Question

我有一个my_cases <- list( Species == "setosa" ~ "S", TRUE ~ "other" ) tiris <- tibble::as_tibble(iris) tiris #> # A tibble: 150 x 5 #> Sepal.Length Sepal.Width Petal.Length Petal.Width Species #> <dbl> <dbl> <dbl> <dbl> <fct> #> 1 5.1 3.5 1.4 0.2 setosa #> 2 4.9 3 1.4 0.2 setosa #> 3 4.7 3.2 1.3 0.2 setosa #> 4 4.6 3.1 1.5 0.2 setosa #> 5 5 3.6 1.4 0.2 setosa #> 6 5.4 3.9 1.7 0.4 setosa #> 7 4.6 3.4 1.4 0.3 setosa #> 8 5 3.4 1.5 0.2 setosa #> 9 4.4 2.9 1.4 0.2 setosa #> 10 4.9 3.1 1.5 0.1 setosa #> # … with 140 more rows dplyr::mutate(tiris, new_label = dplyr::case_when(!!!my_cases) ) #> Error in eval_tidy(pair$lhs, env = default_env): object 'Species' not found devtools::session_info() #> ─ Session info ────────────────────────────────────────────────────────── #> setting value #> version R version 3.5.3 (2019-03-11) #> os macOS Mojave 10.14.3 #> system x86_64, darwin15.6.0 #> ui X11 #> language (EN) #> collate en_US.UTF-8 #> ctype en_US.UTF-8 #> tz America/New_York #> date 2019-03-31 #> #> ─ Packages ────────────────────────────────────────────────────────────── #> package * version date lib source #> assertthat 0.2.1 2019-03-21 [1] CRAN (R 3.5.3) #> backports 1.1.3 2018-12-14 [1] CRAN (R 3.5.0) #> callr 3.2.0 2019-03-15 [1] CRAN (R 3.5.1) #> cli 1.1.0 2019-03-19 [1] CRAN (R 3.5.1) #> crayon 1.3.4 2017-09-16 [1] CRAN (R 3.5.0) #> desc 1.2.0 2018-05-01 [1] CRAN (R 3.5.0) #> devtools 2.0.1 2018-10-26 [1] CRAN (R 3.5.3) #> digest 0.6.18 2018-10-10 [1] CRAN (R 3.5.0) #> dplyr 0.8.0.1 2019-02-15 [1] CRAN (R 3.5.2) #> evaluate 0.13 2019-02-12 [1] CRAN (R 3.5.2) #> fansi 0.4.0 2018-10-05 [1] CRAN (R 3.5.0) #> fs 1.2.7 2019-03-19 [1] CRAN (R 3.5.3) #> glue 1.3.1 2019-03-12 [1] CRAN (R 3.5.1) #> highr 0.8 2019-03-20 [1] CRAN (R 3.5.3) #> htmltools 0.3.6 2017-04-28 [1] CRAN (R 3.5.0) #> knitr 1.22 2019-03-08 [1] CRAN (R 3.5.2) #> magrittr 1.5 2014-11-22 [1] CRAN (R 3.5.0) #> memoise 1.1.0 2017-04-21 [1] CRAN (R 3.5.0) #> pillar 1.3.1 2018-12-15 [1] CRAN (R 3.5.0) #> pkgbuild 1.0.3 2019-03-20 [1] CRAN (R 3.5.3) #> pkgconfig 2.0.2 2018-08-16 [1] CRAN (R 3.5.0) #> pkgload 1.0.2 2018-10-29 [1] CRAN (R 3.5.0) #> prettyunits 1.0.2 2015-07-13 [1] CRAN (R 3.5.0) #> processx 3.3.0 2019-03-10 [1] CRAN (R 3.5.2) #> ps 1.3.0 2018-12-21 [1] CRAN (R 3.5.0) #> purrr 0.3.2 2019-03-15 [1] CRAN (R 3.5.1) #> R6 2.4.0 2019-02-14 [1] CRAN (R 3.5.2) #> Rcpp 1.0.1 2019-03-17 [1] CRAN (R 3.5.1) #> remotes 2.0.2 2018-10-30 [1] CRAN (R 3.5.0) #> rlang 0.3.3 2019-03-29 [1] CRAN (R 3.5.3) #> rmarkdown 1.12 2019-03-14 [1] CRAN (R 3.5.1) #> rprojroot 1.3-2 2018-01-03 [1] CRAN (R 3.5.0) #> sessioninfo 1.1.1 2018-11-05 [1] CRAN (R 3.5.0) #> stringi 1.4.3 2019-03-12 [1] CRAN (R 3.5.1) #> stringr 1.4.0 2019-02-10 [1] CRAN (R 3.5.2) #> testthat 2.0.1 2018-10-13 [1] CRAN (R 3.5.0) #> tibble 2.1.1 2019-03-16 [1] CRAN (R 3.5.1) #> tidyselect 0.2.5 2018-10-11 [1] CRAN (R 3.5.0) #> usethis 1.4.0 2018-08-14 [1] CRAN (R 3.5.0) #> utf8 1.1.4 2018-05-24 [1] CRAN (R 3.5.0) #> withr 2.1.2 2018-03-15 [1] CRAN (R 3.5.0) #> xfun 0.5 2019-02-20 [1] CRAN (R 3.5.2) #> yaml 2.2.0 2018-07-25 [1] CRAN (R 3.5.0) #> #> [1] /Library/Frameworks/R.framework/Versions/3.5/Resources/library，我想更改其特定像素（例如100 x 100像素）的图像。我怎样才能做到这一点？

Answer 1

您可以在该像素上添加一个矩形，并用一种颜色填充它：

var image: UIImage!
let color = UIColor.red
image = UIGraphicsImageRenderer(size: image.size).image { context in
    image.draw(at: .zero)
    let rectangle = CGRect(x: 100, y: 100, width: 1, height: 1)
    color.setFill()
    context.fill(rectangle)
}

或者您可能想将1 x 1像素的UIImage嵌入到其他UIImage中：

var onePixel: UIImage!
var image: UIImage!
image = UIGraphicsImageRenderer(size: image.size).image { context in
    image.draw(at: .zero)
    onePixel.draw(at: CGPoint(x: 100, y: 100))
}

或者您可能想将一个UIImage的像素移动到另一个UIImage：

var image1: UIImage!
var image2: UIImage!
// 1 x 1 size image, from position 100 x 100 of image2
var pixel: UIImage = UIGraphicsImageRenderer(bounds: CGRect(x: 100, y: 100, width: 1, height: 1)).image(actions: { _ in
    image2.draw(at: .zero)
})
// The image1 with the pixel image embed in the position 100 x 100
var image1WithPixel = UIGraphicsImageRenderer(size: image1.size).image { (_) in
    image1.draw(at: .zero)
    pixel.draw(at: CGPoint(x: 100, y: 100))
}

如何在UIImageView中更改单个像素的图像

1 个答案: