Linearly interpolate values between two points

SO Link

Usage

interpolate(x, y, method = c("approx", "spline"))

Arguments

x, y

<numeric> vectors giving the coordinates of the points to be interpolated

method

<character> interpolation method, default is "approx"

Value

<numeric> vector of interpolated values

See also

Other base: colon()

Examples

interpolate(1:5, c(10, NA, NA, NA, 100), "spline")
#> [1]  10.0  32.5  55.0  77.5 100.0

df <- dplyr::tibble(
  seq = 1:5,
  v1 = c(1, NA, 3, NA, 5),
  v2 = c(40, NA, 60, NA, 70),
  v3 = c(10, NA, NA, NA, 100))

df
#> # A tibble: 5 × 4
#>     seq    v1    v2    v3
#>   <int> <dbl> <dbl> <dbl>
#> 1     1     1    40    10
#> 2     2    NA    NA    NA
#> 3     3     3    60    NA
#> 4     4    NA    NA    NA
#> 5     5     5    70   100

df |>
   dplyr::mutate(
   dplyr::across(
   .cols = dplyr::starts_with("v"),
   .fns = ~ interpolate(seq, .x),
   .names = "{.col}_est"))
#> # A tibble: 5 × 7
#>     seq    v1    v2    v3 v1_est v2_est v3_est
#>   <int> <dbl> <dbl> <dbl>  <dbl>  <dbl>  <dbl>
#> 1     1     1    40    10      1     40   10  
#> 2     2    NA    NA    NA      2     50   32.5
#> 3     3     3    60    NA      3     60   55  
#> 4     4    NA    NA    NA      4     65   77.5
#> 5     5     5    70   100      5     70  100  

df |>
  dplyr::mutate(
   dplyr::across(
    dplyr::starts_with("v"),
     ~ interpolate(seq, .x)))
#> # A tibble: 5 × 4
#>     seq    v1    v2    v3
#>   <int> <dbl> <dbl> <dbl>
#> 1     1     1    40  10  
#> 2     2     2    50  32.5
#> 3     3     3    60  55  
#> 4     4     4    65  77.5
#> 5     5     5    70 100