如何计算发生 10 米（0.01 公里）增长的行数？

Question

我有一个包含 3 列的 CSV：时间、经度、纬度。我需要每 10 米（0.01 公里）提取一次时间。我已经成功计算出每行的累积距离：

gps <- read.csv("SP1ST1.csv")
gps_sp <- SpatialPoints(cbind(gps$lng,gps$lat))
test <- spDistsN1(gps_sp, gps_sp[1,], longlat=TRUE)

所以输出看起来像这样：

 [1] 0.000000000 0.001586483 0.004574098 0.004493954 0.004887035 0.005405389 0.005930999 0.006443206 0.006991742 0.007595466 0.009693191
 [12] 0.010654023 0.010231435 0.010082614 0.012005496 0.012905777 0.013896484 0.014873557 0.015857558 0.016905208 0.013991941 0.017441699
 [23] 0.017797154 0.018539821 0.019254225 0.019914940 0.020634398 0.021411878 0.022246358 0.023037314 0.023832587 0.024608449 0.023977990

通过查看输出，我可以看到我的第一个大约 0.01 公里的增加是在第 1 行和第 11 行之间，第二个是在第 11 行和第 26 行之间。

我需要在 R 中编写一段代码，为我找到所有这些跳跃，但它不是精确的 0.01 跳跃，并且它不是均匀分布在行中。我还需要将其链接回原始的“gps”对象，以便我可以提取与 ~0.01 增加相关的时间。

我该怎么做？

编辑：在下面添加了数据示例。

sample <- dput(head(gps,30))

filename                         taken_at    lng     lat      gps_altitude
1  20230718_GSL_SP1ST1_4k_01.MOV  14:11:05 -65.36897 49.95216      -31.625
2  20230718_GSL_SP1ST1_4k_01.MOV  14:11:08 -65.36898 49.95218      -31.373
3  20230718_GSL_SP1ST1_4k_01.MOV  14:11:12 -65.36899 49.95220      -31.254
4  20230718_GSL_SP1ST1_4k_01.MOV  14:11:13 -65.36898 49.95220      -31.604
5  20230718_GSL_SP1ST1_4k_01.MOV  14:11:14 -65.36897 49.95221      -31.419
6  20230718_GSL_SP1ST1_4k_01.MOV  14:11:15 -65.36897 49.95221      -31.432
7  20230718_GSL_SP1ST1_4k_01.MOV  14:11:16 -65.36896 49.95222      -31.445
8  20230718_GSL_SP1ST1_4k_01.MOV  14:11:17 -65.36896 49.95222      -31.459
9  20230718_GSL_SP1ST1_4k_01.MOV  14:11:18 -65.36895 49.95222      -31.472
10 20230718_GSL_SP1ST1_4k_01.MOV  14:11:19 -65.36895 49.95223      -31.485
11 20230718_GSL_SP1ST1_4k_01.MOV  14:11:20 -65.36900 49.95225      -31.328
12 20230718_GSL_SP1ST1_4k_01.MOV  14:11:21 -65.36899 49.95226      -31.322
13 20230718_GSL_SP1ST1_4k_01.MOV  14:11:22 -65.36901 49.95225      -31.462
14 20230718_GSL_SP1ST1_4k_01.MOV  14:11:23 -65.36903 49.95224      -31.614
15 20230718_GSL_SP1ST1_4k_01.MOV  14:11:24 -65.36899 49.95227      -31.272
16 20230718_GSL_SP1ST1_4k_01.MOV  14:11:25 -65.36898 49.95228      -31.189
17 20230718_GSL_SP1ST1_4k_01.MOV  14:11:26 -65.36897 49.95229      -31.102
18 20230718_GSL_SP1ST1_4k_01.MOV  14:11:27 -65.36896 49.95230      -31.015
19 20230718_GSL_SP1ST1_4k_01.MOV  14:11:28 -65.36895 49.95230      -30.927
20 20230718_GSL_SP1ST1_4k_01.MOV  14:11:29 -65.36894 49.95231      -30.838
21 20230718_GSL_SP1ST1_4k_01.MOV  14:11:30 -65.36899 49.95229      -32.265
22 20230718_GSL_SP1ST1_4k_01.MOV  14:11:31 -65.36901 49.95232      -31.533
23 20230718_GSL_SP1ST1_4k_01.MOV  14:11:32 -65.36901 49.95232      -31.781
24 20230718_GSL_SP1ST1_4k_01.MOV  14:11:33 -65.36900 49.95233      -31.921
25 20230718_GSL_SP1ST1_4k_01.MOV  14:11:34 -65.36899 49.95234      -32.056
26 20230718_GSL_SP1ST1_4k_01.MOV  14:11:35 -65.36898 49.95234      -32.188
27 20230718_GSL_SP1ST1_4k_01.MOV  14:11:36 -65.36897 49.95235      -32.320
28 20230718_GSL_SP1ST1_4k_01.MOV  14:11:37 -65.36896 49.95236      -32.452
29 20230718_GSL_SP1ST1_4k_01.MOV  14:11:38 -65.36901 49.95236      -31.729
30 20230718_GSL_SP1ST1_4k_01.MOV  14:11:39 -65.36901 49.95237      -31.705

Answer 1

我们可以做以下事情：

# Load libraries.

library(tidyverse)
library(sp)

# Using your sample data as `gps` find the cumulative distance.

gps_sp <- SpatialPoints(cbind(gps$lng,gps$lat))
test <- spDistsN1(gps_sp, gps_sp[1,], longlat=TRUE)

# Add output values to dataframe.

gps$test <- test

# Find rows that pass the 0.01 value thresholds.

thresholds <- seq(0.01, max(gps$test), by = 0.01)

threshold_indices <- as.data.frame(thresholds) %>%
  mutate(index = map(thresholds, ~which(gps$test >= .x)[1])) %>%
  unnest(cols = c(index))

# Add threshold column.

final_gps <- gps %>%
  mutate(row_id = row_number()) %>%
  mutate(passes_threshold = row_id %in% threshold_indices$index) %>%
  select(-row_id)

现在我们有一个列，如果达到阈值，则为 TRUE，否则为 FALSE。那么你可以这样做：

final_gps %>% 
  filter(passes_threshold == TRUE)

对于输出：

| filename                          | taken_at  | lng       | lat      | gps_altitude | test      | passes_threshold |
|-----------------------------------|-----------|-----------|----------|--------------|-----------|------------------|
| 20230718_GSL_SP1ST1_4k_01.MOV     | 14:11:20  | -65.36900 | 49.95225 | -31.328      | 0.01023953| TRUE             |
| 20230718_GSL_SP1ST1_4k_01.MOV     | 14:11:34  | -65.36899 | 49.95234 | -32.056      | 0.02007263| TRUE             |