如何在R的小型数据框中的新变量中添加因子？

Question

Quick question: I have a small dataset that I melted and now would like to add a column variable:

> df
          taxa  spring summer     fall LocationA LocationB
1 Chironominae 1957.50 537.54 3396.765  1712.196   2958.642
2   Culicoides  863.53 343.08 2796.647  1907.804   1384.642
3     Naididae  949.88  40.75  147.569   641.911     91.566
4     Asioplax 1799.41 163.04  119.882     0.000   1343.528
5     Nematoda    0.00 166.00   27.647    53.679     45.057
6  Stilobezzia    0.00  20.38  885.961   605.179    222.321

taxa <- melt(df)

> taxa
           taxa   variable    value
1  Chironominae     spring 1957.500
2    Culicoides     spring  863.530
3      Naididae     spring  949.880 .....

How do I add a column for "variable.type" that defines whether the "variable" is a season (rows 1:18) or a location (rows 19:30)? I tried:

taxa$variable.type <- c("Season"[1:18], "Location"[19:30])

but just ended up with a column with lots of NAs.

thanks!

Answer 1

尝试：

df$variable.type <- ifelse(df$variable %in% c("spring","summer","fall"),"season","location")