[r] how to realize countifs function (excel) in R

Here an example with 100000 rows (occupations are set here from A to Z):

> a = data.frame(sex=sample(c("M", "F"), 100000, replace=T), occupation=sample(LETTERS, 100000, replace=T))
> sum(a$sex == "M" & a$occupation=="A")
[1] 1882

returns the number of males with occupation "A".

EDIT

As I understand from your comment, you want the counts of all possible combinations of sex and occupation. So first create a dataframe with all combinations:

combns = expand.grid(c("M", "F"), LETTERS)

and loop with apply to sum for your criteria and append the results to combns:

combns = cbind (combns, apply(combns, 1, function(x)sum(a$sex==x[1] & a$occupation==x[2])))
colnames(combns) = c("sex", "occupation", "count")

The first rows of your result look as follows:

  sex occupation count
1   M          A  1882
2   F          A  1869
3   M          B  1866
4   F          B  1904
5   M          C  1979
6   F          C  1910

Does this solve your problem?

OR:

Much easier solution suggested by thelatemai:

table(a$sex, a$occupation)


       A    B    C    D    E    F    G    H    I    J    K    L    M    N    O
  F 1869 1904 1910 1907 1894 1940 1964 1907 1918 1892 1962 1933 1886 1960 1972
  M 1882 1866 1979 1904 1895 1845 1946 1905 1999 1994 1933 1950 1876 1856 1911

       P    Q    R    S    T    U    V    W    X    Y    Z
  F 1908 1907 1883 1888 1943 1922 2016 1962 1885 1898 1889
  M 1928 1938 1916 1927 1972 1965 1946 1903 1965 1974 1906