django/django · error · TypeError

Must set coordinate with a sequence (list, tuple, or numpy a

Error message

Must set coordinate with a sequence (list, tuple, or numpy array).

What it means

Raised in GEOSCoordSeq.__setitem__ when the value being assigned to a coordinate index is not a list, tuple, or numpy.ndarray. Coordinate slots must receive a sequence of ordinates (e.g. (x,y) or [x,y,z]) so the setter can unpack them; scalars, strings, or generators are rejected. numpy is optional, so ndarray is only accepted if numpy is installed.

Source

Thrown at django/contrib/gis/geos/coordseq.py:56

    def __str__(self):
        "Return the string representation of the coordinate sequence."
        return str(self.tuple)

    def __getitem__(self, index):
        "Return the coordinate sequence value at the given index."
        self._checkindex(index)
        return self._point_getter(index)

    def __setitem__(self, index, value):
        "Set the coordinate sequence value at the given index."
        # Checking the input value
        if isinstance(value, (list, tuple)):
            pass
        elif numpy and isinstance(value, numpy.ndarray):
            pass
        else:
            raise TypeError(
                "Must set coordinate with a sequence (list, tuple, or numpy array)."
            )
        # Checking the dims of the input
        if self.dims == 3 and self._z:
            n_args = 3
            point_setter = self._set_point_3d
        elif self.dims == 3 and self.hasm:
            n_args = 3
            point_setter = self._set_point_3d_m
        elif self.dims == 4 and self._z and self.hasm:
            n_args = 4
            point_setter = self._set_point_4d
        else:
            n_args = 2
            point_setter = self._set_point_2d
        if len(value) != n_args:
            raise TypeError("Dimension of value does not match.")
        self._checkindex(index)

View on GitHub (pinned to ae25a40be0)

Solutions

Assign a list/tuple: seq[i] = (x, y) or [x, y, z]
For numpy users: seq[i] = np.array([x, y])
Use setOrdinate(dim, index, value) to set a single ordinate instead

Example fix

// before
seq[0] = 5.0
seq[0] = '10 20'
// after
seq[0] = (10, 20)
# or single ordinate
seq.setX(0, 10)

Defensive patterns

Strategy: type-guard

Validate before calling

from django.contrib.gis.shortcuts import numpy

def coerce_coord_value(v):
    if isinstance(v, (list, tuple)):
        return v
    if numpy and isinstance(v, numpy.ndarray):
        return v
    raise TypeError('coordinate must be list/tuple/ndarray')

Type guard

from django.contrib.gis.shortcuts import numpy

def is_coord_sequence(v) -> bool:
    return isinstance(v, (list, tuple)) or (numpy is not None and isinstance(v, numpy.ndarray))

Try / catch

try:
    seq[i] = value
except TypeError as e:
    if 'Must set coordinate' in str(e):
        seq[i] = tuple(value)
    raise

Prevention

Always assign (x, y) or [x, y, z]
Use setX/setY/setZ for single ordinates
Avoid passing parsed strings without splitting

When it happens

Trigger: Doing seq[i] = 5.0 (scalar), seq[i] = '5,6' (string), seq[i] = generator, or seq[i] = some_object. Also triggered when assigning a single ordinate where a tuple was expected.

Common situations: Treating a coordinate slot as a scalar field; passing coordinates parsed from a CSV string without splitting; forgetting to wrap lon/lat in a tuple.

Related errors

AI-assisted analysis of django/django@ae25a40be0 (2026-08-06). Data as JSON: /api/errors/45eed89c7e599347. Report an issue: GitHub.