Motivation for the course
=========================
The main part of the first half of this course is to learn to program in Python.
However, in addition to learning to program, we hope to help you learn a number of other skills related to open science.
These include:
1. Writing programs that are easy to understand and share
2. Keeping a log of the changes you make to your programs
3. Using programs that ensure your science is reproducible
4. Producing simple, effective data visualizations that make your results easy to understand
To help clarify our goals, consider the example below.
Effective data visualization
----------------------------
One of the things we will learn in this course is how to use Python to plot data.
As you well know, raw data itself is often not particularly useful in helping you understand what the data shows.
Let's look at an example that might be familiar to you, global temperature anomalies.
And we can start with the data.
.. code-block:: none
-9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -84 -42 -27 -10 6 -5 8 55 163 330 525 731 957 1191 1429 1669 1883 2044 2155 2227 2262 2266 2250 2232 2228 2247 2289 2355 2440 2535 2626 2693 2726 2748 2789 2819 2808 2791 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 1351 1312 -9999 -9999 -9999 -9999 -9999 852 -9999 736 764 777 743 643 528 439 312 138 19 3 -15 -180 -180 -180 -180 -180
-9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -123 -82 -39 -25 -12 -13 -12 -5 47 156 323 518 726 952 1188 1430 1673 1885 2039 2139 2199 2224 2225 2214 2205 2212 2241 2293 2368 2464 2571 2668 2734 2761 2777 2811 2834 2822 2803 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 1376 1333 -9999 -9999 -9999 -9999 -9999 745 712 700 722 741 734 672 569 472 342 184 65 50 42 -180 -180 -180 -180 -180
-9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -131 -83 -38 -25 -16 -23 -20 -12 41 148 310 500 707 936 1179 1429 1677 1886 2033 2122 2169 2184 2182 2175 2177 2193 2231 2293 2382 2494 2611 2710 2776 2798 2806 2829 2850 2841 2830 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 1423 1368 1297 1262 -9999 -9999 -9999 693 669 667 680 699 699 660 592 498 374 241 132 116 106 -180 -180 -180 -180 -180
-9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -132 -85 -39 -25 -18 -34 -30 -19 34 146 299 483 685 914 1167 1430 1682 1887 2025 2102 2136 2143 2139 2139 2148 2166 2208 2283 2394 2528 2655 2752 2813 2830 2828 2847 2856 2851 2841 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 1462 1406 1332 1294 -9999 -9999 -9999 -9999 604 617 635 662 670 645 602 523 414 306 208 174 150 -91 -180 -180 -180 -180
-9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -137 -92 -43 -25 -19 -42 -38 -31 24 141 291 473 674 902 1162 1438 1695 1894 2018 2081 2105 2108 2104 2104 2108 2115 2154 2252 2402 2564 2696 2785 2833 2843 2844 2848 2853 2849 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 1485 1439 1373 1332 -9999 -9999 -9999 -9999 450 489 525 -9999 -9999 621 602 544 455 348 237 173 150 -19 -180 -180 -180 -180
-9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -148 -102 -47 -25 -19 -50 -51 -42 12 123 275 470 681 915 1183 1468 1726 1914 2021 2067 2081 2075 2058 2043 2032 2027 2074 2212 2412 2597 2721 2794 2826 2828 2837 2844 2850 2848 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 1516 1467 1417 1373 -9999 -9999 -9999 -9999 295 319 387 -9999 -9999 599 590 554 480 376 228 152 125 -51 -180 -180 -180 -180
-9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -163 -112 -51 -26 -20 -58 -58 -45 0 98 262 469 696 949 1238 1536 1787 1953 2035 2061 2055 2019 1964 1923 1905 1914 2000 2187 2435 2626 2721 2780 2803 2822 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 1691 1631 1554 1502 1450 -9999 -9999 -9999 -9999 -9999 -9999 245 303 -9999 -9999 -9999 557 538 483 408 261 168 113 -92 -180 -180 -180 -180
-9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -175 -117 -51 -26 -19 -62 -59 -45 0 86 253 468 710 994 1322 1638 1872 2001 2044 2036 1998 1939 1861 1801 1791 1828 -9999 -9999 -9999 2650 2704 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 1726 1659 1581 1531 1457 1369 1315 -9999 -9999 -9999 -9999 248 -9999 -9999 -9999 -9999 -9999 481 475 422 300 189 110 -109 -180 -180 -180 -180
-9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -168 -113 -50 -25 -12 -57 -55 -35 0 83 245 461 717 1035 1406 1743 1955 2034 2025 1973 1916 1882 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 1798 1753 1677 1597 1537 -9999 1401 -9999 -9999 -9999 -9999 -9999 267 -9999 -9999 -9999 -9999 -9999 -9999 473 427 291 146 51 -129 -180 -180 -180 -180
-9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -98 -49 -26 -1 -52 -52 -35 -8 73 230 446 713 1064 1472 1827 2023 2061 2012 1927 1870 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 1808 1755 1682 1611 1549 1497 -9999 -9999 -9999 -9999 -9999 -9999 275 217 82 21 -9999 -9999 -9999 460 410 245 47 -180 -165 -180 -180 -180 -180
-9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -95 -51 -30 1 -49 -53 -47 -26 51 206 427 710 1083 1509 1873 2070 2102 2060 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 1801 1753 1692 1638 1572 1520 -9999 -9999 -9999 -9999 -9999 -9999 233 205 118 48 -4 -9999 -9999 -9999 401 199 -138 -179 -179 -180 -180 -180 -180
-9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -160 -111 -58 -36 8 -45 -52 -53 -41 32 187 413 709 1090 1512 1871 2083 2149 2141 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 1742 1693 1639 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 213 184 134 65 -18 -94 -9999 -9999 366 178 -144 -180 -180 -180 -180 -180 -180
-9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -180 -131 -68 -45 15 -27 -41 -47 -36 34 188 410 706 1078 1481 1825 2055 2172 2210 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 1752 1695 1619 1543 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 131 106 -9999 -9999 -117 -9999 -9999 364 200 -104 -180 -180 -180 -180 -180 -180
-9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -180 -147 -79 -48 14 -15 -25 -30 -11 58 204 421 710 1066 1450 1778 2015 2172 2256 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 1833 1782 1717 1636 1552 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 44 -9999 -9999 -9999 -9999 -9999 371 232 -53 -180 -180 -180 -180 -180 -180
-9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -153 -87 -50 5 -18 -11 -12 15 91 231 445 726 1063 1431 1754 1989 2160 2279 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 1846 1797 1747 1690 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 22 -9999 -9999 -9999 -9999 -9999 359 246 15 -180 -180 -180 -180 -180 -180
-9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -159 -92 -51 4 -22 -7 -4 33 116 257 470 740 1055 1409 1733 1969 2137 2279 2382 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 1856 1817 1785 -9999 -9999 890 834 780 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 310 326 241 39 -180 -180 -180 -180 -180 -180
-9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -168 -96 -49 10 -21 -7 0 44 133 272 478 733 1031 1380 1713 1952 2115 2259 2396 2490 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 1869 1837 1813 -9999 -9999 894 854 798 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 280 289 216 30 -180 -180 -180 -180 -180 -180
-9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -176 -97 -43 18 -17 -6 4 54 142 272 461 701 991 1348 1698 1944 2101 2240 2383 2506 2601 2657 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 2319 -9999 1877 1859 1845 -9999 -9999 -9999 853 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 249 246 174 6 -180 -180 -180 -180 -180 -180
-9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -180 -93 -35 25 -12 -4 9 60 142 258 432 657 947 1315 1680 1931 2088 2226 2370 2499 2595 2665 2724 2762 2775 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 2501 2406 2333 -9999 -9999 1862 1858 -9999 -9999 887 840 783 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -180 -9999 223 206 130 -20 -180 -180 -180 -180 -180 -180
-9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -180 -90 -30 29 -7 -6 6 57 134 246 412 628 914 1285 1651 1905 2063 2206 2354 2488 2586 2663 2732 2778 2797 2806 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 2718 2632 2542 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 912 864 796 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -180 -9999 196 172 96 -37 -180 -180 -180 -180 -180 -180
-9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -180 -96 -33 26 -2 -10 -6 42 124 242 407 613 888 1256 1623 1874 2031 2176 2333 2477 2582 2667 2748 2808 2835 2835 2834 -9999 -9999 -9999 2819 2797 2750 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 2707 2740 2740 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 959 921 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -174 -9999 166 153 83 -41 -180 -180 -180 -180 -180 -180
-9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -180 -101 -39 22 -1 -11 -18 26 120 248 410 599 862 1237 1613 1860 2007 2149 2311 2465 2583 2682 2774 2843 2870 2870 2861 2871 2885 2876 2831 2796 2726 2654 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 2681 2726 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 982 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 44 126 144 85 -35 -180 -180 -180 -180 -180 -180
-9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -96 -45 22 4 -5 -18 23 125 256 410 578 831 1217 1609 1855 1998 2139 2301 2458 2585 2687 2785 2864 2894 2894 2890 2894 2888 2879 2840 2796 2715 2631 2583 -9999 -9999 -9999 -9999 -9999 2568 2572 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 22 89 135 104 -15 -180 -180 -180 -180 -180 -180
-9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -97 -50 15 10 7 -4 39 142 268 402 553 800 1190 1591 1845 1997 2145 2304 2458 2585 2681 -9999 -9999 -9999 -9999 -9999 2906 2888 2879 2862 2806 2732 2648 2584 2558 -9999 -9999 -9999 -9999 2561 2564 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -92 60 131 125 -30 -180 -180 -180 -180 -180 -180
-9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -105 -54 11 14 19 15 69 172 285 399 540 785 1173 1570 1831 1997 2152 2310 2461 2588 2685 2753 -9999 -9999 -9999 -9999 2902 2879 2874 2856 2827 2765 2683 2598 2563 2558 -9999 -9999 -9999 2538 2545 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 448 373 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -180 35 117 129 -48 -180 -180 -180 -180 -180 -180
-9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -94 -54 5 15 27 34 99 204 307 407 546 801 1189 1574 1826 1992 2149 2310 2466 2597 2698 2779 2841 2878 2884 -9999 -9999 2865 2862 2851 2823 2771 2698 2626 2589 2584 2590 2596 -9999 2534 2526 -9999 -9999 -9999 -9999 -9999 -9999 1982 1942 -9999 -9999 -9999 1055 932 719 483 309 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -180 17 110 131 28 -180 -180 -180 -180 -180 -180
-9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -41 1 18 34 54 125 226 327 428 582 858 1248 1608 1834 1986 2140 2307 2471 2602 2706 2784 2841 2872 2883 2885 2884 2873 2853 2849 2819 2777 2716 2651 2613 2609 2611 2604 2580 2549 2525 2507 -9999 -9999 -9999 -9999 2121 2058 -9999 -9999 -9999 -9999 1103 989 811 520 25 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 13 57 109 -59 -180 -180 -180 -180 -180 -180
-9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -32 0 23 43 74 147 244 349 469 654 955 1336 1653 1846 1985 2136 2303 2463 2601 2705 2782 2833 2862 2877 2886 2887 2880 2853 2840 2811 2781 2735 2680 2648 2642 2642 2632 2608 2574 2532 2500 -9999 -9999 -9999 -9999 2192 -9999 -9999 -9999 -9999 -9999 1114 1033 909 -9999 259 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -120 24 -16 -144 -180 -180 -180 -180 -180 -180
-9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -31 2 30 55 93 169 264 376 524 752 1075 1425 1688 1851 1988 2138 2298 2456 2592 2697 2771 2819 2848 2867 2880 2887 2879 2854 2817 2795 2779 2751 2709 2684 2682 2681 2665 2634 2591 2541 2499 2477 -9999 -9999 -9999 2269 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -180 -180 -141 -155 -180 -180 -180 -180 -180 -180
-9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -63 -27 5 39 67 112 192 284 400 575 846 1184 1492 1701 1847 1992 2142 2298 2449 2582 2686 2755 2796 2824 2846 2862 2872 2872 2850 2818 2793 2779 2763 2737 2721 2718 2715 2697 2660 2609 2557 2512 2476 2447 -9999 -9999 2290 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -180 -180 -180 -175 -180 -180 -180 -180 -180 -180
-9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -62 -18 9 48 78 131 215 301 411 596 897 1245 1520 1698 1841 1994 2148 2300 2443 2570 2669 2734 2770 2797 2821 2840 2855 2862 2845 2814 2793 2779 2778 2762 2749 2745 2740 2719 2679 2627 2577 2532 2488 2447 2396 2348 2316 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -180 -180 -180 -180 -180 -180 -180 -180 -180 -180
...
Not that exciting, right?
There is an interesting story here, but we need some way to illustrate the power of this data.
One option is to use an *x*-*y* plot of temperature anomalies versus time.
.. figure:: https://www.ncdc.noaa.gov/sotc/service/global/global-land-ocean-mntp-anom/201101-201112.png
:width: 800px
:align: center
:alt: Global mean temperature anomalies
Global mean temperature anomalies from 1880-2011. Source: https://www.ncdc.noaa.gov/sotc/global/201113
This is obviously much better, showing clearly how temperatures have changed with time and how global temperatures have increased significantly since 1970.
Now we see a clear step toward making the data easier to understand.
However, this is global data and we are missing something important about the data, its connection to geographical locations.
Let's consider another option, plotting temperature anomalies on a map.
.. figure:: https://www.ncdc.noaa.gov/sotc/service/global/map-blended-mntp/201603.gif
:width: 800px
:align: center
:alt: Global mean temperature anomaly map
Global temperature anomalies for March 2016. Source: https://www.ncdc.noaa.gov/sotc/global/201603
And yet again, this helps us understand the data further.
Not only do we see the changed in temperature, but now we see how temperatures vary across the globe.
The drawback here is that we only see a single time snapshot, rather than a time series.
To see both will require a truly remarkable visualization.
So, let's look now at an excellent example of data visualization with Python.
We have essentially the same data plotted above, but now we can see how temperatures vary in space and time,
.. raw:: html
Global temperature anomalies by country from 1900-2016. Visualization by Antti Lipponen (@anttilip ). Source: https://flic.kr/p/W3wPeE
This animated radial plot of temperature anomalies conveys a huge amount of information in a simple form.
People can immediately understand what is plotted, and the combination of the plot format, colors and animation are very effective.
What even better is the fact that this animation was made using Python!
For the rest of the first part of this course, plots like that above can be our inspiration.
In fact, we will be working with similar data throughout this part of the course and may even end up producing similar plots in by the end of this teaching period.