Animated Charts.ipynb

{
 "cells": [
  {
   "cell_type": "markdown",
   "source": [
    "# Animated charts\n",
    "\n",
    "Often times its important to be able to see a multidimensional data over time\n",
    "or another linear dimension. We can help our brains out by making a video!\n",
    "\n",
    "To do this we'll use a pretty contrived example to:\n",
    "1. Use matplotlib to output individual frames\n",
    "2. Combine the frames with ffmpeg"
   ],
   "metadata": {}
  },
  {
   "cell_type": "code",
   "execution_count": 17,
   "source": [
    "# Ensure we have an output directory\n",
    "! [ ! -d \"output\" ] && mkdir output"
   ],
   "outputs": [],
   "metadata": {}
  },
  {
   "cell_type": "code",
   "execution_count": 18,
   "source": [
    "import matplotlib.pyplot as plt\n",
    "import numpy as np\n",
    "\n",
    "\n",
    "def write_img(frame: int):\n",
    "    fig, axis = plt.subplots(1, 1, figsize=(4, 4))\n",
    "    plt.suptitle(f\"Frame {frame:04d}\")\n",
    "    x = np.linspace(0, 2 * np.pi, 100)\n",
    "    y = np.sin(frame / np.pi + x)\n",
    "    axis.plot(x, y)\n",
    "    plt.savefig(f\"output/{frame:04d}.png\", dpi=400)\n",
    "    fig.clf()\n",
    "    plt.close()\n",
    "\n",
    "\n",
    "for i in range(100):\n",
    "    write_img(i)\n"
   ],
   "outputs": [],
   "metadata": {}
  },
  {
   "cell_type": "code",
   "execution_count": 20,
   "source": [
    "!ffmpeg -y -r 60 -f image2 -s 1600x1600 -i output/%04d.png -crf 25 -pix_fmt yuv420p output/animated-chart.mp4"
   ],
   "outputs": [
    {
     "output_type": "stream",
     "name": "stdout",
     "text": [
      "ffmpeg version 4.4 Copyright (c) 2000-2021 the FFmpeg developers\n",
      "  built with Apple clang version 12.0.5 (clang-1205.0.22.9)\n",
      "  configuration: --prefix=/usr/local/Cellar/ffmpeg/4.4_2 --enable-shared --enable-pthreads --enable-version3 --cc=clang --host-cflags= --host-ldflags= --enable-ffplay --enable-gnutls --enable-gpl --enable-libaom --enable-libbluray --enable-libdav1d --enable-libmp3lame --enable-libopus --enable-librav1e --enable-librubberband --enable-libsnappy --enable-libsrt --enable-libtesseract --enable-libtheora --enable-libvidstab --enable-libvorbis --enable-libvpx --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxml2 --enable-libxvid --enable-lzma --enable-libfontconfig --enable-libfreetype --enable-frei0r --enable-libass --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg --enable-libspeex --enable-libsoxr --enable-libzmq --enable-libzimg --disable-libjack --disable-indev=jack --enable-avresample --enable-videotoolbox\n",
      "  libavutil      56. 70.100 / 56. 70.100\n",
      "  libavcodec     58.134.100 / 58.134.100\n",
      "  libavformat    58. 76.100 / 58. 76.100\n",
      "  libavdevice    58. 13.100 / 58. 13.100\n",
      "  libavfilter     7.110.100 /  7.110.100\n",
      "  libavresample   4.  0.  0 /  4.  0.  0\n",
      "  libswscale      5.  9.100 /  5.  9.100\n",
      "  libswresample   3.  9.100 /  3.  9.100\n",
      "  libpostproc    55.  9.100 / 55.  9.100\n",
      "Input #0, image2, from 'output/%04d.png':\n",
      "  Duration: 00:00:01.67, start: 0.000000, bitrate: N/A\n",
      "  Stream #0:0: Video: png, rgba(pc), 1600x1600 [SAR 15748:15748 DAR 1:1], 60 fps, 60 tbr, 60 tbn, 60 tbc\n",
      "Stream mapping:\n",
      "  Stream #0:0 -> #0:0 (png (native) -> h264 (libx264))\n",
      "Press [q] to stop, [?] for help\n",
      "\u001b[1;36m[libx264 @ 0x7fb3d280d400] \u001b[0musing SAR=1/1\n",
      "\u001b[1;36m[libx264 @ 0x7fb3d280d400] \u001b[0musing cpu capabilities: MMX2 SSE2Fast SSSE3 SSE4.2 AVX FMA3 BMI2 AVX2\n",
      "\u001b[1;36m[libx264 @ 0x7fb3d280d400] \u001b[0mprofile High, level 5.1, 4:2:0, 8-bit\n",
      "\u001b[1;36m[libx264 @ 0x7fb3d280d400] \u001b[0m264 - core 163 r3060 5db6aa6 - H.264/MPEG-4 AVC codec - Copyleft 2003-2021 - http://www.videolan.org/x264.html - options: cabac=1 ref=3 deblock=1:0:0 analyse=0x3:0x113 me=hex subme=7 psy=1 psy_rd=1.00:0.00 mixed_ref=1 me_range=16 chroma_me=1 trellis=1 8x8dct=1 cqm=0 deadzone=21,11 fast_pskip=1 chroma_qp_offset=-2 threads=18 lookahead_threads=3 sliced_threads=0 nr=0 decimate=1 interlaced=0 bluray_compat=0 constrained_intra=0 bframes=3 b_pyramid=2 b_adapt=1 b_bias=0 direct=1 weightb=1 open_gop=0 weightp=2 keyint=250 keyint_min=25 scenecut=40 intra_refresh=0 rc_lookahead=40 rc=crf mbtree=1 crf=25.0 qcomp=0.60 qpmin=0 qpmax=69 qpstep=4 ip_ratio=1.40 aq=1:1.00\n",
      "Output #0, mp4, to 'output/animated-chart.mp4':\n",
      "  Metadata:\n",
      "    encoder         : Lavf58.76.100\n",
      "  Stream #0:0: Video: h264 (avc1 / 0x31637661), yuv420p(tv, progressive), 1600x1600 [SAR 1:1 DAR 1:1], q=2-31, 60 fps, 15360 tbn\n",
      "    Metadata:\n",
      "      encoder         : Lavc58.134.100 libx264\n",
      "    Side data:\n",
      "      cpb: bitrate max/min/avg: 0/0/0 buffer size: 0 vbv_delay: N/A\n",
      "frame=  100 fps= 56 q=-1.0 Lsize=     295kB time=00:00:01.61 bitrate=1494.9kbits/s speed=0.899x    \n",
      "video:294kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 0.426828%\n",
      "\u001b[1;36m[libx264 @ 0x7fb3d280d400] \u001b[0mframe I:1     Avg QP:26.32  size: 18243\n",
      "\u001b[1;36m[libx264 @ 0x7fb3d280d400] \u001b[0mframe P:99    Avg QP:36.29  size:  2847\n",
      "\u001b[1;36m[libx264 @ 0x7fb3d280d400] \u001b[0mmb I  I16..4: 33.0% 61.9%  5.1%\n",
      "\u001b[1;36m[libx264 @ 0x7fb3d280d400] \u001b[0mmb P  I16..4:  0.2%  2.5%  0.9%  P16..4:  2.3%  0.3%  0.1%  0.0%  0.0%    skip:93.8%\n",
      "\u001b[1;36m[libx264 @ 0x7fb3d280d400] \u001b[0m8x8 transform intra:68.0% inter:15.9%\n",
      "\u001b[1;36m[libx264 @ 0x7fb3d280d400] \u001b[0mcoded y,uvDC,uvAC intra: 15.2% 23.8% 23.6% inter: 0.1% 0.2% 0.0%\n",
      "\u001b[1;36m[libx264 @ 0x7fb3d280d400] \u001b[0mi16 v,h,dc,p: 56% 41%  3%  0%\n",
      "\u001b[1;36m[libx264 @ 0x7fb3d280d400] \u001b[0mi8 v,h,dc,ddl,ddr,vr,hd,vl,hu: 14%  2% 78%  1%  0%  1%  0%  4%  0%\n",
      "\u001b[1;36m[libx264 @ 0x7fb3d280d400] \u001b[0mi4 v,h,dc,ddl,ddr,vr,hd,vl,hu: 11%  5% 40% 12%  1%  4%  1% 25%  1%\n",
      "\u001b[1;36m[libx264 @ 0x7fb3d280d400] \u001b[0mi8c dc,h,v,p: 87%  2%  7%  4%\n",
      "\u001b[1;36m[libx264 @ 0x7fb3d280d400] \u001b[0mWeighted P-Frames: Y:0.0% UV:0.0%\n",
      "\u001b[1;36m[libx264 @ 0x7fb3d280d400] \u001b[0mref P L0: 64.2%  2.7% 29.5%  3.5%\n",
      "\u001b[1;36m[libx264 @ 0x7fb3d280d400] \u001b[0mkb/s:1440.64\n"
     ]
    }
   ],
   "metadata": {}
  }
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ffmpeg can be installed on osx with homebrew.

output video:

animated-chart.mp4

ffmpeg params from https://hamelot.io/visualization/using-ffmpeg-to-convert-a-set-of-images-into-a-video/ 😹