R - calculate annual population conditional on survival in every year - r

Question

I have a data frame with three columns: birth_year, death_year, gender.
I have to calculate total alive male and female population for every year in a given range (1950:1980).
The data frame looks like this:
birth_year death_year gender
1934 1988 male
1922 1993 female
1890 1966 male
1901 1956 male
1946 2009 female
1909 1976 female
1899 1945 male
1887 1949 male
1902 1984 female
The person is alive in year x if death_year > x & birth year <= x
The output I am looking for is something like this:
year male female
1950 3 4
1951 2 3
1952 4 3
1953 4 5
.
.
1980 6 3
Thanks!

Answer 1

Does this work:
library(tidyr)
library(purrr)
library(dplyr)
df %>% mutate(year = map2(1950,1980, seq)) %>% unnest(year) %>%
mutate(isalive = case_when(year >= birth_year & year < death_year ~ 1, TRUE ~ 0)) %>%
group_by(year, gender) %>% summarise(alive = sum(isalive)) %>%
pivot_wider(names_from = gender, values_from = alive) %>% print( n = 50)
`summarise()` regrouping output by 'year' (override with `.groups` argument)
# A tibble: 31 x 3
# Groups: year [31]
year female male
<int> <dbl> <dbl>
1 1950 4 3
2 1951 4 3
3 1952 4 3
4 1953 4 3
5 1954 4 3
6 1955 4 3
7 1956 4 2
8 1957 4 2
9 1958 4 2
10 1959 4 2
11 1960 4 2
12 1961 4 2
13 1962 4 2
14 1963 4 2
15 1964 4 2
16 1965 4 2
17 1966 4 1
18 1967 4 1
19 1968 4 1
20 1969 4 1
21 1970 4 1
22 1971 4 1
23 1972 4 1
24 1973 4 1
25 1974 4 1
26 1975 4 1
27 1976 3 1
28 1977 3 1
29 1978 3 1
30 1979 3 1
31 1980 3 1
Data used:
df
# A tibble: 9 x 3
birth_year death_year gender
<dbl> <dbl> <chr>
1 1934 1988 male
2 1922 1993 female
3 1890 1966 male
4 1901 1956 male
5 1946 2009 female
6 1909 1976 female
7 1899 1945 male
8 1887 1949 male
9 1902 1984 female

Answer 2

Here's a simple base R solution. Summing a logical vector will get you your count of alive or dead because TRUE is 1 and FALSE is 0.
number_alive <- function(range, df){
sapply(range, function(x) sum((df$death_year > x) & (df$birth_year <= x)))
}
output <- data.frame('year' = 1950:1980,
'female' = number_alive(1950:1980, df[df$gender == 'female']),
'male' = number_alive(1950:1980, df[df$gender == 'male']))
# year female male
# 1 1950 4 3
# 2 1951 4 3
# 3 1952 4 3
# 4 1953 4 3
# 5 1954 4 3
# 6 1955 4 3
# 7 1956 4 2
# 8 1957 4 2
# 9 1958 4 2
# 10 1959 4 2
# 11 1960 4 2
# 12 1961 4 2
# 13 1962 4 2
# 14 1963 4 2
# 15 1964 4 2
# 16 1965 4 2
# 17 1966 4 1
# 18 1967 4 1
# 19 1968 4 1
# 20 1969 4 1
# 21 1970 4 1
# 22 1971 4 1
# 23 1972 4 1
# 24 1973 4 1
# 25 1974 4 1
# 26 1975 4 1
# 27 1976 3 1
# 28 1977 3 1
# 29 1978 3 1
# 30 1979 3 1
# 31 1980 3 1

Answer 3

This approach uses an ifelse to determine if alive (1) or dead (0).
Data:
df <- "birth_year death_year gender
1934 1988 male
1922 1993 female
1890 1966 male
1901 1956 male
1946 2009 female
1909 1976 female
1899 1945 male
1887 1949 male
1902 1984 female"
df <- read.table(text = df, header = TRUE)
Code:
library(dplyr)
library(tidyr)
library(tibble)
library(purrr)
df %>%
mutate(year = map2(1950,1980, seq)) %>%
unnest(year) %>%
select(year, birth_year, death_year, gender) %>%
mutate(
alive = ifelse(year >= birth_year & year <= death_year, 1, 0)
) %>%
group_by(year, gender) %>%
summarise(
is_alive = sum(alive)
) %>%
pivot_wider(
names_from = gender,
values_from = is_alive
) %>%
select(year, male, female)
Output:
#> # A tibble: 31 x 3
#> # Groups: year [31]
#> year male female
#> <int> <dbl> <dbl>
#> 1 1950 3 4
#> 2 1951 3 4
#> 3 1952 3 4
#> 4 1953 3 4
#> 5 1954 3 4
#> 6 1955 3 4
#> 7 1956 3 4
#> 8 1957 2 4
#> 9 1958 2 4
#> 10 1959 2 4
#> # … with 21 more rows
Created on 2020-11-11 by the reprex package (v0.3.0)