Mapping a function f[xi_,xj_] over a list x1, …, xn with the i < j restrictionSelectively Mapping over elements in a ListWhy is MapIndexed better than mapping over a range?Mapping a function that assigns values to a list over a different listfunction over list with conditionMapping slots over listsMapping over a piecewise functionMapping a function with levelspec vs. Mapping over a flattened list
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Mapping a function f[xi_,xj_] over a list x1, …, xn with the i
Selectively Mapping over elements in a ListWhy is MapIndexed better than mapping over a range?Mapping a function that assigns values to a list over a different listfunction over list with conditionMapping slots over listsMapping over a piecewise functionMapping a function with levelspec vs. Mapping over a flattened list
.everyoneloves__top-leaderboard:empty,.everyoneloves__mid-leaderboard:empty,.everyoneloves__bot-mid-leaderboard:empty
margin-bottom:0;
.everyonelovesstackoverflowposition:absolute;height:1px;width:1px;opacity:0;top:0;left:0;pointer-events:none;
$begingroup$
I am often facing the situation where I have a list $...x_k...$ and where I want to compute:
$$
...f[x_i,x_j]...text with i<j
$$
Unfortunately, I have not been able to find an elegant solution for this problem. What I'm doing right now seems horrible to me (indirections etc...):
n = 4;
x = Table[RandomReal[], n]
0.547984, 0.601967, 0.000917483, 0.738287
Map[f[Apply[Sequence, x[[#]]]] &,
Flatten[Table[i, j, i, 1, n, j, i + 1, n], 1]]
f[0.547984, 0.601967], f[0.547984, 0.000917483], f[0.547984,
0.738287], f[0.601967, 0.000917483], f[0.601967, 0.738287], f[0.000917483, 0.738287]
(in real situation f is defined f[xi_,xj_]:= xi-xj for instance)
Question: what is a better (builtin?) solution?
list-manipulation programming
asked May 28 at 11:14
Picaud VincentPicaud Vincent
1,5827 silver badges18 bronze badges
$endgroup$
add a comment
|
$begingroup$
I am often facing the situation where I have a list $...x_k...$ and where I want to compute:
$$
...f[x_i,x_j]...text with i<j
$$
Unfortunately, I have not been able to find an elegant solution for this problem. What I'm doing right now seems horrible to me (indirections etc...):
n = 4;
x = Table[RandomReal[], n]
0.547984, 0.601967, 0.000917483, 0.738287
Map[f[Apply[Sequence, x[[#]]]] &,
Flatten[Table[i, j, i, 1, n, j, i + 1, n], 1]]
f[0.547984, 0.601967], f[0.547984, 0.000917483], f[0.547984,
0.738287], f[0.601967, 0.000917483], f[0.601967, 0.738287], f[0.000917483, 0.738287]
(in real situation f is defined f[xi_,xj_]:= xi-xj for instance)
Question: what is a better (builtin?) solution?
list-manipulation programming
asked May 28 at 11:14
Picaud VincentPicaud Vincent
1,5827 silver badges18 bronze badges
$endgroup$
add a comment
|
$begingroup$
I am often facing the situation where I have a list $...x_k...$ and where I want to compute:
$$
...f[x_i,x_j]...text with i<j
$$
Unfortunately, I have not been able to find an elegant solution for this problem. What I'm doing right now seems horrible to me (indirections etc...):
n = 4;
x = Table[RandomReal[], n]
0.547984, 0.601967, 0.000917483, 0.738287
Map[f[Apply[Sequence, x[[#]]]] &,
Flatten[Table[i, j, i, 1, n, j, i + 1, n], 1]]
f[0.547984, 0.601967], f[0.547984, 0.000917483], f[0.547984,
0.738287], f[0.601967, 0.000917483], f[0.601967, 0.738287], f[0.000917483, 0.738287]
(in real situation f is defined f[xi_,xj_]:= xi-xj for instance)
Question: what is a better (builtin?) solution?
list-manipulation programming
asked May 28 at 11:14
Picaud VincentPicaud Vincent
1,5827 silver badges18 bronze badges
$endgroup$
I am often facing the situation where I have a list $...x_k...$ and where I want to compute:
$$
...f[x_i,x_j]...text with i<j
$$
Unfortunately, I have not been able to find an elegant solution for this problem. What I'm doing right now seems horrible to me (indirections etc...):
n = 4;
x = Table[RandomReal[], n]
0.547984, 0.601967, 0.000917483, 0.738287
Map[f[Apply[Sequence, x[[#]]]] &,
Flatten[Table[i, j, i, 1, n, j, i + 1, n], 1]]
f[0.547984, 0.601967], f[0.547984, 0.000917483], f[0.547984,
0.738287], f[0.601967, 0.000917483], f[0.601967, 0.738287], f[0.000917483, 0.738287]
(in real situation f is defined f[xi_,xj_]:= xi-xj for instance)
Question: what is a better (builtin?) solution?
list-manipulation programming
list-manipulation programming
asked May 28 at 11:14
Picaud VincentPicaud Vincent
1,5827 silver badges18 bronze badges
asked May 28 at 11:14
Picaud VincentPicaud Vincent
1,5827 silver badges18 bronze badges
edited May 28 at 11:40
Picaud Vincent
asked May 28 at 11:14
Picaud VincentPicaud Vincent
1,5827 silver badges18 bronze badges
asked May 28 at 11:14
Picaud VincentPicaud Vincent
1,5827 silver badges18 bronze badges
asked May 28 at 11:14
Picaud VincentPicaud Vincent
1,5827 silver badges18 bronze badges
1,5827 silver badges18 bronze badges
add a comment
|
add a comment
|
1 Answer
1
active
oldest
votes
$begingroup$
Subsets[f @@ x, 2]
f[0.817389, 0.11142], f[0.817389, 0.789526], f[0.817389, 0.187803],
f[0.11142, 0.789526], f[0.11142, 0.187803], f[0.789526, 0.187803]
You can also use
f @@@ Subsets[x, 2]
Join @@ Table[f @@ x[[i, j]], i, 1, n, j, i + 1, n]
answered May 28 at 11:32
kglrkglr
221k10 gold badges251 silver badges509 bronze badges
$endgroup$
add a comment
|
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1 Answer
1
active
oldest
votes
1 Answer
1
active
oldest
votes
active
oldest
votes
active
oldest
votes
$begingroup$
Subsets[f @@ x, 2]
f[0.817389, 0.11142], f[0.817389, 0.789526], f[0.817389, 0.187803],
f[0.11142, 0.789526], f[0.11142, 0.187803], f[0.789526, 0.187803]
You can also use
f @@@ Subsets[x, 2]
Join @@ Table[f @@ x[[i, j]], i, 1, n, j, i + 1, n]
answered May 28 at 11:32
kglrkglr
221k10 gold badges251 silver badges509 bronze badges
$endgroup$
add a comment
|
$begingroup$
Subsets[f @@ x, 2]
f[0.817389, 0.11142], f[0.817389, 0.789526], f[0.817389, 0.187803],
f[0.11142, 0.789526], f[0.11142, 0.187803], f[0.789526, 0.187803]
You can also use
f @@@ Subsets[x, 2]
Join @@ Table[f @@ x[[i, j]], i, 1, n, j, i + 1, n]
answered May 28 at 11:32
kglrkglr
221k10 gold badges251 silver badges509 bronze badges
$endgroup$
add a comment
|
$begingroup$
Subsets[f @@ x, 2]
f[0.817389, 0.11142], f[0.817389, 0.789526], f[0.817389, 0.187803],
f[0.11142, 0.789526], f[0.11142, 0.187803], f[0.789526, 0.187803]
You can also use
f @@@ Subsets[x, 2]
Join @@ Table[f @@ x[[i, j]], i, 1, n, j, i + 1, n]
answered May 28 at 11:32
kglrkglr
221k10 gold badges251 silver badges509 bronze badges
$endgroup$
Subsets[f @@ x, 2]
f[0.817389, 0.11142], f[0.817389, 0.789526], f[0.817389, 0.187803],
f[0.11142, 0.789526], f[0.11142, 0.187803], f[0.789526, 0.187803]
You can also use
f @@@ Subsets[x, 2]
Join @@ Table[f @@ x[[i, j]], i, 1, n, j, i + 1, n]
answered May 28 at 11:32
kglrkglr
221k10 gold badges251 silver badges509 bronze badges
edited May 28 at 11:37
answered May 28 at 11:32
kglrkglr
221k10 gold badges251 silver badges509 bronze badges
answered May 28 at 11:32
kglrkglr
221k10 gold badges251 silver badges509 bronze badges
answered May 28 at 11:32
kglrkglr
221k10 gold badges251 silver badges509 bronze badges
221k10 gold badges251 silver badges509 bronze badges
add a comment
|
add a comment
|
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