Support 2d sources and sources away from the origin

docs/ess/odin.ipynb

@@ -41,7 +41,7 @@
    "metadata": {},
    "outputs": [],
    "source": [
-    "source = tof.Source(facility=\"ess\", neutrons=500_000, pulses=4)\n",
+    "source = tof.Source(facility=\"ess-odin\", neutrons=500_000, pulses=4)\n",
     "source.plot()"
    ]
   },

docs/sources.ipynb

@@ -108,6 +108,15 @@
     "\n",
     "We first show how to create flat time and wavelength distributions.\n",
     "\n",
+    "<div class=\"alert alert-warning\">\n",
+    "\n",
+    "**Changes in version 25.12.0**\n",
+    "\n",
+    "Linear interpolation between points in a source profile is no longer performed automatically.\n",
+    "\n",
+    "You will now need to create enough sampling points (see the use of `linspace` with 100 points below) in the distribution for good results.\n",
+    "    \n",
+    "</div>\n",
     "\n",
     "To create a pulse with 1 million neutrons, uniformly distributed in the ranges of 1-3 ms for birth times,\n",
     "and 1-10 Å for wavelengths, we write:"
@@ -120,13 +129,13 @@
    "metadata": {},
    "outputs": [],
    "source": [
-    "birth_time = sc.array(dims=['birth_time'], values=[1.0, 3.0], unit='ms')\n",
+    "birth_time = sc.linspace('birth_time', 1.0, 3.0, 100, unit='ms')\n",
     "p_time = sc.DataArray(\n",
     "    data=sc.ones(sizes=birth_time.sizes),\n",
     "    coords={'birth_time': birth_time},\n",
     ")\n",
     "\n",
-    "wavelength = sc.array(dims=['wavelength'], values=[1.0, 10.0], unit='angstrom')\n",
+    "wavelength = sc.linspace('wavelength', 1.0, 10.0, 100, unit='angstrom')\n",
     "p_wav = sc.DataArray(\n",
     "    data=sc.ones(sizes=wavelength.sizes),\n",
     "    coords={'wavelength': wavelength},\n",
@@ -152,8 +161,17 @@
     "The array values represent the probabilities, while the associated coordinates represent the values to be sampled from.\n",
     "\n",
     "As an example, we create a triangular distribution for the neutron birth times,\n",
-    "and a linearly increasing distribution for the neutron wavelengths\n",
-    "(note that internally a linear interpolation is performed on the original data)."
+    "and a linearly increasing distribution for the neutron wavelengths.\n",
+    "\n",
+    "<div class=\"alert alert-warning\">\n",
+    "\n",
+    "**Changes in version 25.12.0**\n",
+    "\n",
+    "Linear interpolation between points in a source profile is no longer performed automatically.\n",
+    "\n",
+    "You will now need to create enough sampling points (see the use of `linspace` with 30 points below) in the distribution for good results.\n",
+    "    \n",
+    "</div>"
    ]
   },
   {
@@ -164,15 +182,14 @@
    "outputs": [],
    "source": [
     "v = np.arange(30.0)\n",
+    "n = len(v) * 2\n",
     "p_time = sc.DataArray(\n",
     "    data=sc.array(dims=['birth_time'], values=np.concatenate([v, v[::-1]])),\n",
-    "    coords={'birth_time': sc.linspace('birth_time', 0.1, 6.0, len(v) * 2, unit='ms')},\n",
+    "    coords={'birth_time': sc.linspace('birth_time', 0.1, 6.0, n, unit='ms')},\n",
     ")\n",
     "p_wav = sc.DataArray(\n",
-    "    data=sc.array(dims=['wavelength'], values=[1.0, 4.0]),\n",
-    "    coords={\n",
-    "        'wavelength': sc.array(dims=['wavelength'], values=[1.0, 4.0], unit='angstrom')\n",
-    "    },\n",
+    "    data=sc.linspace('wavelength', 1.0, 4.0, n),\n",
+    "    coords={'wavelength': sc.linspace('wavelength', 1.0, 4.0, n, unit='angstrom')},\n",
     ")\n",
     "\n",
     "source = tof.Source.from_distribution(neutrons=200_000, p_time=p_time, p_wav=p_wav)\n",
@@ -186,13 +203,56 @@
    "source": [
     "Note that the time and wavelength distributions are independent;\n",
     "a neutron with a randomly selected birth time from `p_time` can adopt any wavelength in `p_wav`\n",
-    "(in other words, the two distributions are simply broadcast into a square 2D parameter space)."
+    "(in other words, the two distributions are simply broadcast into a square 2D parameter space).\n",
+    "\n",
+    "### 2D distributions\n",
+    "\n",
+    "You can also specify a single `p` data array which represents a 2D probability distribution:"
    ]
   },
   {
-   "cell_type": "markdown",
+   "cell_type": "code",
+   "execution_count": null,
    "id": "13",
    "metadata": {},
+   "outputs": [],
+   "source": [
+    "y, x = np.indices((300, 300))\n",
+    "X, Y = x - 150, y - 150\n",
+    "t = np.pi / 4\n",
+    "a = np.exp(\n",
+    "    -(\n",
+    "        ((np.cos(t) * X + np.sin(t) * Y) / 80) ** 2\n",
+    "        + ((-np.sin(t) * X + np.cos(t) * Y) / 40) ** 2\n",
+    "    )\n",
+    ")\n",
+    "\n",
+    "p = sc.DataArray(\n",
+    "    data=sc.array(dims=['wavelength', 'birth_time'], values=a),\n",
+    "    coords={\n",
+    "        'birth_time': sc.linspace('birth_time', 0, 6000, a.shape[1], unit='us'),\n",
+    "        'wavelength': sc.linspace('wavelength', 0.2, 9.0, a.shape[0], unit='angstrom'),\n",
+    "    },\n",
+    ")\n",
+    "\n",
+    "p.plot()"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "id": "14",
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "source = tof.Source.from_distribution(neutrons=200_000, p=p)\n",
+    "source.plot()"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "id": "15",
+   "metadata": {},
    "source": [
     "## Specifying neutrons manually\n",
     "\n",
@@ -202,7 +262,7 @@
   {
    "cell_type": "code",
    "execution_count": null,
-   "id": "14",
+   "id": "16",
    "metadata": {},
    "outputs": [],
    "source": [
@@ -219,7 +279,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "15",
+   "id": "17",
    "metadata": {},
    "source": [
     "## Multiple pulses\n",
@@ -230,7 +290,7 @@
   {
    "cell_type": "code",
    "execution_count": null,
-   "id": "16",
+   "id": "18",
    "metadata": {},
    "outputs": [],
    "source": [
@@ -239,7 +299,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "17",
+   "id": "19",
    "metadata": {},
    "source": [
     "If a custom distribution is supplied, a frequency for the pulse repetition rate must be supplied:"
@@ -248,7 +308,7 @@
   {
    "cell_type": "code",
    "execution_count": null,
-   "id": "18",
+   "id": "20",
    "metadata": {},
    "outputs": [],
    "source": [
@@ -259,7 +319,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "19",
+   "id": "21",
    "metadata": {},
    "source": [
     "If a source was created from individual neutrons, the same neutrons will be repeated in all the pulses:"
@@ -268,7 +328,7 @@
   {
    "cell_type": "code",
    "execution_count": null,
-   "id": "20",
+   "id": "22",
    "metadata": {},
    "outputs": [],
    "source": [
@@ -293,7 +353,8 @@
    "mimetype": "text/x-python",
    "name": "python",
    "nbconvert_exporter": "python",
-   "pygments_lexer": "ipython3"
+   "pygments_lexer": "ipython3",
+   "version": "3.12.7"
   }
  },
  "nbformat": 4,

pyproject.toml

@@ -31,8 +31,8 @@ requires-python = ">=3.11"
 # Make sure to list one dependency per line.
 dependencies = [
   "plopp>=23.10.0",
+  "pooch>=1.5.0",
   "scipp>=24.11.0",
-  "scipy>=1.12.0",
   "lazy-loader>=0.3",
 ]
 

requirements/base.in

@@ -1,7 +1,7 @@
 
 # --- END OF CUSTOM SECTION ---
 # The following was generated by 'tox -e deps', DO NOT EDIT MANUALLY!
-plopp
-scipp
-scipy
-lazy-loader
+plopp>=23.10.0
+pooch>=1.5.0
+scipp>=24.11.0
+lazy-loader>=0.3

requirements/base.txt

@@ -1,16 +1,22 @@
-# SHA1:93efe7bb51c682462f1051ef5af0af230a7919ae
+# SHA1:57c5f034856b0519923827bc5b12ab41003445e1
 #
 # This file was generated by pip-compile-multi.
 # To update, run:
 #
 #    requirements upgrade
 #
+certifi==2025.11.12
+    # via requests
+charset-normalizer==3.4.4
+    # via requests
 contourpy==1.3.3
     # via matplotlib
 cycler==0.12.1
     # via matplotlib
 fonttools==4.60.1
     # via matplotlib
+idna==3.11
+    # via requests
 kiwisolver==1.4.9
     # via matplotlib
 lazy-loader==0.4
@@ -19,27 +25,33 @@ lazy-loader==0.4
     #   plopp
 matplotlib==3.10.7
     # via plopp
-numpy==2.3.4
+numpy==2.3.5
     # via
     #   contourpy
     #   matplotlib
     #   scipp
-    #   scipy
 packaging==25.0
     # via
     #   lazy-loader
     #   matplotlib
+    #   pooch
 pillow==12.0.0
     # via matplotlib
-plopp==25.10.0
+platformdirs==4.5.0
+    # via pooch
+plopp==25.11.0
+    # via -r base.in
+pooch==1.8.2
     # via -r base.in
 pyparsing==3.2.5
     # via matplotlib
 python-dateutil==2.9.0.post0
     # via matplotlib
+requests==2.32.5
+    # via pooch
 scipp==25.11.0
     # via -r base.in
-scipy==1.16.3
-    # via -r base.in
 six==1.17.0
     # via python-dateutil
+urllib3==2.5.0
+    # via requests

requirements/basetest.in

@@ -7,5 +7,5 @@
 # will not be touched by ``make_base.py``
 # --- END OF CUSTOM SECTION ---
 # The following was generated by 'tox -e deps', DO NOT EDIT MANUALLY!
-pytest
-scippneutron
+pytest>=8.0
+scippneutron>=24.12.0

requirements/basetest.txt

@@ -1,4 +1,4 @@
-# SHA1:ed95f3d9fbbb40522ea55cda7e22928120aae7db
+# SHA1:416b6c94ef7ae6bd7c585fc1a97de56b917092ee
 #
 # This file was generated by pip-compile-multi.
 # To update, run:
@@ -37,7 +37,7 @@ matplotlib==3.10.7
     #   plopp
 mpltoolbox==25.10.0
     # via scippneutron
-numpy==2.3.4
+numpy==2.3.5
     # via
     #   contourpy
     #   h5py
@@ -52,7 +52,7 @@ packaging==25.0
     #   pytest
 pillow==12.0.0
     # via matplotlib
-plopp==25.10.0
+plopp==25.11.0
     # via scippneutron
 pluggy==1.6.0
     # via pytest
@@ -64,20 +64,19 @@ pygments==2.19.2
     # via pytest
 pyparsing==3.2.5
     # via matplotlib
-pytest==9.0.0
+pytest==9.0.1
     # via -r basetest.in
 python-dateutil==2.9.0.post0
     # via
     #   matplotlib
     #   scippneutron
-    #   scippnexus
 scipp==25.11.0
     # via
     #   scippneutron
     #   scippnexus
 scippneutron==25.7.0
     # via -r basetest.in
-scippnexus==25.6.0
+scippnexus==25.11.0
     # via scippneutron
 scipy==1.16.3
     # via

requirements/ci.txt

@@ -5,9 +5,9 @@
 #
 #    requirements upgrade
 #
-cachetools==6.2.1
+cachetools==6.2.2
     # via tox
-certifi==2025.10.5
+certifi==2025.11.12
     # via requests
 chardet==5.2.0
     # via tox

requirements/dev.txt

@@ -26,7 +26,7 @@ async-lru==2.0.5
     # via jupyterlab
 cffi==2.0.0
     # via argon2-cffi-bindings
-click==8.3.0
+click==8.3.1
     # via
     #   pip-compile-multi
     #   pip-tools
@@ -69,7 +69,7 @@ jupyter-server==2.17.0
     #   notebook-shim
 jupyter-server-terminals==0.5.3
     # via jupyter-server
-jupyterlab==4.4.10
+jupyterlab==4.5.0
     # via -r dev.in
 jupyterlab-server==2.28.0
     # via jupyterlab
@@ -81,7 +81,7 @@ overrides==7.7.0
     # via jupyter-server
 pip-compile-multi==3.2.2
     # via -r dev.in
-pip-tools==7.5.1
+pip-tools==7.5.2
     # via pip-compile-multi
 plumbum==1.10.0
     # via copier