我有一个网格数据作为数据框架，每天的温度（K）为30年。我需要提取与另一个数据框匹配的天数，并保留第一列和第二列（lon和lat）。
数据示例：
网格化数据，我需要从中删除与第二个数据中的天数不匹配的天数（df2 $ Dates）
>head(Daily.df)
lon lat 1991-05-01 1991-05-02 1991-05-03 1991-05-04 1991-05-05 1991-05-06 1991-05-07 1991-05-08 1991-05-09
1 5.000 60 278.2488 280.1225 280.3909 279.4138 276.6809 276.2085 276.6250 277.7930 276.9693
2 5.125 60 278.2514 280.1049 280.3789 279.4395 276.7141 276.2467 276.6571 277.8264 277.0225
3 5.250 60 278.2529 280.0871 280.3648 279.4634 276.7437 276.2849 276.6918 277.8608 277.0740
4 5.375 60 278.2537 280.0687 280.3488 279.4858 276.7691 276.3238 276.7289 277.8960 277.1232
5 5.500 60 278.2537 280.0493 280.3319 279.5066 276.7909 276.3633 276.7688 277.9313 277.1701
6 5.625 60 278.2539 280.0294 280.3143 279.5264 276.8090 276.4042 276.8111 277.9666 277.2147
1991-05-10 1991-05-11 1991-05-12 1991-05-13 1991-05-14 1991-05-15 1991-05-16 1991-05-17 1991-05-18 1991-05-19
1 276.9616 277.3436 273.3149 274.4931 274.6967 275.6298 272.2511 271.5413 271.7289 271.7964
2 276.9689 277.2988 273.3689 274.5399 274.6801 275.6307 272.2214 271.4445 271.6410 271.7023
3 276.9720 277.2533 273.4225 274.5811 274.6646 275.6241 272.1858 271.3391 271.5424 271.5989
4 276.9716 277.2080 273.4726 274.6146 274.6507 275.6109 272.1456 271.2274 271.4340 271.4872
5 276.9689 277.1632 273.5163 274.6382 274.6380 275.5917 272.1022 271.1121 271.3168 271.3693
6 276.9645 277.1190 273.5507 274.6501 274.6263 275.5672 272.0571 270.9955 271.1919 271.2469
1991-05-20 1991-05-21 1991-05-22 1991-05-23 1991-05-24 1991-05-25 1991-05-26 1991-05-27 1991-05-28 1991-05-29
1 272.2633 268.0039 268.5981 269.4139 267.7836 265.8771 263.5669 266.1666 269.7285 272.5083
2 272.2543 268.0218 268.5847 269.4107 267.7886 265.8743 263.5125 266.1031 269.6471 272.4676
3 272.2434 268.0369 268.5716 269.4089 267.7910 265.8669 263.4592 266.0332 269.5697 272.4217
4 272.2308 268.0507 268.5597 269.4090 267.7925 265.8559 263.4066 265.9581 269.4987 272.3714
5 272.2164 268.0642 268.5505 269.4112 267.7936 265.8425 263.3546 265.8797 269.4355 272.3175
6 272.2005 268.0793 268.5451 269.4154 267.7962 265.8276 263.3039 265.7997 269.3818 272.2614
1991-05-30 1991-05-31 1991-06-01 1991-06-02 1991-06-03 1991-06-04 1991-06-05 1991-06-06 1991-06-07 1991-06-08
1 274.2950 273.4715 274.5197 274.7548 273.8259 272.4433 274.1811 274.4135 274.3999 276.0327
2 274.2205 273.4638 274.5292 274.8316 273.8658 272.4700 274.1992 274.4426 274.4650 276.0698
3 274.1421 273.4549 274.5373 274.9027 273.9028 272.4980 274.2160 274.4781 274.5309 276.1012
4 274.0609 273.4452 274.5438 274.9665 273.9365 272.5273 274.2322 274.5211 274.5969 276.1255
5 273.9784 273.4353 274.5482 275.0216 273.9660 272.5576 274.2481 274.5725 274.6617 276.1417
6 273.8960 273.4253 274.5508 275.0668 273.9912 272.5887 274.2649 274.6334 274.7239 276.1487
1991-06-09 1991-06-10 1991-06-11 1991-06-12 1991-06-13 1991-06-14 1991-06-15 1991-06-16 1991-06-17 1991-06-18
1 276.5216 277.1812 277.8093 278.3013 278.5323 278.5403 277.9563 278.3461 275.8296 273.8277
2 276.5531 277.1925 277.8261 278.3409 278.4956 278.5317 277.9148 278.3234 275.8167 273.8302
3 276.5861 277.2065 277.8457 278.3748 278.4503 278.5181 277.8654 278.2939 275.8057 273.8358
4 276.6204 277.2239 277.8684 278.4029 278.3988 278.4996 277.8080 278.2583 275.7966 273.8427
5 276.6564 277.2466 277.8945 278.4253 278.3423 278.4759 277.7429 278.2171 275.7888 273.8504
6 276.6938 277.2753 277.9242 278.4414 278.2834 278.4472 277.6715 278.1714 275.7819 273.8570
1991-06-19 1991-06-20 1991-06-21 1991-06-22 1991-06-23 1991-06-24 1991-06-25 1991-06-26 1991-06-27 1991-06-28
1 275.1738 274.6805 275.6100 274.8936 273.5818 273.2099 273.1788 271.2747 273.2458 276.9931
2 275.1808 274.7123 275.7043 274.9494 273.5861 273.1770 273.2280 271.2435 273.2662 276.9822
3 275.1859 274.7478 275.7993 275.0009 273.5956 273.1439 273.2730 271.2133 273.2803 276.9678
4 275.1891 274.7879 275.8941 275.0467 273.6107 273.1106 273.3130 271.1840 273.2886 276.9502
5 275.1902 274.8337 275.9870 275.0857 273.6318 273.0777 273.3472 271.1556 273.2918 276.9307
6 275.1891 274.8864 276.0776 275.1168 273.6589 273.0454 273.3752 271.1285 273.2905 276.9101
1991-06-29 1991-06-30
1 272.0784 273.5677
2 272.0577 273.5973
3 272.0339 273.6237
4 272.0075 273.6476
5 271.9794 273.6701
6 271.9500 273.6925
我用于提取的第二个数据（使用Dates变量）
>head(df2)
Dates Temp Wind.S Wind.D
1 5/1/1991 18 4 238
2 5/2/1991 18 8 93
3 5/4/1991 22 8 229
4 5/6/1991 21 4 81
5 5/7/1991 21 8 192
6 5/9/1991 17 8 32
7 5/13/1991 22 8 229
8 5/18/1991 21 4 81
9 6/2/1991 21 8 192
10 6/7/1991 17 8 32
我正在寻找的最终数据的标题是这样的：
>head(df3)
lon lat 1991-05-01 1991-05-02 1991-05-04 1991-05-06 1991-05-09 1991-05-13
答案 0 :(得分：0)
遵循您的格式的示例数据
Daily.df <- data.frame(lon=1:5,lat=1:5,A=1:5,B=1:5,C=1:5,D=1:5)
colnames(Daily.df) <- c("lon","lat","1991-05-01","1991-05-02","1991-05-03","1991-05-04")
lon lat 1991-05-01 1991-05-02 1991-05-03 1991-05-04
1 1 1 1 1 1 1
2 2 2 2 2 2 2
3 3 3 3 3 3 3
4 4 4 4 4 4 4
5 5 5 5 5 5 5
df2 <- data.frame(Dates = c("5/1/1991","5/2/1991","5/4/1991"))
Dates
1 5/1/1991
2 5/2/1991
3 5/4/1991
使用lubridate将df2$Dates转换为正确的格式，制作要保留的列名称的向量（thesedates），包括lon和{{1} }。然后使用lat保留这些列。
select_at输出
library(lubridate)
library(dplyr)
thesedates <- c("lon","lat",as.character(mdy(df2$Dates)))
new.df <- Daily.df %>%
select_at(vars(thesedates))
答案 1 :(得分：0)
如果你想要一个长数据集来匹配，我认为你需要先将df2中的日期转换为正确的格式，然后将数据格式化为宽格式。
第1步 - 将日期转换为正确的格式
df2$Dates <- as.Date(df2$Dates, format = "%m/%d/%Y")
第2步 - 转换为宽幅
library(tidyr)
spread(df2, Dates, data)