Asked  7 Months ago    Answers:  5   Viewed   50 times

I'm currently using scale_brewer() for fill and these look beautiful in color (on screen and via color printer) but print relatively uniformly as greys when using a black and white printer. I searched the online ggplot2 documentation but didn't see anything about adding textures to fill colors. Is there an official ggplot2 way to do this or does anyone have a hack that they use? By textures I mean things like diagonal bars, reverse diagonal bars, dot patterns, etc that would differentiate fill colors when printed in black and white.



ggplot can use colorbrewer palettes. Some of these are "photocopy" friendly. So mabe something like this will work for you?

ggplot(diamonds, aes(x=cut, y=price, group=cut))+

in this case OrRd is a palette found on the colorbrewer webpage:

Photocopy Friendly: This indicates that a given color scheme will withstand black and white photocopying. Diverging schemes can not be photocopied successfully. Differences in lightness should be preserved with sequential schemes.

Tuesday, June 1, 2021
answered 7 Months ago

For simple situations like the exact example in the OP, I agree that Thierry's answer is the best. However, I think it's useful to point out another approach that becomes easier when you're trying to maintain consistent color schemes across multiple data frames that are not all obtained by subsetting a single large data frame. Managing the factors levels in multiple data frames can become tedious if they are being pulled from separate files and not all factor levels appear in each file.

One way to address this is to create a custom manual colour scale as follows:

#Some test data
dat <- data.frame(x=runif(10),y=runif(10),
        grp = rep(LETTERS[1:5],each = 2),stringsAsFactors = TRUE)

#Create a custom color scale
myColors <- brewer.pal(5,"Set1")
names(myColors) <- levels(dat$grp)
colScale <- scale_colour_manual(name = "grp",values = myColors)

and then add the color scale onto the plot as needed:

#One plot with all the data
p <- ggplot(dat,aes(x,y,colour = grp)) + geom_point()
p1 <- p + colScale

#A second plot with only four of the levels
p2 <- p %+% droplevels(subset(dat[4:10,])) + colScale

The first plot looks like this:

enter image description here

and the second plot looks like this:

enter image description here

This way you don't need to remember or check each data frame to see that they have the appropriate levels.

Tuesday, June 1, 2021
answered 7 Months ago

It's an R FAQ -- you need print() around it, or a ggsave() which is particular to ggplot2.

From the FAQ:

7.22 Why do lattice/trellis graphics not work?

The most likely reason is that you forgot to tell R to display the graph. Lattice functions such as xyplot() create a graph object, but do not display it (the same is true of ggplot2 graphics, and Trellis graphics in S-Plus). The print() method for the graph object produces the actual display. When you use these functions interactively at the command line, the result is automatically printed, but in source() or inside your own functions you will need an explicit print() statement.

Tuesday, June 15, 2021
answered 6 Months ago

vrajs5 you are not alone! We struggled with this issue. In our case we wanted to fill bar charts like in ggplot. This is the solution. You need to add specifically named columns, linked to your variables, to your data table for googleVis to pick up.

In my fill example, these are called roles, but once you see my syntax you can abstract it to annotations and other cool features. Google has them all documented here (check out superheroes example!) but it was not obvious how it applied to r.

@mages has this documented on this webpage, which shows features not in demo(googleVis):


# in this case
# How do we fill a bar chart showing bars depend on another variable? 
#   We wanted to show C in a different fill to other assets

library(data.table) # You can use data frames if you don't like DT

test.dt  = data.table(px = c("A","B","C"), py = c(1,4,9),
                      "" = c('silver', 'silver', 'gold'))

# Add your modifier to your chart as a new variable e.g.
test <-gvisBarChart(test.dt, 
                    xvar = "px",
                    yvar = c("py", ""),
                    options = list(legend = 'none'))

We have shown deterministically here, but you could code it to be dependent on your categories.

The secret is myvar.googleVis_thing_youneed linking the variable myvar to the googleVis feature.

RESULT BEFORE FILL (yvar = "py") GoogleVisBarChartBeforeRoleStyleExample

RESULT AFTER FILL (yvar = c("py", ""))


Take a look at mages examples (code also on Github) and you will have cracked the "categorization based on column values" issue.

Thursday, August 5, 2021
answered 4 Months ago

For loading texture files (png, jpg...) use this: (don't forget to install SDL and SDL_image libraries)

#include <SDL/SDL.h>
#include <SDL/SDL_image.h>

GLuint texture_alloc(const char  *tex_name, int alpha)
    GLuint tex_num;

    SDL_Surface *tex_img;
    glGenTextures(1, &tex_num);

    if(tex_img = (SDL_Surface *) IMG_Load(tex_name)) {

        glBindTexture(GL_TEXTURE_2D, tex_num);
        glTexParameteri(GL_TEXTURE_2D, GL_GENERATE_MIPMAP, GL_TRUE);

        if (alpha==1)
            glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, tex_img->w, tex_img->h, 0, GL_RGBA, GL_UNSIGNED_BYTE, tex_img->pixels);
            glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, tex_img->w, tex_img->h, 0, GL_RGB, GL_UNSIGNED_BYTE, tex_img->pixels);
        SDL_FreeSurface (tex_img);

    return tex_num;


For setting texture coordinates use glTexCoord function:

glTexCoord2f(0.0f, 0.0f);
glVertex3f( 1.0f, 1.0f,-1.0f); 
glTexCoord2f(1.0f, 0.0f);
glVertex3f(-1.0f, 1.0f,-1.0f);
Tuesday, October 5, 2021
answered 2 Months ago
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