that Cases only works with List only but not a general head. Thanks!
$endgroup$
– mastrok
4 hours ago
add a comment |
$begingroup$
thank you, the method using cases is very useful. I did not know that Cases works inside the functionfunc
$endgroup$
– mastrok
6 hours ago
2
$begingroup$
You could also use the 1-arg form ofCases, e.g.takeHeads = Cases[_g1 | _g2].
$endgroup$
– Carl Woll
4 hours ago
$begingroup$
@mastrok If that surprised you thatCasesworked on your customfuncexpression have a look at Everything is an Expression. Hope this helps to understand why this worked.
$endgroup$
– Thies Heidecke
4 hours ago
$begingroup$
@Thies Heidecke Yes, I know that everything is an expression. However I thought that Cases only works with List only but not a general head. Thanks!
$endgroup$
– mastrok
4 hours ago
$begingroup$
thank you, the method using cases is very useful. I did not know that Cases works inside the function
func$endgroup$
– mastrok
6 hours ago
$begingroup$
thank you, the method using cases is very useful. I did not know that Cases works inside the function
func$endgroup$
– mastrok
6 hours ago
2
2
$begingroup$
You could also use the 1-arg form of
Cases, e.g. takeHeads = Cases[_g1 | _g2].$endgroup$
– Carl Woll
4 hours ago
$begingroup$
You could also use the 1-arg form of
Cases, e.g. takeHeads = Cases[_g1 | _g2].$endgroup$
– Carl Woll
4 hours ago
$begingroup$
@mastrok If that surprised you that
Cases worked on your custom func expression have a look at Everything is an Expression. Hope this helps to understand why this worked.$endgroup$
– Thies Heidecke
4 hours ago
$begingroup$
@mastrok If that surprised you that
Cases worked on your custom func expression have a look at Everything is an Expression. Hope this helps to understand why this worked.$endgroup$
– Thies Heidecke
4 hours ago
$begingroup$
@Thies Heidecke Yes, I know that everything is an expression. However I thought that Cases only works with List only but not a general head. Thanks!
$endgroup$
– mastrok
4 hours ago
$begingroup$
@Thies Heidecke Yes, I know that everything is an expression. However I thought that Cases only works with List only but not a general head. Thanks!
$endgroup$
– mastrok
4 hours ago
add a comment |
$begingroup$
Select[##&@@func[a,b,g1[x],g1[x,y],g2[1],g2[g1[1]],3],h=#;Head@#==h&]&/@g1,g2
g1[x], g1[x, y], g2[1], g2[g1[1]]
answered 6 hours ago
J42161217J42161217
4,573324
$endgroup$
add a comment |
$begingroup$
Select[##&@@func[a,b,g1[x],g1[x,y],g2[1],g2[g1[1]],3],h=#;Head@#==h&]&/@g1,g2
g1[x], g1[x, y], g2[1], g2[g1[1]]
answered 6 hours ago
J42161217J42161217
4,573324
$endgroup$
add a comment |
$begingroup$
Select[##&@@func[a,b,g1[x],g1[x,y],g2[1],g2[g1[1]],3],h=#;Head@#==h&]&/@g1,g2
g1[x], g1[x, y], g2[1], g2[g1[1]]
answered 6 hours ago
J42161217J42161217
4,573324
$endgroup$
Select[##&@@func[a,b,g1[x],g1[x,y],g2[1],g2[g1[1]],3],h=#;Head@#==h&]&/@g1,g2
g1[x], g1[x, y], g2[1], g2[g1[1]]
answered 6 hours ago
J42161217J42161217
4,573324
answered 6 hours ago
J42161217J42161217
4,573324
answered 6 hours ago
J42161217J42161217
4,573324
answered 6 hours ago
J42161217J42161217
4,573324
4,573324
add a comment |
add a comment |
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