4 added 58 characters in body
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Select[#, #[[1]] == 1 &] & /@ all
Select[#[[1]] == 1 &] /@ all (* thanks: Mr.Wizard *)
Pick[all, #[[1]] == 1 & /@ # & /@ all]
Pick[all, all[[All, All, 1]], 1]
Map[If[#[[1]] == 1, #, ## &[]] &, all, {2}]

all give

{{{1, 2}, {1, 3}}, {{1, 1}, {1, 5}}}

Select[#, #[[1]] == 1 &] & /@ all
Pick[all, #[[1]] == 1 & /@ # & /@ all]
Pick[all, all[[All, All, 1]], 1]
Map[If[#[[1]] == 1, #, ## &[]] &, all, {2}]

all give

{{{1, 2}, {1, 3}}, {{1, 1}, {1, 5}}}

Select[#, #[[1]] == 1 &] & /@ all
Select[#[[1]] == 1 &] /@ all (* thanks: Mr.Wizard *)
Pick[all, #[[1]] == 1 & /@ # & /@ all]
Pick[all, all[[All, All, 1]], 1]
Map[If[#[[1]] == 1, #, ## &[]] &, all, {2}]

all give

{{{1, 2}, {1, 3}}, {{1, 1}, {1, 5}}}

3 added 2 characters in body
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Select[#, #[[1]] == 1 &] & /@ all

{{{1, 2}, {1, 3}}, {{1, 1}, {1, 5}}}

or

Pick[all, #[[1]] == 1 & /@ # & /@ all]
Pick[all, all[[All, All, 1]], 1]
Map[If[#[[1]] == 1, #, ## &[]] &, all, {2}]

all give

{{{1, 2}, {1, 3}}, {{1, 1}, {1, 5}}}

Select[#, #[[1]] == 1 &] & /@ all

{{{1, 2}, {1, 3}}, {{1, 1}, {1, 5}}}

or

Pick[all, #[[1]] == 1 & /@ # & /@ all]

{{{1, 2}, {1, 3}}, {{1, 1}, {1, 5}}}

Select[#, #[[1]] == 1 &] & /@ all
Pick[all, #[[1]] == 1 & /@ # & /@ all]
Pick[all, all[[All, All, 1]], 1]
Map[If[#[[1]] == 1, #, ## &[]] &, all, {2}]

all give

{{{1, 2}, {1, 3}}, {{1, 1}, {1, 5}}}

2 added 92 characters in body
source | link
Select[#, #[[1]] == 1 &] & /@ all

{{{1, 2}, {1, 3}}, {{1, 1}, {1, 5}}}

or

Pick[all, #[[1]] == 1 & /@ # & /@ all]

{{{1, 2}, {1, 3}}, {{1, 1}, {1, 5}}}

Select[#, #[[1]] == 1 &] & /@ all

{{{1, 2}, {1, 3}}, {{1, 1}, {1, 5}}}

Select[#, #[[1]] == 1 &] & /@ all

{{{1, 2}, {1, 3}}, {{1, 1}, {1, 5}}}

or

Pick[all, #[[1]] == 1 & /@ # & /@ all]

{{{1, 2}, {1, 3}}, {{1, 1}, {1, 5}}}

1
source | link