如何计算R空间中定义区域内的值？

Question

I have data which looks like this:

   identity  growth x-pos y-pos
1:     Z      0.1   0.5   0.7
2:     B      0.1   0.1   0.0
3:     C      0.2   4.6   2.5
4:     D      0.3   5.6   5.0
5:     A      0.4   0.2   1.0
6:     P      0.1   0.4   2.0

Here, the each object with a unique identity is positioned on a 2d plane and the coordinates are denoted by x-pos y-pos (in micrometers) and has a certain growth value.

What I want to do for every unique row or object having unique identity is this: 1.Compute the number of other objects with a unique identity within a circle of a specific radius (for eg. 2 micrometers) using the spatial coordinates. For instance, for object Z there are a certain number of other objects within a 2 micrometer radius. 2. Compute the mean of growth values for all objects within a certain radius from a focal object. Ideally, I want to do this for all unique objects and make a new data frame where

   identity  mean_ growth_2micrometers mean_growth_4micrometers mean_growth_6micrometers 
1:     Z      0.1                      0.5                      0.7
2:     B      0.1                      0.1                      0.4
3:     C      0.2                      0.6                      0.5

Answer 1

dist can be used to get the distance between all points. Use this to identify which points are within the desired distance.

library(tidyverse)

df %>%
  select(`x-pos`, `y-pos`) %>%
  dist(diag = TRUE, upper = TRUE) %>%
  as.matrix() %>%
  as_tibble() %>%
  set_names(df$identity) %>%
  mutate(
    identity = df$identity
  ) %>%
  pivot_longer(cols = 1:6) %>%
  inner_join(df %>% select(name=identity, growth)) %>%
  group_by(identity) %>%
  summarise(
    mean_growth_2micrometers = mean(ifelse(value < 2, growth, NA), na.rm = TRUE),
    mean_growth_4micrometers = mean(ifelse(value < 4, growth, NA), na.rm = TRUE),
    mean_growth_6micrometers = mean(ifelse(value < 6, growth, NA), na.rm = TRUE)
  )
#> # A tibble: 6 x 4
#>   identity mean_growth_2micrometers mean_growth_4micrometers mean_growth_6micrometers
#>   <chr>                       <dbl>                    <dbl>                    <dbl>
#> 1 A                           0.175                    0.175                     0.18
#> 2 B                           0.2                      0.175                     0.18
#> 3 C                           0.2                      0.25                      0.2 
#> 4 D                           0.3                      0.25                      0.25
#> 5 P                           0.2                      0.175                     0.18
#> 6 Z                           0.175                    0.175                     0.18