R - 数据帧中的条件更新坐标列

Question

我试图在数据框中填充两个新空列，其中包含来自同一数据框中其他列的数据，具体取决于它们是否已填充。

我正在尝试填充HIGH_PRCN_LAT和HIGH_PRCN_LON（以前称为F_Lat和F_Lon）的值，这些值表示这些行的最终纬度和行程，这将基于表中其他列的值。

情况1：填充Lat / Lon2（如ID 1和2中），使用大圆算法，应计算它们之间的中点，然后放入F_Lat和F_Lon。

情况2：Lat / Lon2为空，然后Lat / Lon1的值应放入F_Lat和F_Lon（与ID 3和4一样）。

我的代码如下，但不起作用（请参阅以前的版本，在编辑中删除）。

我使用的准备代码如下：

incidents <- structure(list(id = 1:9, StartDate = structure(c(1L, 3L, 2L, 
2L, 2L, 3L, 1L, 3L, 1L), .Label = c("02/02/2000 00:34", "02/09/2000 22:13", 
"20/01/2000 14:11"), class = "factor"), EndDate = structure(1:9, .Label = c("02/04/2006 20:46", 
"02/04/2006 22:38", "02/04/2006 23:21", "02/04/2006 23:59", "03/04/2006 20:12", 
"03/04/2006 23:56", "04/04/2006 00:31", "07/04/2006 06:19", "07/04/2006 07:45"
), class = "factor"), Yr.Period = structure(c(1L, 1L, 2L, 2L, 
2L, 3L, 3L, 3L, 3L), .Label = c("2000 / 1", "2000 / 2", "2000 /3"
), class = "factor"), Description = structure(c(1L, 1L, 1L, 1L, 
1L, 1L, 1L, 1L, 1L), .Label = "ENGLISH TEXT", class = "factor"), 
    Location = structure(c(2L, 2L, 1L, 2L, 2L, 2L, 2L, 1L, 1L
    ), .Label = c("Location 1", "Location 1 : Location 2"), class = "factor"), 
    Location.1 = structure(c(1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 
    1L), .Label = "Location 1", class = "factor"), Postcode.1 = structure(c(1L, 
    1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L), .Label = "Postcode 1", class = "factor"), 
    Location.2 = structure(c(2L, 2L, 1L, 2L, 2L, 2L, 2L, 1L, 
    1L), .Label = c("", "Location 2"), class = "factor"), Postcode.2 = structure(c(2L, 
    2L, 1L, 2L, 2L, 2L, 2L, 1L, 1L), .Label = c("", "Postcode 2"
    ), class = "factor"), Section = structure(c(2L, 2L, 3L, 1L, 
    4L, 4L, 2L, 1L, 4L), .Label = c("East", "North", "South", 
    "West"), class = "factor"), Weather.Category = structure(c(1L, 
    2L, 4L, 2L, 2L, 2L, 4L, 1L, 3L), .Label = c("Animals", "Food", 
    "Humans", "Weather"), class = "factor"), Minutes = c(13L, 
    55L, 5L, 5L, 5L, 522L, 1L, 11L, 22L), Cost = c(150L, 150L, 
    150L, 20L, 23L, 32L, 21L, 11L, 23L), Location.1.Lat = c(53.0506727, 
    53.8721035, 51.0233529, 53.8721035, 53.6988355, 53.4768766, 
    52.6874562, 51.6638245, 51.4301359), Location.1.Lon = c(-2.9991256, 
    -2.4004125, -3.0988341, -2.4004125, -1.3031529, -2.2298073, 
    -1.8023421, -0.3964916, 0.0213837), Location.2.Lat = c(52.7116187, 
    53.746791, NA, 53.746791, 53.6787167, 53.4527824, 52.5264907, 
    NA, NA), Location.2.Lon = c(-2.7493169, -2.4777984, NA, -2.4777984, 
    -1.489026, -2.1247029, -1.4645023, NA, NA)), class = "data.frame", row.names = c(NA, -9L))

#gpsColumns is used as the following line of code is used for several data frames.
gpsColumns <- c("HIGH_PRCN_LAT", "HIGH_PRCN_LON")
incidents [ , gpsColumns] <- NA

#create separate variable(?) containing a list of which rows are complete
ind <- complete.cases(incidents [,17])

#populate rows with a two Lat/Lons with great circle middle of both values
incidents [ind, c("HIGH_PRCN_LON_2","HIGH_PRCN_LAT_2")] <- 
  with(incidents [ind,,drop=FALSE],
       do.call(rbind, geosphere::midPoint(cbind.data.frame(Location.1.Lon, Location.1.Lat), cbind.data.frame(Location.2.Lon, Location.2.Lat))))

#populate rows with one Lat/Lon with those values
incidents[!ind, c("HIGH_PRCN_LAT","HIGH_PRCN_LON")] <- incidents[!ind, c("Location.1.Lat","Location.1.Lon")]

我将根据推荐使用geosphere :: midPoint函数：http://r.789695.n4.nabble.com/Midpoint-between-coordinates-td2299999.html。

不幸的是，当有几种情况时，这种填充列的方式似乎不起作用。

抛出的当前错误是：

Error in `$<-.data.frame`(`*tmp*`, F_Lat, value = integer(0)) : 
  replacement has 0 rows, data has 178012

编辑：也发布到reddit：https://www.reddit.com/r/Rlanguage/comments/bdvavx/conditional_updating_column_in_dataframe/

编辑：添加了我不理解的代码部分的清晰度。

#replaces the F_Lat2/F_Lon2 columns in rows with a both sets of input coordinates 
dataframe[ind, c("F_Lat2","F_Lon2")] <-
#I am unclear on what this means, specifically what the "with" function does and what "drop=FALSE" does and also why they were used in this case.
  with(dataframe[ind,,drop=FALSE],
#I am unclear on what do.call and rbind are doing here, but the second half (geosphere onwards) is binding the Lats and Lons to make coordinates as inputs for the gcIntermediate function.
       do.call(rbind, geosphere::gcIntermediate(cbind.data.frame(Lat1, Lon1),
                                                cbind.data.frame(Lat2, Lon2), n = 1)))