stacked barplot in r using ggplot

Question

These are my questions:

1. How can I change the colours of the stacked to more distinguished colours.
2. Adding the values on the stacked
3. modifying my legend and the name of the legend.

I really tried everything so far and also looked at almost all videos on stacked bar plot, but without having been able to do it. Something is lacking me.
I will really appreciate your help.

datt <- read.table(text = " Architektur   Biologie   Mathematik                       
Baden-Württemberg             4342     7109       7909
Bayern                        4377     7295       7014
Berlin                        2929     2969       3449
Brandenburg                   1148      982        825
Bremen                         427      877        738
Hamburg                        574     1513        506
Hessen                        5155     4426       7617
Mecklenburg-Vorpommern         445     1468        537
Niedersachsen                 3102     5353       5464
Nordrhein-Westfalen           9453    14356      18247
Rheinland-Pfalz               1916     2907       3235
Saarland                       296      381        334
Sachsen                       1182     1354       1521
Sachsen-Anhalt                 758      543        349
Schleswig-Holstein             438     1239       1336
Thüringen                     1796      921        445                
" , header = TRUE)


library(reshape2)
#Zeile
datt$row <- seq_len(nrow(datt))
#
ww<- melt(datt, id.vars = "row")
ww
library(ggplot2)

ggplot(ww , aes(x = variable, y = value, fill = row) ) + 
  geom_bar( stat = "identity") +
  xlab("\nStudienfach WS2019/20") + ylab("Absolute Häufigkeit\n")  +
 
 ggtitle("Drei Studiengängen in den verschiedenen Bundesländern WS2019/22")+
  theme(plot.title = element_text(hjust=0.5))
+ geom_text(size=3,position = position_stack(vjust = 0.5)) 

picture of bar-plot

Answer 1

From looking at your data, you should be using row names as categorical variables rather than row numbers, which will be treated as a numeric variable with a gradient fill. This will automatically make the colors more "separated", though you will always have limited color separation with 16 items. It will also label your legend appropriately.

For adding labels to each segment, just add aes(label = value) to geom_text.

To change the name of your fill scale to "Bundesländ", use labs(fill = "Bundesländ")

library(reshape2)
library(ggplot2)

ggplot(melt(within(datt, row <- row.names(datt)), id.vars = "row"), 
       aes(x = variable, y = value, fill = row)) + 
  geom_col(size = 0.5, col = "gray50") +
  geom_text(aes(label = value), size = 3,
            position = position_stack(vjust = 0.5)) +
  xlab("\nStudienfach WS2019/20") + 
  ylab("Absolute Häufigkeit\n") +
  labs(fill = "Bundesländ") +
  ggtitle("Drei Studiengängen in den verschiedenen Bundesländern WS2019/22") +
  theme_bw(base_size = 16) +
  theme(plot.title = element_text(hjust = 0.5))