puzzling behavior of `.[]|=empty`
As far as I understand, the use of empty in update-assignment |= deletes the entry, similar to del(path), and del(path) also works in arrays.
I tried to selectively delete and modify array entries, and got strange results. While trying to understand the problem, I minimized the code to this:
Filter: .|=empty
Input: [0,1,2,3,4,5]
Output:[
1,
3,
5
]
Try it online here
Apparently, only even array indexes are deleted. Why?
jq
asked Nov 19 '18 at 20:05
user368683user368683
1264
add a comment |
As far as I understand, the use of empty in update-assignment |= deletes the entry, similar to del(path), and del(path) also works in arrays.
I tried to selectively delete and modify array entries, and got strange results. While trying to understand the problem, I minimized the code to this:
Filter: .|=empty
Input: [0,1,2,3,4,5]
Output:[
1,
3,
5
]
Try it online here
Apparently, only even array indexes are deleted. Why?
jq
asked Nov 19 '18 at 20:05
user368683user368683
1264
Interesting. The output injq1.5 (which until now I thought was the most recent version) isnull, whilejqplay.orgis using the recently released 1.6 version. I could imagine that|=andemptyare each consuming their own element from the input (emptytakes 0,|=takes 1, etc), but whether 1.5 or 1.6 is "correct", I couldn't say. (That is, it could be a bug fix or a regression in 1.6.)
– chepner
Nov 19 '18 at 20:15
add a comment |
As far as I understand, the use of empty in update-assignment |= deletes the entry, similar to del(path), and del(path) also works in arrays.
I tried to selectively delete and modify array entries, and got strange results. While trying to understand the problem, I minimized the code to this:
Filter: .|=empty
Input: [0,1,2,3,4,5]
Output:[
1,
3,
5
]
Try it online here
Apparently, only even array indexes are deleted. Why?
jq
asked Nov 19 '18 at 20:05
user368683user368683
1264
As far as I understand, the use of empty in update-assignment |= deletes the entry, similar to del(path), and del(path) also works in arrays.
I tried to selectively delete and modify array entries, and got strange results. While trying to understand the problem, I minimized the code to this:
Filter: .|=empty
Input: [0,1,2,3,4,5]
Output:[
1,
3,
5
]
Try it online here
Apparently, only even array indexes are deleted. Why?
jq
jq
asked Nov 19 '18 at 20:05
user368683user368683
1264
asked Nov 19 '18 at 20:05
user368683user368683
1264
asked Nov 19 '18 at 20:05
user368683user368683
1264
asked Nov 19 '18 at 20:05
user368683user368683
1264
asked Nov 19 '18 at 20:05
user368683user368683
1264
1264
Interesting. The output injq1.5 (which until now I thought was the most recent version) isnull, whilejqplay.orgis using the recently released 1.6 version. I could imagine that|=andemptyare each consuming their own element from the input (emptytakes 0,|=takes 1, etc), but whether 1.5 or 1.6 is "correct", I couldn't say. (That is, it could be a bug fix or a regression in 1.6.)
– chepner
Nov 19 '18 at 20:15
add a comment |
Interesting. The output injq1.5 (which until now I thought was the most recent version) isnull, whilejqplay.orgis using the recently released 1.6 version. I could imagine that|=andemptyare each consuming their own element from the input (emptytakes 0,|=takes 1, etc), but whether 1.5 or 1.6 is "correct", I couldn't say. (That is, it could be a bug fix or a regression in 1.6.)
– chepner
Nov 19 '18 at 20:15
Interesting. The output in
jq 1.5 (which until now I thought was the most recent version) is null, while jqplay.org is using the recently released 1.6 version. I could imagine that |= and empty are each consuming their own element from the input (empty takes 0, |= takes 1, etc), but whether 1.5 or 1.6 is "correct", I couldn't say. (That is, it could be a bug fix or a regression in 1.6.)– chepner
Nov 19 '18 at 20:15
Interesting. The output in
jq 1.5 (which until now I thought was the most recent version) is null, while jqplay.org is using the recently released 1.6 version. I could imagine that |= and empty are each consuming their own element from the input (empty takes 0, |= takes 1, etc), but whether 1.5 or 1.6 is "correct", I couldn't say. (That is, it could be a bug fix or a regression in 1.6.)– chepner
Nov 19 '18 at 20:15
add a comment |
1 Answer
1
active
oldest
votes
As noted in a comment, jq's treatment of . |= empty has varied over time. One might expect that for every array, A, A | (. |= empty) would yield on the theory that the expression should result in every item in A being replaced by empty.
In any case, the current (jq 1.6) implementation is clearly wrong, as is particularly noticeable in this example:
jq-1.6 -n '[0,1,2,3] | (. |= if . == 2 then empty else . end)'
[
0,
1,
3,
null
]
Bug reports can be submitted to https://github.com/stedolan/jq/issues
answered Nov 19 '18 at 21:08
peakpeak
32.3k93959
Thanks @peak for the example. I've used a variant in the jq GitHub issue
– user368683
Nov 21 '18 at 7:33
add a comment |
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1 Answer
1
active
oldest
votes
1 Answer
1
active
oldest
votes
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oldest
votes
active
oldest
votes
As noted in a comment, jq's treatment of . |= empty has varied over time. One might expect that for every array, A, A | (. |= empty) would yield on the theory that the expression should result in every item in A being replaced by empty.
In any case, the current (jq 1.6) implementation is clearly wrong, as is particularly noticeable in this example:
jq-1.6 -n '[0,1,2,3] | (. |= if . == 2 then empty else . end)'
[
0,
1,
3,
null
]
Bug reports can be submitted to https://github.com/stedolan/jq/issues
answered Nov 19 '18 at 21:08
peakpeak
32.3k93959
Thanks @peak for the example. I've used a variant in the jq GitHub issue
– user368683
Nov 21 '18 at 7:33
add a comment |
As noted in a comment, jq's treatment of . |= empty has varied over time. One might expect that for every array, A, A | (. |= empty) would yield on the theory that the expression should result in every item in A being replaced by empty.
In any case, the current (jq 1.6) implementation is clearly wrong, as is particularly noticeable in this example:
jq-1.6 -n '[0,1,2,3] | (. |= if . == 2 then empty else . end)'
[
0,
1,
3,
null
]
Bug reports can be submitted to https://github.com/stedolan/jq/issues
answered Nov 19 '18 at 21:08
peakpeak
32.3k93959
Thanks @peak for the example. I've used a variant in the jq GitHub issue
– user368683
Nov 21 '18 at 7:33
add a comment |
As noted in a comment, jq's treatment of . |= empty has varied over time. One might expect that for every array, A, A | (. |= empty) would yield on the theory that the expression should result in every item in A being replaced by empty.
In any case, the current (jq 1.6) implementation is clearly wrong, as is particularly noticeable in this example:
jq-1.6 -n '[0,1,2,3] | (. |= if . == 2 then empty else . end)'
[
0,
1,
3,
null
]
Bug reports can be submitted to https://github.com/stedolan/jq/issues
answered Nov 19 '18 at 21:08
peakpeak
32.3k93959
As noted in a comment, jq's treatment of . |= empty has varied over time. One might expect that for every array, A, A | (. |= empty) would yield on the theory that the expression should result in every item in A being replaced by empty.
In any case, the current (jq 1.6) implementation is clearly wrong, as is particularly noticeable in this example:
jq-1.6 -n '[0,1,2,3] | (. |= if . == 2 then empty else . end)'
[
0,
1,
3,
null
]
Bug reports can be submitted to https://github.com/stedolan/jq/issues
answered Nov 19 '18 at 21:08
peakpeak
32.3k93959
answered Nov 19 '18 at 21:08
peakpeak
32.3k93959
answered Nov 19 '18 at 21:08
peakpeak
32.3k93959
answered Nov 19 '18 at 21:08
peakpeak
32.3k93959
32.3k93959
Thanks @peak for the example. I've used a variant in the jq GitHub issue
– user368683
Nov 21 '18 at 7:33
add a comment |
Thanks @peak for the example. I've used a variant in the jq GitHub issue
– user368683
Nov 21 '18 at 7:33
Thanks @peak for the example. I've used a variant in the jq GitHub issue
– user368683
Nov 21 '18 at 7:33
Thanks @peak for the example. I've used a variant in the jq GitHub issue
– user368683
Nov 21 '18 at 7:33
add a comment |
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Interesting. The output in
jq1.5 (which until now I thought was the most recent version) isnull, whilejqplay.orgis using the recently released 1.6 version. I could imagine that|=andemptyare each consuming their own element from the input (emptytakes 0,|=takes 1, etc), but whether 1.5 or 1.6 is "correct", I couldn't say. (That is, it could be a bug fix or a regression in 1.6.)– chepner
Nov 19 '18 at 20:15