As the red line clearly demonstrates, ...

      I have been at lots of business meetings where the speaker would say something like, "As the red line clearly demonstrates, ..."

      I would quickly look up at two particular co-workers. We all had that same rolling of the eyes look. When you have color-challenged issues, that red line does not clearly demonstrate anything to us. (And yes, the three of us knew we all had color issues.)

      I wrote the R code for this graph. But I used a random number to decide which line is red and which is green, so I don't know which line is which.

      I am not color-blind. I am color-challenged. I see some colors, but probably not as many as most people see. I don't distinguish between red and green well. I also don't distinguish between blue and purple well because of the red element of purple, and similarly for other combinations.

      In my earliest elementary school years I had a box of 8 Crayola crayons, and I did just fine. My problems began when Crayola started adding more and more colors including combinations like green yellow and yellow green. Here are the original eight colors, which I still identify just fine. (There is no meaning to the heights of the bars.)

      One source suggests approximately 1 in 12 men have color issues, but only 1 in 200 women.

      Color-challenged people often have coping strategies. I can see when the top traffic light is on, so I will stop my car. But in my heart, I don't think it is red, but more of an orange. Similarly I can see when the bottom traffic light is on, but I think it is more of an off-white than green. As long as no one flips the positions, I am fine. A single flashing light is a probllem though.

      When I see an 8-sided stop sign, that's what I consider red. And I recognize Taylor Swift wears what I consider a very red lipstick, but I assume she wears more than one shade and I cannot distinguish among them.

      The speaker with the two-line graph could have used the different shapes, or different graph line types dashes and dots, in the talk. Or the speaker could have used color-blind friendly color palettes. If you are creating visualizations for others, please think about these things.

      And ladies, that purple lipstick looks very nice on you. Oh, it's not purple ... ?

      The R code is as follows:

# Two lines with random colors
x <- seq(1:5)
y <- seq(1:5)
z <- seq(5,1, by = -1)

color_1 <- "#00B050"
color_2 <- "#FF0000" 

r <- runif(1,0,1)
r
if (r < .5){
  col_y <- color_1
  col_z <- color_2
} else{
  col_y <- color_2
  col_z <- color_1
}

plot(x,y, type="b", pch = 18, cex = 2.5, lwd = 2.5, col=col_y, ylab="", xlab="", 
     main="As the red line clearly demonstrates ...", cex.main = 1.5,
     sub="If r<.5 then (green, red), else (red, green)",
     font.sub = 2, cex.sub = 1.5)
par(new=TRUE)
plot(x,z, type="b", pch=20, cex = 2.5, lwd = 2.5, col=col_z, ylab="", xlab="")
legend("topright", legend= c("Increasing", "Decreasing"), pch = c(18, 20),
       col = c(col_y, col_z), cex=1.5, text.font=2)

# Original 8 Crayola Crayons
title <- c("Original 8 Crayola Crayons")
subtitle <- c("According to https://en.wikipedia.org/wiki/History_of_Crayola_crayons")
temp <- c(5,7,6,4,8,5,2,5)  # meaningless
colors <- c("red", "yellow", "blue", "green", "orange", "brown", "violet", "black")
hex <- c("#FF0000", "#FFFF00", "#0000FF", "#008001", "#FF6600", "#964B00", "#6A0DAD", "#000000")
barplot(temp, col=hex, main=title, sub=subtitle, names.arg=colors,
          cex.main = 1.5, font.axis = 2, font.sub = 2, cex.sub = .75 )
       

End