使用R重塑数据框中的行组织

我有这个数据框。

structure(list(Driver = c("Crop agriculture", "Infrastructure", 
"Mining", "Mixed Agriculture", "Other land use", "Pasture", "Tree crops", 
"Water", "Crop agriculture", "Infrastructure", "Mining", "Mixed Agriculture", 
"Other land use", "Pasture", "Tree crops", "Water", "Crop agriculture", 
"Infrastructure", "Mining", "Mixed Agriculture", "Other land use", 
"Pasture", "Tree crops", "Water", "Crop agriculture", "Infrastructure", 
"Mining", "Mixed Agriculture", "Other land use", "Pasture", "Tree crops", 
"Water"), Period = c("1990-2000", "1990-2000", "1990-2000", "1990-2000", 
"1990-2000", "1990-2000", "1990-2000", "1990-2000", "1990-2000", 
"1990-2000", "1990-2000", "1990-2000", "1990-2000", "1990-2000", 
"1990-2000", "1990-2000", "2000-2005", "2000-2005", "2000-2005", 
"2000-2005", "2000-2005", "2000-2005", "2000-2005", "2000-2005", 
"2000-2005", "2000-2005", "2000-2005", "2000-2005", "2000-2005", 
"2000-2005", "2000-2005", "2000-2005"), Value = c(129536.358373574, 
14089.3660954917, 985.646531415156, 34951.5705930615, 75478.7796771996, 
1001024.77681633, 9673.51414314377, 51631.4446491193, 0.0983294102032751, 
0.0106950594852475, 0.000748191807457263, 0.0265312948831128, 
0.057294986378404, 0.759865238911138, 0.0073430421561273, 0.0391927761752383, 
273356.204972389, 12040.5899468613, 607.505228212054, 45165.8223684273, 
75748.9976185639, 1221137.74328547, 8851.85933777376, 39629.016246337, 
0.163048047540391, 0.00718181861746466, 0.000362357025480948, 
0.0269399377763239, 0.0451818028644936, 0.728368777437064, 0.00527984496372407, 
0.0236374137750571), n = c("n = 1669", "n = 298", "n = 20", "n = 1355", 
"n = 1623", "n = 10986", "n = 316", "n = 466", "n = 1669", "n = 298", 
"n = 20", "n = 1355", "n = 1623", "n = 10986", "n = 316", "n = 466", 
"n = 783", "n = 151", "n = 7", "n = 925", "n = 851", "n = 6039", 
"n = 211", "n = 244", "n = 783", "n = 151", "n = 7", "n = 925", 
"n = 851", "n = 6039", "n = 211", "n = 244"), Type = c("Sum", 
"Sum", "Sum", "Sum", "Sum", "Sum", "Sum", "Sum", "Percentage", 
"Percentage", "Percentage", "Percentage", "Percentage", "Percentage", 
"Percentage", "Percentage", "Sum", "Sum", "Sum", "Sum", "Sum", 
"Sum", "Sum", "Sum", "Percentage", "Percentage", "Percentage", 
"Percentage", "Percentage", "Percentage", "Percentage", "Percentage"
)), .Names = c("Driver", "Period", "Value", "n", "Type"), row.names = c("1", 
"3", "5", "7", "9", "11", "13", "15", "12", "31", "51", "71", 
"91", "111", "131", "151", "2", "4", "6", "8", "10", "122", "14", 
"16", "21", "41", "61", "81", "101", "121", "141", "161"), class = "data.frame")

我想根据两个条件重新组织此数据框。首先，我想在前8行中包含Sum对象，然后是百分比。然后，我也想将相同的驱动程序类耦合在一起。简而言之，例如，我想拥有Crop agriculture1990-2000年，紧随其后Crop agriculture的是2000-2005年，依此类推。谢谢你的帮助。