Maybe Dask not necessary

astropy · Feb 10, 2020 · 6d4fe3d · 6d4fe3d
1 parent 4dd9903
commit 6d4fe3d
Showing 1 changed file with 14 additions and 15 deletions.
diff --git a/example_notebooks/cube_4d.ipynb b/example_notebooks/cube_4d.ipynb
@@ -15,6 +15,7 @@
    "metadata": {},
    "outputs": [],
    "source": [
+    "from astropy import units as u\n",
     "from astropy.nddata import NDData\n",
     "from astropy.wcs import WCS\n",
     "from ginga.misc.log import get_logger\n",
@@ -140,10 +141,13 @@
     "import numpy as np\n",
     "\n",
     "pf = None  # Not using FITS file pointer\n",
-    "cube4d = np.random.random((2, 5, 100, 200))\n",
+    "cube4d = np.random.random((2, 5, 100, 200)).astype(np.float32)\n",
     "\n",
     "# Convert to NDData.\n",
-    "im = NDData(cube4d, wcs=WCS(naxis=4))"
+    "im = NDData(cube4d, wcs=WCS(naxis=4))\n",
+    "\n",
+    "# Memory footprint\n",
+    "print((cube4d.size * 32 * u.bit).to(u.kB))"
    ]
   },
   {
@@ -152,9 +156,7 @@
    "source": [
     "**--- OR ---**\n",
     "\n",
-    "Load an existing data cube.\n",
-    "\n",
-    "Dask support requires https://github.com/ejeschke/ginga/pull/805."
+    "Load an existing data cube."
    ]
   },
   {
@@ -163,21 +165,22 @@
    "metadata": {},
    "outputs": [],
    "source": [
-    "import dask.array as da\n",
     "from astropy.io import fits\n",
     "\n",
-    "# This is a large cube that is 6GB.\n",
+    "# This is a large cube.\n",
     "filename = '/redkeep/ironthrone/ssb/stginga/test_data/NRCN815A_LIN_20160115_uncal.fits'\n",
     "pf = fits.open(filename, memmap=True)\n",
     "\n",
     "# There is no WCS assigned for UNCAL file yet.\n",
     "# This is a dummy WCS.\n",
     "im_wcs = WCS(pf[1].header)\n",
     "\n",
-    "# Convert to NDData that wraps a Dask array.\n",
-    "# Must provide Dask with a name to avoid hashing.\n",
+    "# Pass memmap-ed FITS data into NDData.\n",
     "# Shape is (1, 190, 2048, 2048)\n",
-    "im = NDData(da.from_array(pf[1].data, name='nircam_sci'), wcs=im_wcs)"
+    "im = NDData(pf[1].data, wcs=im_wcs)\n",
+    "\n",
+    "# Memory footprint\n",
+    "print((im.data.size * 32 * u.bit).to(u.GB))"
    ]
   },
   {
@@ -209,8 +212,6 @@
    "metadata": {},
    "outputs": [],
    "source": [
-    "# Loading a fake WCS into widget sometimes gives error.\n",
-    "# Try reloading before giving up.\n",
     "w.load_nddata(im)"
    ]
   },
@@ -298,9 +299,7 @@
    "cell_type": "markdown",
    "metadata": {},
    "source": [
-    "Display the widgets.\n",
-    "\n",
-    "*Dev notes: Seems to be a few seconds lag when clicking on new region far away from the current one on the image when testing with 6GB JWST/NIRCam \"uncal\" cube. This is probably due to Dask loading new chunks for processing. At least it did not try to load all the 6GB of data, which is a good sign.*"
+    "Display the widgets."
    ]
   },
   {