# [R] Color in stripchart

Gerrit Eichner gerr|t@e|chner @end|ng |rom m@th@un|-g|e@@en@de
Wed Mar 10 15:04:05 CET 2021

```Dear Robin,

if you study stripchart's code (graphics:::stripchart) carefully
you will find out that the elements of the vector provided to the
col-argument (and the pch-argument as well) are selected by iterating
along the groups (in your case year). I don't seen easy solution for
your problem using stripchart, but you may want to look at the
examples of function beeswarm in package beeswarm.

Hth  --  Gerrit

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Am 10.03.2021 um 14:08 schrieb Dr. Robin Haunschild:
> Dear fellow R users,
>
> I'd like to color individual points in a stripchart. This works well as
> long as I have only a single value per y axis category:
>
> df <- data.frame(year = seq(2011, 2018), value = seq(10,80, 10))
> df\$color <- 'black'
> df[df\$value<33,]\$color <- 'blue'
> df[df\$value>66,]\$color <- 'red'
> stripchart(df\$value ~ df\$year, pch=18, col=df\$color, method='stack')
>
> When I use multiple values per y axis category, all points in a specific
> y axis category have the same color:
>
> set.seed(20210310)
> years <- sample(x=seq(2011, 2018), size = 365*8, replace = TRUE)
> values <- sample(x=seq(0,100), size = 365*8, replace = TRUE)
> df <- data.frame(year = years, value = values)
> df\$color <- 'black'
> df[df\$value<33,]\$color <- 'blue'
> df[df\$value>66,]\$color <- 'red'
> stripchart(df\$value ~ df\$year, pch=18, col=df\$color, method='stack')
>
> I'd expect to see all points with a value below 33 in blue color, all
> points with a value above 66 in red color, and the remaining points in
> black color.
>
> I can use a black stripchart plot as basis and plot blue and red points
> over the black ones, but I do not get the stacking right:
>
> stripchart(df\$value ~ df\$year, pch=18, method='stack')
> points(df[df\$color=='blue',]\$value, df[df\$color=='blue',]\$year-2010,
> type='p', pch=18, col='blue')
> points(df[df\$color=='red',]\$value, df[df\$color=='red',]\$year-2010,
> type='p', pch=18, col='red')
>
> Am I somehow misusing the stripchart function?
>
>
> Best regards,
>
> Robin
>
>
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>

```

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