问题
I'm trying to find an easier way for the following purpose of data manipulation. The dataframe is like this:
"object" "Date_In" "Date_out" "label" "room" "test"
"1" "LEU_A" 6 9 "Up" "11z" "c"
"2" "LEU_A" 1 10 "Down" "14x" "c"
"3" "LEU_B" 6 8 "Up" "11z" "a1"
"4" "LEU_B" 10 13 "Down" "14x" "a1"
"5" "ALL_A" 7 8 "Up" "11z" "c"
"6" "ALL_A" 1 26 "Down" "1g" "c"
"7" "CLMIA_A" 5 15 "Up" "11z" "a2"
"8" "CLMIA_A" 10 10 "Down" "14x" "a2"
"9" "CLMIA_A" 10 12 "Down" "13w" "a2"
For all rows with "Up" label (in the "label" col), I will combine it with each of the rows, which has same object name, but with "Down" label. The resulting new row (preferably in a new table) should have a column containing both "Date In" from the up-labeled row, and "Room" from the down-labeled row. A sample result dataframe can look like:
"object" "Date_In_Room"
"1" "LEU_A" "6_14x"
"2" "LEU_B" "6_14x"
"3" "ALL_A" "7_1g"
"4" "CLMIA_A" "5_14x"
"5" "CLMIA_A" "5_13w"
Note that it is possible for one sample labeled with "up" to have more than one related "down" labeled rows, and I'd like to include all of them. I could do it by first separate up and down rows, and then looping row by row within the dataframe, but that can be time-consuming, especially when I have hundreds of objects. Please let me know if you have some easier methods:)
Thanks a lot for reading. I appreciate your help.
Helene
回答1:
library(data.table)
DT <- as.data.table(your_data_frame)
RESULTS <- DT[, list(Date_In[label=="Up"], room[label=="Down"]), keyby=object]
RESULTS
object V1 V2
1: ALL_A 7 1g
2: CLMIA_A 5 14x
3: CLMIA_A 5 13w
4: LEU_A 6 14x
5: LEU_B 6 14x
来源：https://stackoverflow.com/questions/26224654/r-combine-columns-based-on-different-information-in-another-column-of-a-datafra