我想在 dataframe 中迭代，在另一个 dataframe 中添加值（新列）

Question

I have a dataframe with dates in one row: ej:

CULTIVAR/ START DATE / END DATE

x / 11.02.2020  / 11.02.2021

And Another Dataframe with a list of days and ambiental variables: ej:

 Date                Humidity

01.01.2020 /   80

02.01.2020 /   85

03.01.2020 /   90

I need a code to add the Ambiental Variables to the first dataframe acording to the match in the days. So if i need the mean Humidity from the start date to the end date for the cultivar X, it goes to the second dataframe and iterates over the dates, maches them and add the mean humidity in the first dataframe.

Answer 1

An approach with R that adds mean_humidity to the first data frame by checking if the dates from df2 fall within the given start and end date from df1

Example data

df1
  cul      start        end
1   x 2020-02-11 2020-03-22
2   y 2020-03-11 2020-03-12
3   z 2020-04-11 2020-04-11
4   o 2020-05-11 2020-05-11

df2
        date humidity
1 2020-02-11       34
2 2020-03-11       45
3 2020-03-12       26
4 2020-03-13       65
5 2020-04-11       67
6 2020-05-15       78

Use

df1$mean_humidity <- rowMeans(
  sapply(seq_along(df2$date), function(x) 
    ifelse(df2$date[x] >= df1$start & 
           df2$date[x] <= df1$end, 
           df2$humidity[x], NA)
  ), na.rm=T)

df1
  cul      start        end mean_humidity
1   x 2020-02-11 2020-03-22          42.5
2   y 2020-03-11 2020-03-12          35.5
3   z 2020-04-11 2020-04-11          67.0
4   o 2020-05-11 2020-05-11           NaN

dput() data

df1 <- structure(list(cul = c("x", "y", "z", "o"), start = structure(c(18303, 
18332, 18363, 18393), class = "Date"), end = structure(c(18343, 
18333, 18363, 18393), class = "Date")), class = "data.frame", row.names = c(NA, 
-4L))

df2 <- structure(list(date = structure(c(18303, 18332, 18333, 18334, 
18363, 18397), class = "Date"), humidity = c(34, 45, 26, 65, 
67, 78)), row.names = c(NA, -6L), class = "data.frame")