# Add elements to tuples or arrays
**URL:** https://discourse.julialang.org/t/add-elements-to-tuples-or-arrays/75885
**Category:** General Usage
**Tags:** arrays
**Created:** [February 6, 2022, 1:02am UTC](https://discourse.julialang.org/t/add-elements-to-tuples-or-arrays/75885 "2022-02-06T01:02:40Z")
**Posts on this page:** 13
**Page:** 2
### Author:  [@lmiq](https://discourse.julialang.org/u/lmiq)
#### Post date: [February 6, 2022, 7:16pm UTC](https://discourse.julialang.org/t/add-elements-to-tuples-or-arrays/75885/21 "2022-02-06T19:16:03Z")
> [@Leticia-maria](#):
>
> ` for cyc in cycs`
I didn’t look at the details, but from the discussion above you should use `for (_, cyc) in pairs(cycs)` here.
---
### Author:  [@Leticia-maria](https://discourse.julialang.org/u/Leticia-maria)
#### Post date: [February 6, 2022, 7:19pm UTC](https://discourse.julialang.org/t/add-elements-to-tuples-or-arrays/75885/22 "2022-02-06T19:19:01Z")
Thank you, have you an alternative for using `ase` with pycall? I’d like to use a julia package to extract the neighborlists from xyz files
---
### Author:  [@lmiq](https://discourse.julialang.org/u/lmiq)
#### Post date: [February 6, 2022, 7:32pm UTC](https://discourse.julialang.org/t/add-elements-to-tuples-or-arrays/75885/23 "2022-02-06T19:32:16Z")
I had never heard of ase before, thus no idea.
---
### Author:  [@Henrique\_Becker](https://discourse.julialang.org/u/Henrique_Becker)
#### Post date: [February 6, 2022, 8:36pm UTC](https://discourse.julialang.org/t/add-elements-to-tuples-or-arrays/75885/24 "2022-02-06T20:36:38Z")
> [@lmiq](#):
>
> I didn’t look at the details, but from the discussion above you should use `for (_, cyc) in pairs(cycs)` here.
Not really, the code does not seem to be appending to `cycs` while traversing it, so I am not sure anymore if this is the reason of the infinite loop.
I did not inspect all the code but:
```julia
for (i_v, j_v) in zip(nl[1], nl[2])
push!(new[i_v + 1], j_v)
end
```
Is probably wrong, because you are changing the identifier of the nodes but not the references to them. This is, you are saying that now node `0` is node `1`, node `1` is node `2` and so on, but the `j_v` is referring to the nodes by their old numbers, starting at `0`. I see some `+1` and `-1` in some variables that may be trying to fix this inconsistency, however, the ideal solution is to either change all indexes to base 1 at the start and then reduce 1 at after the end, or do not change the indexes at all (you are using an `OrderedDict` not a `Vector`, you do not need to start at base 1 if this is were you will keep all the references).
You should probably make the `.xyz` files available to us if you want us to run the code trying to find the problem. Even if most people (I included) will probably not install Python and some Python library to run the code. Instead, a code with the object `ase_atoms_no_h` hardcoded would be ideal for us to check for problems.
---
### Author:  [@Leticia-maria](https://discourse.julialang.org/u/Leticia-maria)
#### Post date: [February 6, 2022, 8:44pm UTC](https://discourse.julialang.org/t/add-elements-to-tuples-or-arrays/75885/25 "2022-02-06T20:44:15Z")
The xyz file
```julia
168
Properties=species:S:1:pos:R:3 a=T pbc="F F F"
C -12.39796606 5.75557728 -0.00041200
C -11.19877446 5.02970593 -0.00032500
C -12.39394703 7.14159987 -0.00041400
C -11.19681055 7.84012337 -0.00032400
C -9.96744844 7.16661422 -0.00023300
C -9.96819366 5.74383274 -0.00024000
C -11.18330163 3.57177356 -0.00031300
C -9.94599750 2.87057938 -0.00023200
C -8.72064338 3.60828242 -0.00016200
C -8.72310290 5.02638964 -0.00016200
C -7.49496079 5.73540164 -0.00008200
C -7.47119819 7.16548340 -0.00006000
C -8.69832579 7.88433709 -0.00012800
C -8.64244256 9.28197414 -0.00008900
C -7.43982971 9.95371555 0.00002900
C -6.21247989 9.27715558 0.00010500
C -6.22187177 7.86472647 0.00003800
C -4.97636979 7.12169735 0.00007500
C -5.03553510 5.75021698 0.00006300
C -6.26161667 5.01942371 -0.00000900
C -7.48271125 2.90026830 -0.00008500
C -6.28203360 3.61980199 -0.00001300
C -7.50012903 1.47302251 -0.00008200
C -8.65702774 0.73407711 -0.00014500
C -9.92446254 1.43904343 -0.00021700
C -11.14174854 0.72262286 -0.00026600
C -12.34257130 1.44521981 -0.00034900
C -12.36447512 2.82254806 -0.00037400
C -11.18344950 -7.85916442 -0.00005400
C -9.95523438 -7.18356547 -0.00004800
C -12.38177302 -7.16267824 -0.00009000
C -12.38815194 -5.77666563 -0.00012300
C -11.19019759 -5.04875581 -0.00012000
C -9.95840276 -5.76078798 -0.00008100
C -8.68488954 -7.89912934 -0.00001100
C -7.45898928 -7.17818687 -0.00000900
C -7.48518665 -5.74814774 -0.00003800
C -8.71453531 -5.04122633 -0.00007300
C -8.71448956 -3.62311770 -0.00009900
C -9.94109821 -2.88750101 -0.00014100
C -11.17720663 -3.59079847 -0.00015600
C -12.35965442 -2.84358337 -0.00020600
C -12.34009569 -1.46621958 -0.00024100
C -11.14050425 -0.74158212 -0.00022600
C -9.92200007 -1.45593064 -0.00016900
C -8.65576609 -0.74880892 -0.00014100
C -7.49761137 -1.48578514 -0.00010700
C -7.47776502 -2.91299915 -0.00008800
C -6.25306491 -5.03007198 -0.00003100
C -6.27586411 -3.63048832 -0.00005500
C -5.02574116 -5.75877619 0.00000000
C -4.96423994 -7.13015173 0.00002500
C -6.20847340 -7.87530143 0.00002300
C -6.19667499 -9.28771224 0.00005400
C -7.42286943 -9.96636153 0.00005600
C -8.62662507 -9.29666966 0.00002400
C 1.21450823 -13.61472667 0.00022800
C 1.24353338 -12.21325957 0.00019700
C 0.01216833 -14.30425732 0.00023100
C -1.19134122 -13.61676991 0.00020300
C -1.22274459 -12.21535646 0.00017100
C 0.00979104 -11.50461068 0.00016900
C 2.49840294 -11.47089481 0.00019400
C 2.48700183 -10.04876049 0.00015900
C 1.23545432 -9.35642485 0.00013300
C 0.00856839 -10.06760901 0.00013700
C -1.21952599 -9.35851261 0.00011100
C -2.46989304 -10.05297615 0.00011200
C -2.47887384 -11.47512729 0.00014000
C -3.71720311 -12.12555146 0.00013700
C -4.90025658 -11.41993218 0.00010900
C -4.92801419 -10.01873685 0.00008300
C -3.70011978 -9.32065305 0.00008300
C -3.67939065 -7.87050088 0.00005500
C -2.46207174 -7.23599761 0.00005600
C -1.21614479 -7.93241823 0.00008200
C 1.22964557 -7.93033819 0.00010200
C 0.00617072 -7.25028844 0.00007900
C 2.47438565 -7.23180047 0.00009300
C 3.69278161 -7.86423016 0.00011300
C 3.71598009 -9.31434484 0.00015200
C 4.94506338 -10.01033595 0.00018300
C 4.91968930 -11.41157691 0.00021900
C 3.73783892 -12.11920941 0.00022400
C 12.39796607 -5.75557729 0.00006900
C 11.19877447 -5.02970594 0.00003000
C 12.39394714 -7.14159888 0.00013300
C 11.19681155 -7.84012350 0.00015900
C 9.96744844 -7.16661423 0.00012300
C 9.96819366 -5.74383275 0.00006200
C 11.18330164 -3.57177357 -0.00004200
C 9.94599650 -2.87057927 -0.00006400
C 8.72064339 -3.60828242 -0.00002400
C 8.72310291 -5.02638964 0.00003200
C 7.49496079 -5.73540164 0.00005800
C 7.47119819 -7.16548341 0.00011100
C 8.69832579 -7.88433709 0.00014500
C 8.64244256 -9.28197414 0.00019700
C 7.43982971 -9.95371556 0.00021100
C 6.21247977 -9.27715658 0.00017500
C 6.22187277 -7.86472660 0.00012800
C 4.97636979 -7.12169735 0.00009600
C 5.03553511 -5.75021699 0.00004900
C 6.26161657 -5.01942471 0.00002800
C 7.48271126 -2.90026831 -0.00004800
C 6.28203249 -3.61980289 -0.00002200
C 7.50012804 -1.47302240 -0.00009600
C 8.65702674 -0.73407700 -0.00012700
C 9.92446254 -1.43904344 -0.00012900
C 11.14174854 -0.72262287 -0.00019800
C 12.34257131 -1.44521982 -0.00017100
C 12.36447512 -2.82254807 -0.00009200
C 11.18345049 7.85916430 -0.00054900
C 9.95523438 7.18356546 -0.00041400
C 12.38177390 7.16267712 -0.00065100
C 12.38815183 5.77666463 -0.00061500
C 11.19019759 5.04875580 -0.00048200
C 9.95840277 5.76078797 -0.00038900
C 8.68488966 7.89913033 -0.00029400
C 7.45898939 7.17818786 -0.00018300
C 7.48518666 5.74814773 -0.00017700
C 8.71453543 5.04122732 -0.00026800
C 8.71448858 3.62311780 -0.00023600
C 9.94109721 2.88750112 -0.00031000
C 11.17720663 3.59079846 -0.00043100
C 12.35965442 2.84358336 -0.00049100
C 12.34009569 1.46621958 -0.00042100
C 11.14050325 0.74158222 -0.00029400
C 9.92199909 1.45593074 -0.00025500
C 8.65576510 0.74880902 -0.00015400
C 7.49761050 1.48578624 -0.00008500
C 7.47776402 2.91299926 -0.00011800
C 6.25306492 5.03007198 -0.00006300
C 6.27586311 3.63048842 -0.00003700
C 5.02574017 5.75877631 0.00002100
C 4.96424006 7.13015272 0.00000800
C 6.20847340 7.87530143 -0.00006800
C 6.19667511 9.28771322 -0.00002000
C 7.42286943 9.96636153 -0.00014100
C 8.62662507 9.29666965 -0.00027900
C -1.21450933 13.61472577 0.00072000
C -1.24353337 12.21325957 0.00055900
C -0.01216931 14.30425744 0.00079100
C 1.19134024 13.61677001 0.00069700
C 1.22274459 12.21535645 0.00053600
C -0.00979104 11.50461067 0.00047600
C -2.49840294 11.47089480 0.00047000
C -2.48700182 10.04876048 0.00032700
C -1.23545432 9.35642485 0.00026700
C -0.00856839 10.06760901 0.00033000
C 1.21952599 9.35851261 0.00024600
C 2.46989315 10.05297714 0.00028200
C 2.47887385 11.47512729 0.00042100
C 3.71720312 12.12555145 0.00043800
C 4.90025670 11.41993317 0.00030300
C 4.92801419 10.01873684 0.00015300
C 3.70011990 9.32065404 0.00017000
C 3.67939076 7.87050186 0.00006700
C 2.46207284 7.23599848 0.00002800
C 1.21614479 7.93241823 0.00010800
C -1.22964458 7.93033807 0.00012700
C -0.00616972 7.25028833 0.00005400
C -2.47438477 7.23179936 0.00006600
C -3.69278061 7.86423003 0.00012300
C -3.71598008 9.31434484 0.00023600
C -4.94506239 10.01033583 0.00025100
C -4.91968830 11.41157679 0.00040300
C -3.73783892 12.11920941 0.00051400
```
---
### Author:  [@Leticia-maria](https://discourse.julialang.org/u/Leticia-maria)
#### Post date: [February 6, 2022, 8:56pm UTC](https://discourse.julialang.org/t/add-elements-to-tuples-or-arrays/75885/26 "2022-02-06T20:56:24Z")
@DNF, @Henrique_Becker, The variables
```julia
> ase_atoms_no_h
PyObject Atoms(symbols='C168', pbc=False)
> neighborlist = pyimport("ase.neighborlist")
> neighbor_list = neighborlist.neighbor_list("ij", ase_atoms_no_h, 2.0)
> print(neighbor_list)
([0, 0, 1, 1, 1, 2, 2, 3, 3, 4, 4, 4, 5, 5, 5, 6, 6, 6, 7, 7, 7, 8, 8, 8, 9, 9, 9, 10, 10, 10, 11, 11, 11, 12, 12, 12, 13, 13, 14, 14, 15, 15, 15, 16, 16, 16, 17, 17, 17, 18, 18, 19, 19, 19, 20, 20, 20, 21, 21, 22, 22, 23, 23, 23, 24, 24, 24, 25, 25, 25, 26, 26, 27, 27, 28, 28, 29, 29, 29, 30, 30, 31, 31, 32, 32, 32, 33, 33, 33, 34, 34, 34, 35, 35, 35, 36, 36, 36, 37, 37, 37, 38, 38, 38, 39, 39, 39, 40, 40, 40, 41, 41, 42, 42, 43, 43, 43, 44, 44, 44, 45, 45, 45, 46, 46, 47, 47, 47, 48, 48, 48, 49, 49, 50, 50, 51, 51, 51, 52, 52, 52, 53, 53, 53, 54, 54, 55, 55, 56, 56, 57, 57, 57, 58, 58, 59, 59, 60, 60, 60, 61, 61, 61, 62, 62, 62, 63, 63, 63, 64, 64, 64, 65, 65, 65, 66, 66, 66, 67, 67, 67, 68, 68, 68, 69, 69, 70, 70, 71, 71, 71, 72, 72, 72, 73, 73, 73, 74, 74, 75, 75, 75, 76, 76, 76, 77, 77, 78, 78, 79, 79, 79, 80, 80, 80, 81, 81, 81, 82, 82, 83, 83, 84, 84, 85, 85, 85, 86, 86, 87, 87, 88, 88, 88, 89, 89, 89, 90, 90, 90, 91, 91, 91, 92, 92, 92, 93, 93, 93, 94, 94, 94, 95, 95, 95, 96, 96, 96, 97, 97, 98, 98, 99, 99, 99, 100, 100, 100, 101, 101, 101, 102, 102, 103, 103, 103, 104, 104, 104, 105, 105, 106, 106, 107, 107, 107, 108, 108, 108, 109, 109, 109, 110, 110, 111, 111, 112, 112, 113, 113, 113, 114, 114, 115, 115, 116, 116, 116, 117, 117, 117, 118, 118, 118, 119, 119, 119, 120, 120, 120, 121, 121, 121, 122, 122, 122, 123, 123, 123, 124, 124, 124, 125, 125, 126, 126, 127, 127, 127, 128, 128, 128, 129, 129, 129, 130, 130, 131, 131, 131, 132, 132, 132, 133, 133, 134, 134, 135, 135, 135, 136, 136, 136, 137, 137, 137, 138, 138, 139, 139, 140, 140, 141, 141, 141, 142, 142, 143, 143, 144, 144, 144, 145, 145, 145, 146, 146, 146, 147, 147, 147, 148, 148, 148, 149, 149, 149, 150, 150, 150, 151, 151, 151, 152, 152, 152, 153, 153, 154, 154, 155, 155, 155, 156, 156, 156, 157, 157, 157, 158, 158, 159, 159, 159, 160, 160, 160, 161, 161, 162, 162, 163, 163, 163, 164, 164, 164, 165, 165, 165, 166, 166, 167, 167], [2, 1, 5, 6, 0, 3, 0, 4, 2, 5, 3, 12, 1, 4, 9, 7, 1, 27, 8, 6, 24, 9, 7, 20, 5, 10, 8, 9, 11, 19, 12, 16, 10, 4, 11, 13, 12, 14, 13, 15, 14, 16, 165, 11, 15, 17, 16, 18, 163, 19, 17, 21, 10, 18, 8, 22, 21, 19, 20, 20, 23, 24, 22, 45, 7, 23, 25, 24, 26, 43, 25, 27, 6, 26, 29, 30, 28, 33, 34, 28, 31, 30, 32, 40, 31, 33, 29, 32, 37, 29, 35, 55, 34, 36, 52, 35, 37, 48, 36, 38, 33, 37, 39, 47, 40, 38, 44, 39, 32, 41, 42, 40, 41, 43, 25, 44, 42, 39, 45, 43, 23, 46, 44, 47, 45, 38, 46, 49, 36, 49, 50, 47, 48, 48, 51, 50, 73, 52, 53, 51, 35, 71, 54, 52, 55, 53, 54, 34, 57, 58, 61, 56, 62, 56, 59, 58, 60, 59, 68, 61, 60, 57, 65, 57, 63, 83, 80, 62, 64, 63, 76, 65, 66, 61, 64, 65, 67, 75, 66, 68, 72, 60, 67, 69, 68, 70, 69, 71, 53, 70, 72, 67, 71, 73, 74, 72, 51, 73, 75, 66, 74, 77, 77, 78, 64, 76, 75, 76, 79, 78, 80, 101, 79, 81, 63, 80, 82, 99, 83, 81, 62, 82, 85, 86, 84, 90, 89, 87, 84, 86, 88, 87, 89, 96, 88, 93, 85, 91, 111, 85, 90, 92, 108, 91, 93, 104, 89, 92, 94, 103, 93, 95, 94, 96, 100, 88, 95, 97, 96, 98, 97, 99, 81, 98, 100, 95, 99, 101, 79, 100, 102, 103, 101, 94, 102, 105, 106, 105, 92, 104, 103, 107, 104, 129, 106, 108, 91, 107, 109, 108, 110, 127, 109, 111, 90, 110, 113, 114, 112, 117, 118, 112, 115, 114, 116, 124, 115, 117, 113, 116, 121, 113, 119, 139, 118, 120, 136, 119, 121, 132, 117, 120, 122, 121, 123, 131, 124, 122, 128, 123, 116, 125, 126, 124, 127, 125, 126, 128, 109, 123, 129, 127, 107, 128, 130, 129, 131, 122, 130, 133, 120, 133, 134, 131, 132, 132, 135, 134, 136, 157, 137, 135, 119, 136, 138, 155, 137, 139, 118, 138, 141, 142, 140, 146, 145, 140, 143, 142, 144, 143, 145, 152, 149, 141, 144, 141, 147, 167, 164, 148, 146, 160, 149, 147, 150, 145, 148, 151, 149, 159, 150, 152, 156, 144, 153, 151, 152, 154, 153, 155, 137, 154, 156, 151, 155, 157, 135, 156, 158, 157, 159, 161, 158, 150, 148, 162, 161, 159, 160, 163, 160, 164, 162, 17, 163, 165, 147, 15, 166, 164, 167, 165, 166, 146])
> a = convert_neighbor_list(neighbor_list)
> print(a)
OrderedDict{Any, Any}(1 => [2, 1], 2 => [5, 6, 0], 3 => [3, 0], 4 => [4, 2], 5 => [5, 3, 12], 6 => [1, 4, 9], 7 => [7, 1, 27], 8 => [8, 6, 24], 9 => [9, 7, 20], 10 => [5, 10, 8], 11 => [9, 11, 19], 12 => [12, 16, 10], 13 => [4, 11, 13], 14 => [12, 14], 15 => [13, 15], 16 => [14, 16, 165], 17 => [11, 15, 17], 18 => [16, 18, 163], 19 => [19, 17], 20 => [21, 10, 18], 21 => [8, 22, 21], 22 => [19, 20], 23 => [20, 23], 24 => [24, 22, 45], 25 => [7, 23, 25], 26 => [24, 26, 43], 27 => [25, 27], 28 => [6, 26], 29 => [29, 30], 30 => [28, 33, 34], 31 => [28, 31], 32 => [30, 32], 33 => [40, 31, 33], 34 => [29, 32, 37], 35 => [29, 35, 55], 36 => [34, 36, 52], 37 => [35, 37, 48], 38 => [36, 38, 33], 39 => [37, 39, 47], 40 => [40, 38, 44], 41 => [39, 32, 41], 42 => [42, 40], 43 => [41, 43], 44 => [25, 44, 42], 45 => [39, 45, 43], 46 => [23, 46, 44], 47 => [47, 45], 48 => [38, 46, 49], 49 => [36, 49, 50], 50 => [47, 48], 51 => [48, 51], 52 => [50, 73, 52], 53 => [53, 51, 35], 54 => [71, 54, 52], 55 => [55, 53], 56 => [54, 34], 57 => [57, 58], 58 => [61, 56, 62], 59 => [56, 59], 60 => [58, 60], 61 => [59, 68, 61], 62 => [60, 57, 65], 63 => [57, 63, 83], 64 => [80, 62, 64], 65 => [63, 76, 65], 66 => [66, 61, 64], 67 => [65, 67, 75], 68 => [66, 68, 72], 69 => [60, 67, 69], 70 => [68, 70], 71 => [69, 71], 72 => [53, 70, 72], 73 => [67, 71, 73], 74 => [74, 72, 51], 75 => [73, 75], 76 => [66, 74, 77], 77 => [77, 78, 64], 78 => [76, 75], 79 => [76, 79], 80 => [78, 80, 101], 81 => [79, 81, 63], 82 => [80, 82, 99], 83 => [83, 81], 84 => [62, 82], 85 => [85, 86], 86 => [84, 90, 89], 87 => [87, 84], 88 => [86, 88], 89 => [87, 89, 96], 90 => [88, 93, 85], 91 => [91, 111, 85], 92 => [90, 92, 108], 93 => [91, 93, 104], 94 => [89, 92, 94], 95 => [103, 93, 95], 96 => [94, 96, 100], 97 => [88, 95, 97], 98 => [96, 98], 99 => [97, 99], 100 => [81, 98, 100], 101 => [95, 99, 101], 102 => [79, 100, 102], 103 => [103, 101], 104 => [94, 102, 105], 105 => [106, 105, 92], 106 => [104, 103], 107 => [107, 104], 108 => [129, 106, 108], 109 => [91, 107, 109], 110 => [108, 110, 127], 111 => [109, 111], 112 => [90, 110], 113 => [113, 114], 114 => [112, 117, 118], 115 => [112, 115], 116 => [114, 116], 117 => [124, 115, 117], 118 => [113, 116, 121], 119 => [113, 119, 139], 120 => [118, 120, 136], 121 => [119, 121, 132], 122 => [117, 120, 122], 123 => [121, 123, 131], 124 => [124, 122, 128], 125 => [123, 116, 125], 126 => [126, 124], 127 => [127, 125], 128 => [126, 128, 109], 129 => [123, 129, 127], 130 => [107, 128, 130], 131 => [129, 131], 132 => [122, 130, 133], 133 => [120, 133, 134], 134 => [131, 132], 135 => [132, 135], 136 => [134, 136, 157], 137 => [137, 135, 119], 138 => [136, 138, 155], 139 => [137, 139], 140 => [118, 138], 141 => [141, 142], 142 => [140, 146, 145], 143 => [140, 143], 144 => [142, 144], 145 => [143, 145, 152], 146 => [149, 141, 144], 147 => [141, 147, 167], 148 => [164, 148, 146], 149 => [160, 149, 147], 150 => [150, 145, 148], 151 => [151, 149, 159], 152 => [150, 152, 156], 153 => [144, 153, 151], 154 => [152, 154], 155 => [153, 155], 156 => [137, 154, 156], 157 => [151, 155, 157], 158 => [135, 156, 158], 159 => [157, 159], 160 => [161, 158, 150], 161 => [148, 162, 161], 162 => [159, 160], 163 => [163, 160], 164 => [164, 162, 17], 165 => [163, 165, 147], 166 => [15, 166, 164], 167 => [167, 165], 168 => [166, 146])
```
---
### Author:  [@lmiq](https://discourse.julialang.org/u/lmiq)
#### Post date: [February 6, 2022, 9:19pm UTC](https://discourse.julialang.org/t/add-elements-to-tuples-or-arrays/75885/27 "2022-02-06T21:19:59Z")
That neighbor list is distance based (easy) or is it based on the chemical nature and valence of each atom?
---
### Author:  [@Henrique\_Becker](https://discourse.julialang.org/u/Henrique_Becker)
#### Post date: [February 7, 2022, 4:04pm UTC](https://discourse.julialang.org/t/add-elements-to-tuples-or-arrays/75885/28 "2022-02-07T16:04:14Z")
Unfortunately, I found the original code to be too confusing, and in the end I rewrote the whole algorithm. One thing I was not sure during the implementation is if you are interested only on cycles of exactly length 6? Or any length smaller than 6 will do? My implementation only gets the cycles of size 6, but is easy to change this.
```julia
using LinearAlgebra
using Statistics
using DataStructures
const edges = ([0, 0, 1, 1, 1, 2, 2, 3, 3, 4, 4, 4, 5, 5, 5, 6, 6, 6, 7, 7, 7, 8, 8, 8, 9, 9, 9, 10, 10, 10, 11, 11, 11, 12, 12, 12, 13, 13, 14, 14, 15, 15, 15, 16, 16, 16, 17, 17, 17, 18, 18, 19, 19, 19, 20, 20, 20, 21, 21, 22, 22, 23, 23, 23, 24, 24, 24, 25, 25, 25, 26, 26, 27, 27, 28, 28, 29, 29, 29, 30, 30, 31, 31, 32, 32, 32, 33, 33, 33, 34, 34, 34, 35, 35, 35, 36, 36, 36, 37, 37, 37, 38, 38, 38, 39, 39, 39, 40, 40, 40, 41, 41, 42, 42, 43, 43, 43, 44, 44, 44, 45, 45, 45, 46, 46, 47, 47, 47, 48, 48, 48, 49, 49, 50, 50, 51, 51, 51, 52, 52, 52, 53, 53, 53, 54, 54, 55, 55, 56, 56, 57, 57, 57, 58, 58, 59, 59, 60, 60, 60, 61, 61, 61, 62, 62, 62, 63, 63, 63, 64, 64, 64, 65, 65, 65, 66, 66, 66, 67, 67, 67, 68, 68, 68, 69, 69, 70, 70, 71, 71, 71, 72, 72, 72, 73, 73, 73, 74, 74, 75, 75, 75, 76, 76, 76, 77, 77, 78, 78, 79, 79, 79, 80, 80, 80, 81, 81, 81, 82, 82, 83, 83, 84, 84, 85, 85, 85, 86, 86, 87, 87, 88, 88, 88, 89, 89, 89, 90, 90, 90, 91, 91, 91, 92, 92, 92, 93, 93, 93, 94, 94, 94, 95, 95, 95, 96, 96, 96, 97, 97, 98, 98, 99, 99, 99, 100, 100, 100, 101, 101, 101, 102, 102, 103, 103, 103, 104, 104, 104, 105, 105, 106, 106, 107, 107, 107, 108, 108, 108, 109, 109, 109, 110, 110, 111, 111, 112, 112, 113, 113, 113, 114, 114, 115, 115, 116, 116, 116, 117, 117, 117, 118, 118, 118, 119, 119, 119, 120, 120, 120, 121, 121, 121, 122, 122, 122, 123, 123, 123, 124, 124, 124, 125, 125, 126, 126, 127, 127, 127, 128, 128, 128, 129, 129, 129, 130, 130, 131, 131, 131, 132, 132, 132, 133, 133, 134, 134, 135, 135, 135, 136, 136, 136, 137, 137, 137, 138, 138, 139, 139, 140, 140, 141, 141, 141, 142, 142, 143, 143, 144, 144, 144, 145, 145, 145, 146, 146, 146, 147, 147, 147, 148, 148, 148, 149, 149, 149, 150, 150, 150, 151, 151, 151, 152, 152, 152, 153, 153, 154, 154, 155, 155, 155, 156, 156, 156, 157, 157, 157, 158, 158, 159, 159, 159, 160, 160, 160, 161, 161, 162, 162, 163, 163, 163, 164, 164, 164, 165, 165, 165, 166, 166, 167, 167], [2, 1, 5, 6, 0, 3, 0, 4, 2, 5, 3, 12, 1, 4, 9, 7, 1, 27, 8, 6, 24, 9, 7, 20, 5, 10, 8, 9, 11, 19, 12, 16, 10, 4, 11, 13, 12, 14, 13, 15, 14, 16, 165, 11, 15, 17, 16, 18, 163, 19, 17, 21, 10, 18, 8, 22, 21, 19, 20, 20, 23, 24, 22, 45, 7, 23, 25, 24, 26, 43, 25, 27, 6, 26, 29, 30, 28, 33, 34, 28, 31, 30, 32, 40, 31, 33, 29, 32, 37, 29, 35, 55, 34, 36, 52, 35, 37, 48, 36, 38, 33, 37, 39, 47, 40, 38, 44, 39, 32, 41, 42, 40, 41, 43, 25, 44, 42, 39, 45, 43, 23, 46, 44, 47, 45, 38, 46, 49, 36, 49, 50, 47, 48, 48, 51, 50, 73, 52, 53, 51, 35, 71, 54, 52, 55, 53, 54, 34, 57, 58, 61, 56, 62, 56, 59, 58, 60, 59, 68, 61, 60, 57, 65, 57, 63, 83, 80, 62, 64, 63, 76, 65, 66, 61, 64, 65, 67, 75, 66, 68, 72, 60, 67, 69, 68, 70, 69, 71, 53, 70, 72, 67, 71, 73, 74, 72, 51, 73, 75, 66, 74, 77, 77, 78, 64, 76, 75, 76, 79, 78, 80, 101, 79, 81, 63, 80, 82, 99, 83, 81, 62, 82, 85, 86, 84, 90, 89, 87, 84, 86, 88, 87, 89, 96, 88, 93, 85, 91, 111, 85, 90, 92, 108, 91, 93, 104, 89, 92, 94, 103, 93, 95, 94, 96, 100, 88, 95, 97, 96, 98, 97, 99, 81, 98, 100, 95, 99, 101, 79, 100, 102, 103, 101, 94, 102, 105, 106, 105, 92, 104, 103, 107, 104, 129, 106, 108, 91, 107, 109, 108, 110, 127, 109, 111, 90, 110, 113, 114, 112, 117, 118, 112, 115, 114, 116, 124, 115, 117, 113, 116, 121, 113, 119, 139, 118, 120, 136, 119, 121, 132, 117, 120, 122, 121, 123, 131, 124, 122, 128, 123, 116, 125, 126, 124, 127, 125, 126, 128, 109, 123, 129, 127, 107, 128, 130, 129, 131, 122, 130, 133, 120, 133, 134, 131, 132, 132, 135, 134, 136, 157, 137, 135, 119, 136, 138, 155, 137, 139, 118, 138, 141, 142, 140, 146, 145, 140, 143, 142, 144, 143, 145, 152, 149, 141, 144, 141, 147, 167, 164, 148, 146, 160, 149, 147, 150, 145, 148, 151, 149, 159, 150, 152, 156, 144, 153, 151, 152, 154, 153, 155, 137, 154, 156, 151, 155, 157, 135, 156, 158, 157, 159, 161, 158, 150, 148, 162, 161, 159, 160, 163, 160, 164, 162, 17, 163, 165, 147, 15, 166, 164, 167, 165, 166, 146])
function edges2neighbors(xs, ys)
# The input is base-zero, this is the reason for the "+1".
max_vertex = max(maximum(xs), maximum(ys)) + 1
neighbors = Vector{Int}[Int[] for i in 1:max_vertex]
for (i_v, j_v) in zip(xs, ys)
# Again, we updated every node number from base zero to base one.
push!(neighbors[i_v + 1], j_v + 1)
end
return neighbors
end
function inner_dfs_cycle_detection!(cycles, candidate, neighbors, cycle_length)
@assert length(candidate) <= cycle_length
for next_vertex in neighbors[last(candidate)]
if next_vertex == first(candidate)
# The cycle needs to have exactly length 6?
if length(candidate) < cycle_length
continue
else
push!(cycles, copy(candidate))
end
elseif next_vertex in candidate
# Do not cycle back to the middle of candidate.
continue
elseif length(candidate) < cycle_length
# If the candidate does not have a subcycle and it is smaller
# than the desired cycle length, then recurse.
push!(candidate, next_vertex)
inner_dfs_cycle_detection!(cycles, candidate, neighbors, cycle_length)
end
end
return
end
function dfs_cycle_detection(neighbors, cycle_length)
cycles = Vector{eltype(neighbors)}()
for initial_vertex in eachindex(neighbors)
inner_dfs_cycle_detection!(cycles, [initial_vertex], neighbors, cycle_length)
end
return cycles
end
neighbors = edges2neighbors(edges[1], edges[2])
cycles_base_1 = dfs_cycle_detection(neighbors, 6)
cycles_base_0 = map(vertices -> vertices .- 1, cycles_base_1)
println(cycles_base_0)
```
and the output
```julia
[[0, 2, 3, 4, 5, 1], [0, 2, 3, 4, 5, 1], [1, 5, 4, 3, 2, 0], [2, 3, 4, 5, 1, 6], [3, 4, 5, 1, 6, 7], [4, 5, 1, 6, 7, 8], [5, 1, 6, 7, 8, 9], [6, 7, 8, 9, 5, 1], [6, 7, 8, 9, 5, 1], [7, 8, 9, 5, 1, 6], [7, 8, 9, 5, 1, 6], [8, 9, 5, 1, 6, 7], [8, 9, 5, 1, 6, 7], [9, 5, 1, 6, 7, 8], [9, 5, 1, 6, 7, 8], [10, 9, 5, 1, 6, 7], [11, 12, 4, 5, 1, 6], [12, 4, 5, 1, 6, 7], [13, 12, 4, 5, 1, 6], [14, 13, 12, 4, 5, 1], [15, 14, 13, 12, 4, 5], [16, 11, 12, 4, 5, 1], [17, 16, 11, 12, 4, 5], [18, 19, 21, 20, 8, 9], [20, 8, 9, 5, 1, 6], [22, 20, 8, 9, 5, 1], [23, 24, 7, 8, 9, 5], [24, 7, 8, 9, 5, 1], [25, 24, 7, 8, 9, 5], [26, 25, 24, 7, 8, 9], [27, 6, 7, 8, 9, 5], [30, 28, 29, 33, 32, 40], [31, 30, 28, 29, 33, 32], [31, 30, 28, 29, 33, 32], [32, 40, 39, 38, 37, 36], [33, 29, 28, 30, 31, 32], [33, 29, 28, 30, 31, 32], [34, 29, 28, 30, 31, 32], [35, 34, 29, 28, 30, 31], [36, 35, 34, 29, 28, 30], [37, 36, 35, 34, 29, 28], [38, 37, 36, 35, 34, 29], [43, 25, 24, 7, 8, 9], [44, 39, 40, 32, 31, 30], [45, 23, 24, 7, 8, 9], [46, 47, 38, 37, 36, 35], [47, 38, 37, 36, 35, 34], [48, 36, 35, 34, 29, 28], [49, 47, 38, 37, 36, 35], [50, 48, 36, 35, 34, 29], [51, 50, 48, 36, 35, 34], [52, 53, 71, 70, 69, 68], [56, 57, 61, 60, 59, 58], [56, 57, 61, 60, 59, 58], [57, 61, 60, 59, 58, 56], [57, 61, 60, 59, 58, 56], [58, 56, 57, 61, 60, 59], [58, 56, 57, 61, 60, 59], [59, 58, 56, 57, 61, 60], [59, 58, 56, 57, 61, 60], [60, 59, 58, 56, 57, 61], [60, 59, 58, 56, 57, 61], [61, 60, 59, 58, 56, 57], [61, 60, 59, 58, 56, 57], [62, 57, 61, 60, 59, 58], [63, 80, 79, 78, 76, 77], [64, 63, 80, 79, 78, 76], [64, 63, 80, 79, 78, 76], [67, 66, 65, 61, 60, 59], [68, 60, 59, 58, 56, 57], [69, 68, 60, 59, 58, 56], [70, 69, 68, 60, 59, 58], [72, 67, 66, 65, 61, 60], [75, 66, 65, 61, 60, 59], [78, 76, 77, 75, 66, 65], [79, 78, 76, 77, 75, 66], [80, 79, 78, 76, 77, 75], [81, 80, 79, 78, 76, 77], [82, 83, 62, 57, 61, 60], [83, 62, 57, 61, 60, 59], [85, 84, 86, 87, 88, 89], [88, 87, 86, 84, 85, 90], [89, 88, 87, 86, 84, 85], [89, 88, 87, 86, 84, 85], [91, 90, 111, 110, 109, 108], [92, 91, 90, 111, 110, 109], [93, 89, 88, 87, 86, 84], [95, 94, 103, 102, 101, 79], [96, 88, 87, 86, 84, 85], [97, 96, 88, 87, 86, 84], [98, 97, 96, 88, 87, 86], [99, 81, 80, 79, 78, 76], [100, 95, 94, 103, 102, 101], [100, 95, 94, 103, 102, 101], [101, 79, 78, 76, 77, 75], [102, 103, 94, 93, 89, 88], [104, 106, 107, 129, 128, 123], [105, 104, 106, 107, 129, 128], [106, 107, 129, 128, 123, 124], [108, 91, 90, 111, 110, 109], [108, 91, 90, 111, 110, 109], [109, 108, 91, 90, 111, 110], [109, 108, 91, 90, 111, 110], [110, 109, 108, 91, 90, 111], [110, 109, 108, 91, 90, 111], [111, 90, 91, 92, 93, 89], [114, 112, 113, 117, 116, 124], [115, 114, 112, 113, 117, 116], [115, 114, 112, 113, 117, 116], [116, 124, 123, 122, 121, 117], [116, 124, 123, 122, 121, 117], [117, 113, 112, 114, 115, 116], [117, 113, 112, 114, 115, 116], [118, 113, 112, 114, 115, 116], [119, 118, 113, 112, 114, 115], [120, 119, 118, 113, 112, 114], [121, 117, 113, 112, 114, 115], [122, 121, 117, 113, 112, 114], [125, 126, 127, 128, 123, 124], [125, 126, 127, 128, 123, 124], [128, 123, 124, 116, 115, 114], [130, 129, 107, 106, 104, 105], [131, 122, 121, 117, 113, 112], [132, 120, 119, 118, 113, 112], [133, 131, 122, 121, 117, 113], [134, 132, 120, 119, 118, 113], [135, 134, 132, 120, 119, 118], [138, 137, 136, 135, 134, 132], [139, 118, 113, 112, 114, 115], [141, 140, 142, 143, 144, 145], [142, 140, 141, 146, 147, 164], [143, 142, 140, 141, 146, 147], [144, 143, 142, 140, 141, 146], [145, 149, 150, 151, 152, 144], [145, 149, 150, 151, 152, 144], [146, 141, 140, 142, 143, 144], [147, 164, 163, 162, 160, 148], [147, 164, 163, 162, 160, 148], [149, 150, 151, 152, 144, 143], [152, 144, 143, 142, 140, 141], [153, 152, 144, 143, 142, 140], [154, 153, 152, 144, 143, 142], [155, 137, 136, 135, 134, 132], [156, 151, 150, 149, 145, 141], [157, 135, 134, 132, 120, 119], [158, 157, 135, 134, 132, 120], [159, 161, 160, 148, 149, 150], [162, 163, 164, 165, 15, 14], [165, 15, 14, 13, 12, 4]]
```
EDIT: I just perceived that I get all classes of symmetry for each cycle, but I think it is better to remove this in postprocessing. Transforming each cycle in a `Set` of `edges` and calling `unique` should reduce the cycle list to only one representation of each cycle.
---
### Author:  [@Leticia-maria](https://discourse.julialang.org/u/Leticia-maria)
#### Post date: [February 10, 2022, 3:30pm UTC](https://discourse.julialang.org/t/add-elements-to-tuples-or-arrays/75885/29 "2022-02-10T15:30:31Z")
> [@Henrique\_Becker](#):
>
> `cycles_base_0 = map(vertices -> vertices .- 1, cycles_base_1)`
Hey, @Henrique_Becker thank you for rewriting the code:
```julia
using MolecularGraph
using LinearAlgebra
using Statistics
using DataStructures
function compound(SMILES::String)
mol = smilestomol(SMILES)
mol_ed = [] # molecule_edges extracted from MolecularGraph
i_vert = []
j_vert = []
for edge in mol.edges
push!(mol_ed, edge, reverse(edge))
end
for ed in mol_ed
push!(i_vert, ed[1])
push!(j_vert, ed[2])
end
neighbour_list = tuple(i_vert, j_vert)
return neighbour_list
end
function edges2neighbors(xs, ys)
max_vertex = max(maximum(xs), maximum(ys))
neighbours = Vector{Int}[Int[] for i in 1:max_vertex]
for (i_v, j_v) in zip(xs, ys)
push!(neighbours[i_v], j_v)
end
return neighbours
end
a = edges2neighbors(compound("C1=CC=CC=C1")[1], compound("C1=CC=CC=C1")[2])
print(a)
function inner_dfs_cycle_detection!(cycles, candidate, neighbours, cycle_length)
@assert length(candidate) <= cycle_length
for next_vertex in neighbours[last(candidate)]
if next_vertex == first(candidate)
if length(candidate) < cycle_length
continue
else
push!(cycles, copy(candidate))
end
elseif next_vertex in candidate
# Do not cycle back to the middle of candidate.
continue
elseif length(candidate) < cycle_length
# If the candidate does not have a subcycle and it is smaller
# than the desired cycle length, then recurse.
push!(candidate, next_vertex)
inner_dfs_cycle_detection!(cycles, candidate, neighbours, cycle_length)
end
end
return
end
function dfs_cycle_detection(neighbours, cycle_length)
cycles = Vector{eltype(neighbours)}()
for initial_vertex in eachindex(neighbours)
inner_dfs_cycle_detection!(cycles, [initial_vertex], neighbours, cycle_length)
end
return cycles
end
cycles_base_1 = dfs_cycle_detection(a, 6)
print(cycles_base_1)
# output: [[1, 2, 3, 4, 5, 6], [2, 1, 6, 5, 4, 3], [3, 2, 1, 6, 5, 4], [3, 2, 1, 6, 5, 4], [4, 3, 2, 1, 6, 5], [4, 3, 2, 1, 6, 5], [5, 4, 3, 2, 1, 6], [5, 4, 3, 2, 1, 6], [6, 5, 4, 3, 2, 1], [6, 5, 4, 3, 2, 1]]
```
I have added the `compound` function, that converts SMILES to a list of edges. But now, I have another issue: this code you wrote returns the same cycle with different orders, as you can see in the output:
```julia
[[1, 2, 3, 4, 5, 6], [2, 1, 6, 5, 4, 3], [3, 2, 1, 6, 5, 4], [3, 2, 1, 6, 5, 4], [4, 3, 2, 1, 6, 5], [4, 3, 2, 1, 6, 5], [5, 4, 3, 2, 1, 6], [5, 4, 3, 2, 1, 6], [6, 5, 4, 3, 2, 1], [6, 5, 4, 3, 2, 1]]
```
I would like to return an array with only different cycles, because I’m dealing with molecules, which are instances of undirected graphs.
---
### Author:  [@Leticia-maria](https://discourse.julialang.org/u/Leticia-maria)
#### Post date: [February 10, 2022, 3:36pm UTC](https://discourse.julialang.org/t/add-elements-to-tuples-or-arrays/75885/30 "2022-02-10T15:36:57Z")
And I would like to identify cycles with less than 4 vertices
---
### Author:  [@Henrique\_Becker](https://discourse.julialang.org/u/Henrique_Becker)
#### Post date: [February 11, 2022, 1:22am UTC](https://discourse.julialang.org/t/add-elements-to-tuples-or-arrays/75885/31 "2022-02-11T01:22:48Z")
I had already mentioned how to only have unique cycles.
> [@Henrique\_Becker](#):
>
> Transforming each cycle in a `Set` of `edges` and calling `unique` should reduce the cycle list to only one representation of each cycle.
The following code solve the uniqueness problem:
```julia
function unique_cycles(cycles)
(x -> first.(x)).(unique!(map(c -> Set(c .=> circshift(c, 1)), cycles)))
end
unique_cycles_base_0 = unique_cycles(cycles_base_0)
println(unique_cycles_base_0)
```
> [@Leticia-maria](#):
>
> And I would like to identify cycles with less than 4 vertices
Less than 6 vertices you mean? Or between 4 and 6 vertices?
The part of the code that needs to be edited is:
```julia
function inner_dfs_cycle_detection!(cycles, candidate, neighbors, cycle_length)
@assert length(candidate) <= cycle_length
for next_vertex in neighbors[last(candidate)]
if next_vertex == first(candidate)
# The cycle needs to have exactly length 6?
if length(candidate) < cycle_length
continue
else
push!(cycles, copy(candidate))
end
[...]
```
The last `if` clause before `continue` indicates the condition for **ignoring** a cycle. If you want every cycle larger than a self-loop (i.e., single vertice loops, not sure if they are possible there) then just change from `length(candidate) < cycle_length` to `length(candidate) < 1`. The parameter `cycle_length` will keep defining the maximum cycle size.
---
### Author:  [@Ken\_Williams](https://discourse.julialang.org/u/Ken_Williams)
#### Post date: [June 24, 2025, 8:43pm UTC](https://discourse.julialang.org/t/add-elements-to-tuples-or-arrays/75885/32 "2025-06-24T20:43:00Z")
I am surprised nobody mentioned the straightforward solution that does exactly what @Leticia-maria asked for - did `vcat()` not exist in 2022?
```julia
julia> a = [1,2,3];
julia> vcat(a, 4)
4-element Vector{Int64}:
1
2
3
4
```
---
### Author:  [@stevengj](https://discourse.julialang.org/u/stevengj)
#### Post date: [June 24, 2025, 9:39pm UTC](https://discourse.julialang.org/t/add-elements-to-tuples-or-arrays/75885/33 "2025-06-24T21:39:03Z")
> [@Ken\_Williams](#):
>
> I am surprised nobody mentioned the straightforward solution that does exactly what @Leticia-maria asked for - did `vcat()` not exist in 2022?
`vcat` was mentioned above ([Add elements to tuples or arrays - #6 by Seif\_Shebl](https://discourse.julialang.org/t/add-elements-to-tuples-or-arrays/75885/6)), but is less efficient than `push!` or `append!` because it allocates a brand new array rather than growing an existing one. (Also the thread got complicated because the OP was really implicitly asking about something else entirely: [Add elements to tuples or arrays - #13 by Henrique\_Becker](https://discourse.julialang.org/t/add-elements-to-tuples-or-arrays/75885/13))
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