How to calculate the proportion of females in two different groups in the same dataset?

In my data, I have a list of respondents who listed their age and gender. I have assigned a value of 1 of those who are 50+ in age. How would I calculate the proportion of females in the data in two different groups. respondents over 50 and respondents under 50?

My data (when selecting only relevant variables) looks like:

Gender    Age   fiftyplus
M         23      0
F         43      0
M         53      1 
M         50      1 
F         84      1
M         45      0 
F         79      1 

>Solution :

Here is one possible way to do it:

library(dplyr)

df %>% 
  count(Gender, fiftyplus) %>% 
  group_by(Gender) %>% 
  mutate(prop = prop.table(n))

  Gender fiftyplus     n  prop
  <chr>      <int> <int> <dbl>
1 F              0     1 0.333
2 F              1     2 0.667
3 M              0     2 0.5  
4 M              1     2 0.5  

data:

df <- structure(list(Gender = c("M", "F", "M", "M", "F", "M", "F"), 
    Age = c(23L, 43L, 53L, 50L, 84L, 45L, 79L), fiftyplus = c(0L, 
    0L, 1L, 1L, 1L, 0L, 1L)), class = "data.frame", row.names = c(NA, 
-7L))