lineSliceAlong fails

[tpolong]

 var route = {
            "type": "Feature",
            "geometry": {
                "type": "LineString",
                "coordinates": [[112.2998991, 22.0126324], [112.2996097, 22.0134472], [112.2996597, 22.0133881], [112.2777231, 22.0164887], [112.2774728, 22.0166772], [112.2774033, 22.0165736], [112.2775611, 22.0164055], [112.2776283, 22.0161038], [112.2776846, 22.0163612], [112.2776739, 22.0163395], [112.2776479, 22.0163987], [112.2776427, 22.0162798], [112.2775763, 22.016116], [112.2777229, 22.0161367], [112.2777592, 22.0161772], [112.2777634, 22.0162569], [112.277711, 22.0162228], [112.2776429, 22.0159677], [112.2777159, 22.0164053], [112.2777012, 22.0164482], [112.2777467, 22.0159461], [112.2774918, 22.016228], [112.2777323, 22.0163755], [112.27788, 22.0156734], [112.2777364, 22.0161047], [112.2777321, 22.0154175], [112.2775976, 22.0159372], [112.2775141, 22.0164522], [112.2773987, 22.0163157], [112.2777456, 22.016317], [112.2777335, 22.0160323], [112.2776058, 22.0159735], [112.2776119, 22.0162441], [112.277613, 22.0162797], [112.2776901, 22.0159297], [112.2776718, 22.0159579], [112.2776664, 22.0160062], [112.2776555, 22.0160424], [112.2776822, 22.0163974], [112.2776653, 22.0165653], [112.277671, 22.0165485], [112.2776557, 22.0165534], [112.2776157, 22.0157634], [112.2777147, 22.0160169], [112.2777923, 22.0161012], [112.2777863, 22.0160907], [112.2777051, 22.016329], [112.2777147, 22.0162952], [112.2777142, 22.0162654], [112.2777091, 22.0162184], [112.2777293, 22.0155411], [112.2777934, 22.016181], [112.277763, 22.0163602], [112.2777463, 22.0162394], [112.2777951, 22.0166046], [112.2776927, 22.0162132], [112.2777378, 22.0165474], [112.2775909, 22.0162195], [112.2775837, 22.0163702], [112.2773571, 22.0163615], [112.2774887, 22.0162945], [112.2779636, 22.0155648], [112.2776821, 22.0153425], [112.2775655, 22.01528], [112.277327, 22.0165847], [112.2776053, 22.0159045], [112.2776661, 22.0159655], [112.2777093, 22.0158935], [112.2777605, 22.0160012], [112.2774871, 22.0163442], [112.2775043, 22.0159103], [112.2774271, 22.0161922], [112.2775719, 22.0157997], [112.2779507, 22.0161869], [112.2772691, 22.0158395], [112.2774603, 22.0160507], [112.2773284, 22.0161886], [112.2769806, 22.0162803], [112.277367, 22.0160714], [112.2774255, 22.0156315], [112.2773364, 22.0165652], [112.2779057, 22.0172664], [112.2773697, 22.0159611], [112.2775842, 22.0168184], [112.2771331, 22.0168276], [112.276935, 22.0170211], [112.2771452, 22.0167653], [112.2772963, 22.0167357], [112.2773487, 22.016833], [112.2771117, 22.0170429], [112.2772882, 22.0150137], [112.277676, 22.0157572], [112.2775809, 22.0157616], [112.2776087, 22.0151958], [112.2775472, 22.0157747], [112.2776357, 22.0154047], [112.2776435, 22.0164565], [112.2776643, 22.0169043], [112.2764386, 22.0158418], [112.2777676, 22.016478], [112.2777093, 22.0165748], [112.2777221, 22.016404], [112.2775944, 22.0157735], [112.2777799, 22.0157752], [112.2776128, 22.0154483], [112.2777016, 22.0151869], [112.2775887, 22.0153978], [112.2775413, 22.0154168], [112.2776436, 22.0155891], [112.277575, 22.0155052], [112.2776914, 22.0161053], [112.2774094, 22.0156116], [112.2773298, 22.0158133], [112.2773486, 22.0160223], [112.2773499, 22.0160166], [112.2773534, 22.0160091], [112.2773868, 22.01594], [112.2776449, 22.0154259], [112.2775975, 22.016411], [112.2777683, 22.0155985], [112.2777066, 22.0155994], [112.2776718, 22.0156146], [112.2776693, 22.0156116], [112.2776541, 22.0155184], [112.2776593, 22.0160912], [112.277661, 22.016092], [112.2778694, 22.0157039], [112.2779937, 22.0157449], [112.2777242, 22.0159336], [112.2777495, 22.016103], [112.2774126, 22.0164878], [112.2774447, 22.0164391], [112.2774575, 22.0164354], [112.2775494, 22.0164708], [112.2777794, 22.0165267], [112.2775416, 22.0161283], [112.2774464, 22.0163779], [112.2778153, 22.0165429], [112.2776616, 22.0162139], [112.2774604, 22.0162103], [112.2776942, 22.0160659], [112.2775707, 22.0163708], [112.2774991, 22.0160763], [112.2774355, 22.0162447], [112.2776771, 22.0160008], [112.2776718, 22.0160062], [112.277704, 22.015915], [112.2777063, 22.0159108], [112.2775323, 22.0164836], [112.2777955, 22.0167154], [112.2778581, 22.0175943], [112.2776463, 22.0159604], [112.27762, 22.0163717], [112.2775426, 22.0163401], [112.2775736, 22.0157782], [112.2776664, 22.0157741], [112.2776853, 22.0163118], [112.2777307, 22.0162768], [112.2775162, 22.0161832], [112.2776874, 22.0162421]]
            }
        }

when I use turf.lineSliceAlong(route,8.461539655960873,8.478462735272794,, {units: 'kilometers'})
There will have a mistake,
(Uncaught Error: coordinates must contain number).
Code return lineString(coords[coords.length - 1]) as a point ,but the point could not be a linestring

[dpmcmlxxvi]

@tpolong Looks like a bug. There's an edge case here. If the start point is exactly on the end point of the line, the line-slice-along function is attempting to return a line with only one point. There are two issues:

• A LineString must be two or more points.
• The helper function turf.lineString is being called with a coordinate instead of an array of coordinates.

The code fix is to either return a LineString with the end point repeated (the spec is unclear if this is a valid line) or disallow this case. I think the first is fine.

In the meantime, you can test for this condition by checking the turf.length(route) < startDist before calling slice.

[tpolong]

@dpmcmlxxvi The turf.linechunk function also uses the line-slice-along function ,but it doesn't test for this condition by checking the turf.length(route) < startDist before calling slice.( in the sliceLineSegments function )

[dpmcmlxxvi]

@tpolong It doesn't look like the turf.lineChunk needs to test for that condition. The line is divided into segments of equal length, so the starting point can't be on the line's end-point.

[tpolong]

@dpmcmlxxvi var route = {
"type": "Feature",
"geometry": {
"type": "LineString",
"coordinates": [[70.2998991, 20.0126324], [70.2996097, 20.0134472], [70.2996597, 20.0133881], [70.2777231, 20.0164887], [70.2774728, 20.0166772], [70.2774033, 20.0165736], [70.2775611, 20.0164055], [70.2776283, 20.0161038], [70.2776846, 20.0163612], [70.2776739, 20.0163395], [70.2776479, 20.0163987], [70.2776427, 20.0162798], [70.2775763, 20.016116], [70.2777209, 20.0161367], [70.2777592, 20.0161772], [70.2777634, 20.0162569], [70.277711, 20.0162028], [70.2776429, 20.0159677], [70.2777159, 20.0164053], [70.2777012, 20.0164482], [70.2777467, 20.0159461], [70.2774918, 20.016208], [70.2777323, 20.0163755], [70.27788, 20.0156734], [70.2777364, 20.0161047], [70.2777321, 20.0154175], [70.2775976, 20.0159372], [70.2775141, 20.0164520], [70.2773987, 20.0163157], [70.2777456, 20.016317], [70.2777335, 20.0160323], [70.2776058, 20.0159735], [70.2776119, 20.0162441], [70.277613, 20.0162797], [70.2776901, 20.0159297], [70.2776718, 20.0159579], [70.2776664, 20.0160062], [70.2776555, 20.0160424], [70.2776820, 20.0163974], [70.2776653, 20.0165653], [70.277671, 20.0165485], [70.2776557, 20.0165534], [70.2776157, 20.0157634], [70.2777147, 20.0160169], [70.2777923, 20.0161012], [70.2777863, 20.0160907], [70.2777051, 20.016329], [70.2777147, 20.0162952], [70.2777142, 20.0162654], [70.2777091, 20.0162184], [70.2777293, 20.0155411], [70.2777934, 20.016181], [70.277763, 20.0163602], [70.2777463, 20.0162394], [70.2777951, 20.0166046], [70.2776927, 20.0162132], [70.2777378, 20.0165474], [70.2775909, 20.0162195], [70.2775837, 20.0163702], [70.2773571, 20.0163615], [70.2774887, 20.0162945], [70.2779636, 20.0155648], [70.2776821, 20.0153425], [70.2775655, 20.01528], [70.277327, 20.0165847], [70.2776053, 20.0159045], [70.2776661, 20.0159655], [70.2777093, 20.0158935], [70.2777605, 20.0160012], [70.2774871, 20.0163442], [70.2775043, 20.0159103], [70.2774271, 20.0161920], [70.2775719, 20.0157997], [70.2779507, 20.0161869], [70.2772691, 20.0158395], [70.2774603, 20.0160507], [70.2773284, 20.0161886], [70.2769806, 20.0162803], [70.277367, 20.0160714], [70.2774255, 20.0156315], [70.2773364, 20.0165652], [70.2779057, 20.0172664], [70.2773697, 20.0159611], [70.2775842, 20.0168184], [70.2771331, 20.0168276], [70.276935, 20.0170211], [70.2771452, 20.0167653], [70.2772963, 20.0167357], [70.2773487, 20.016833], [70.2771117, 20.0170429], [70.2772882, 20.0150137], [70.277676, 20.0157572], [70.2775809, 20.0157616], [70.2776087, 20.0151958], [70.2775472, 20.0157747], [70.2776357, 20.0154047], [70.2776435, 20.0164565], [70.2776643, 20.0169043], [70.2764386, 20.0158418], [70.2777676, 20.016478], [70.2777093, 20.0165748], [70.2777201, 20.016404], [70.2775944, 20.0157735], [70.2777799, 20.0157752], [70.2776128, 20.0154483], [70.2777016, 20.0151869], [70.2775887, 20.0153978], [70.2775413, 20.0154168], [70.2776436, 20.0155891], [70.277575, 20.0155052], [70.2776914, 20.0161053], [70.2774094, 20.0156116], [70.2773298, 20.0158133], [70.2773486, 20.0160203], [70.2773499, 20.0160166], [70.2773534, 20.0160091], [70.2773868, 20.01594], [70.2776449, 20.0154259], [70.2775975, 20.016411], [70.2777683, 20.0155985], [70.2777066, 20.0155994], [70.2776718, 20.0156146], [70.2776693, 20.0156116], [70.2776541, 20.0155184], [70.2776593, 20.0160912], [70.277661, 20.016092], [70.2778694, 20.0157039], [70.2779937, 20.0157449], [70.2777242, 20.0159336], [70.2777495, 20.016103], [70.2774126, 20.0164878], [70.2774447, 20.0164391], [70.2774575, 20.0164354], [70.2775494, 20.0164708], [70.2777794, 20.0165267], [70.2775416, 20.0161283], [70.2774464, 20.0163779], [70.2778153, 20.0165429], [70.2776616, 20.0162139], [70.2774604, 20.0162103], [70.2776942, 20.0160659], [70.2775707, 20.0163708], [70.2774991, 20.0160763], [70.2774355, 20.0162447], [70.2776771, 20.0160008], [70.2776718, 20.0160062], [70.277704, 20.015915], [70.2777063, 20.0159108], [70.2775323, 20.0164836], [70.2777955, 20.0167154], [70.2778581, 20.0175943], [70.2776463, 20.0159604], [70.27762, 20.0163717], [70.2775426, 20.0163401], [70.2775736, 20.0157782], [70.2776664, 20.0157741], [70.2776853, 20.0163118], [70.2777307, 20.0162768], [70.2775162, 20.0161832], [70.2776874, 20.0162421]]
}
}

    var lineDistance = turf.lineDistance(route, { units: 'kilometers' });
var nstep = 500;
    var nDistance = lineDistance / nstep;
var chunk = turf.lineChunk(route ,nDistance, {units: 'kilometers'})

If numberOfSegments is integer, no need to plus 1.In the case numberOfSegments pluses 1,so the code will have errors

[dpmcmlxxvi]

@tpolong This looks like a different bug due numerical precision. Please submit as a different issue.

[dpmcmlxxvi]

Looks like a duplicate of #1577