我有一个数据集 df，格式为：
Country Population
US 1000
Germany 3000
Brazil 5000
France 6000
......
我想将人口视为密度，并在世界地图中以渐变颜色绘制密度。
我的代码如下：
df <- joinCountryData2Map(df, joinCode="NAME", nameJoinColumn="country")
tm_shape(World)+
tm_shape(df)+
tm_polygons(df$Population, palette = "-Blues",
title = "Income class", contrast = 0.7,
border.col = "gray30", id = "name") +
tm_fill(df$Population)+
tm_text("iso_a3", size = "AREA", col = "gray30", root=3) +
tm_style_classic()
错误：在每个 tm_shape 之后至少指定一层
我有两个问题：
1）如何按描述绘制国家数据？
2）如何将原始数据集df转换为Spatial、Raster或sf数据？除了我使用的“countrycode”包之外，如何以更清晰的方式转换数据，如 sp/sf/rgal 或 raster，以便我可以看到和理解空间数据转换的过程？
任何帮助，将不胜感激。
用 dput 更新，我找到了这个公共数据集包“wpp2015”，并生成了一个简单的数据集很好地代表了我的问题：
dput(df) <- structure(list(name = structure(c(1L, 3L, 4L, 5L, 6L, 14L, 7L, 11L, 13L, 15L, 16L, 17L, 8L, 18L, 20L, 23L, 24L, 25L, 26L, 27L, 21L, 190L, 28L, 29L, 146L, 31L, 19L, 33L, 34L, 35L, 32L, 37L, 201L, 40L, 42L, 43L, 46L, 47L, 48L, 134L, 49L, 58L, 50L, 52L, 53L, 55L, 56L, 22L, 59L, 61L, 65L, 67L, 68L, 71L, 69L, 70L, 73L, 74L, 75L, 76L, 77L, 60L, 78L, 80L, 79L, 203L, 81L, 82L, 108L, 83L, 84L, 85L, 86L, 87L, 88L, 90L, 91L, 93L, 44L, 94L, 95L, 96L, 97L, 98L, 99L, 100L, 101L, 102L, 51L, 103L, 104L, 106L, 105L, 107L, 57L, 173L, 109L, 110L, 111L, 115L, 116L, 113L, 119L, 120L, 121L, 124L, 45L, 125L, 126L, 127L, 128L, 129L, 130L, 131L, 132L, 133L, 136L, 141L, 174L, 142L, 144L, 145L, 160L, 147L, 148L, 149L, 54L, 9L, 150L, 231L, 151L, 152L, 153L, 154L, 158L, 138L, 162L, 163L, 164L, 165L, 166L, 167L, 168L, 170L, 89L, 214L, 171L, 172L, 175L, 176L, 177L, 178L, 179L, 202L, 181L, 182L, 183L, 184L, 185L, 186L, 187L, 188L, 233L, 189L, 191L, 194L, 241L, 200L, 196L, 205L, 237L, 206L, 207L, 208L, 209L, 210L, 211L, 213L, 215L, 216L, 217L, 223L, 218L, 219L, 220L, 221L, 222L, 212L, 66L, 224L, 41L, 225L, 226L, 227L, 30L, 229L, 230L, 232L, 180L, 239L, 240L, 238L, 143L, 117L, 2L, 112L, 156L, 63L, 72L, 159L, 62L, 140L, 155L, 197L, 234L, 36L, 38L, 193L, 192L, 235L, 64L, 157L, 199L, 236L, 12L, 135L, 195L, 161L, 10L, 114L, 204L, 118L, 137L, 169L, 122L, 123L, 228L, 92L, 139L, 39L, 198L), .Label = c("Afghanistan", "Africa", "Albania", "Algeria", "Angola", "Antigua and Barbuda", "Argentina", "Armenia", "Aruba", "Asia", "Australia", "Australia/New Zealand", "Austria", "Azerbaijan", "Bahamas", "Bahrain", "Bangladesh", "Barbados", "Belarus", "Belgium", "Belize", "Benin", "Bhutan", "Bolivia (Plurinational State of)", "Bosnia and Herzegovina", "Botswana", "Brazil", "Brunei Darussalam", "Bulgaria", "Burkina Faso", "Burundi", "Cabo Verde", "Cambodia", "Cameroon", "Canada", "Caribbean", "Central African Republic", "Central America", "Central Asia", "Chad", "Channel Islands", "Chile", "China", "China, Hong Kong SAR", "China, Macao SAR", "China, Taiwan Province of China", "Colombia", "Comoros", "Congo", "Costa Rica", "Cote d'Ivoire", "Croatia", "Cuba", "Curacao", "Cyprus", "Czech Republic", "Dem. People's Rep. of Korea", "Dem. Republic of the Congo", "Denmark", "Djibouti", "Dominican Republic", "Eastern Africa", "Eastern Asia", "Eastern Europe", "Ecuador", "Egypt", "El Salvador", "Equatorial Guinea", "Eritrea", "Estonia", "Ethiopia", "Europe", "Fiji", "Finland", "France", "French Guiana", "French Polynesia", "Gabon", "Gambia", "Georgia", "Germany", "Ghana", "Greece", "Grenada", "Guadeloupe", "Guam", "Guatemala", "Guinea", "Guinea-Bissau", "Guyana", "Haiti", "High-income countries", "Honduras", "Hungary", "Iceland", "India", "Indonesia", "Iran (Islamic Republic of)", "Iraq", "Ireland", "Israel", "Italy", "Jamaica", "Japan", "Jordan", "Kazakhstan", "Kenya", "Kiribati", "Kuwait", "Kyrgyzstan", "Lao People's Dem. Republic", "Latin America and the Caribbean", "Latvia", "Least developed countries", "Lebanon", "Lesotho", "Less developed regions", "Less developed regions, excluding China", "Liberia", "Libya", "Lithuania", "Low-income countries", "Lower-middle-income countries", "Luxembourg", "Madagascar", "Malawi", "Malaysia", "Maldives", "Mali", "Malta", "Martinique", "Mauritania", "Mauritius", "Mayotte", "Melanesia", "Mexico", "Micronesia", "Micronesia (Fed. States of)", "Middle-income countries", "Middle Africa", "Mongolia", "Montenegro", "More developed regions", "Morocco", "Mozambique", "Myanmar", "Namibia", "Nepal", "Netherlands", "New Caledonia", "New Zealand", "Nicaragua", "Niger", "Nigeria", "Northern Africa", "Northern America", "Northern Europe", "Norway", "Oceania", "Oman", "Other less developed countries", "Pakistan", "Panama", "Papua New Guinea", "Paraguay", "Peru", "Philippines", "Poland", "Polynesia", "Portugal", "Puerto Rico", "Qatar", "Republic of Korea", "Republic of Moldova", "Reunion", "Romania", "Russian Federation", "Rwanda", "Saint Lucia", "Samoa", "Sao Tome and Principe", "Saudi Arabia", "Senegal", "Serbia", "Seychelles", "Sierra Leone", "Singapore", "Slovakia", "Slovenia", "Solomon Islands", "Somalia", "South-Central Asia", "South-Eastern Asia", "South Africa", "South America", "South Sudan", "Southern Africa", "Southern Asia", "Southern Europe", "Spain", "Sri Lanka", "St. Vincent and the Grenadines", "State of Palestine", "Sub-Saharan Africa", "Sudan", "Suriname", "Swaziland", "Sweden", "Switzerland", "Syrian Arab Republic", "Tajikistan", "TFYR Macedonia", "Thailand", "Timor-Leste", "Togo", "Tonga", "Trinidad and Tobago", "Tunisia", "Turkey", "Turkmenistan", "Uganda", "Ukraine", "United Arab Emirates", "United Kingdom", "United Republic of Tanzania", "United States of America", "United States Virgin Islands", "Upper-middle-income countries", "Uruguay", "Uzbekistan", "Vanuatu", "Venezuela (Bolivarian Republic of)", "Viet Nam", "Western Africa", "Western Asia", "Western Europe", "Western Sahara", "World", "Yemen", "Zambia", "Zimbabwe"), class = "factor"), `1950` = c(7752.118, 1263.171, 8872.247, 4354.882, 46.301, 2895.997, 17150.335, 8177.344, 6936.445, 79.088, 115.614, 37894.68, 1353.506, 210.995, 8628.489, 176.795, 3089.649, 2661.293, 412.533, 53974.726, 68.918, 89.793, 48.001, 7250.999, 17527.243, 2308.923, 7745.003, 4432.716, 4466.498, 13736.997, 178.066, 1326.653, 8075.81, 2502.314, 6142.899, 544112.923, 7561.863, 12340.899, 156.334, 15.141, 807.726, 12183.661, 959.489, 3850.295, 5919.997, 494.014, 8902.619, 2255.221, 4268.27, 2364.65, 3470.162, 2199.897, 225.536, 18128.034, 1142.15, 1100.998, 288.993, 4008.299, 41879.607, 25.479, 60.268, 62.001, 473.3, 3527.004, 271.372, 931.926, 69786.246, 4980.878, 33.05, 7566.002, 76.676, 209.999, 59.65, 3146.073, 3093.651, 406.562, 3221.277, 1487.235, 1973.998, 9337.723, 142.656, 376325.205, 69543.319, 17119.263, 5719.191, 2913.093, 1257.971, 46598.602, 2630.131, 1402.896, 82199.47, 6702.996, 448.861, 6076.757, 10549.469, 19211.386, 152.25, 1740, 1682.916, 1334.618, 733.942, 1949, 930.026, 1113.382, 2567.402, 296.001, 196.482, 4083.554, 2953.871, 6109.907, 73.715, 4708.425, 311.997, 222.001, 660.491, 493.254, 28012.558, 780.2, 2341.003, 394.738, 8985.99, 6313.29, 456.418, 485.274, 8483.321, 10027.047, 100.184, 38.066, 64.824, 47.695, 1908.001, 1294.993, 2559.703, 37859.745, 3265.278, 32, 37542.38, 859.66, 1708.192, 1473.245, 7727.735, 18580.487, 24824.013, 8416.969, 535.429, 433.398, 2218, 24.999, 248.111, 16236.292, 102798.657, 2186.187, 82.783, 67, 60, 3121.336, 2476.638, 6732.256, 36.322, 1944.001, 1022.098, 3436.574, 24809.903, 1473.094, 2264.081, 13683.162, 2746.854, 28069.737, 2582.929, 5733.944, 13.766, 214.999, 273, 7009.913, 4668.088, 3413.329, 1531.502, 20710.356, 1395.458, 47.22, 645.628, 69.59, 3605.31, 21238.496, 1211, 5158.193, 37297.652, 1254.444, 20897.237, 50616.012, 102.235, 7649.766, 157813.04, 26.795, 4284.457, 2238.506, 6945.397, 5481.977, 82.102, 4402.32, 2316.95, 2525149.312, 812988.79, 1712160.522, 228901.723, 168843.911, 171614.868, 666585.791, 549089.107, 12681.946, 66922.702, 26400.57, 49221.876, 15587.911, 70768.664, 17075.654, 38028.823, 164900.344, 511574.182, 50957.44, 220170.535, 78029.913, 108632.979, 142255.68, 10085.345, 2199.497, 113739.434, 1516435.967, 1394017.757, 195724.555, 179679.847, 1158315.256, 155.093, 242.011, 130103.438, 768893.01, 824937.314, 800383.367, 1593830.324, 18130.895, 493443.287)), .Names = c("name", "1950"), class = "data.frame", row.names = c(NA, -241L))
