How to update dataframe column using information from another dataframe

Question

I have 2 dataframes:

df1 = data.frame(Bird_ID = c(1:6), Sex = c("Male","Female","Male","Male","Male","UNK"))
df2 = data.frame(Bird_ID = c(6), Seen_sex = c("Female"))

df1
    # Bird_ID Sex
    # 1 Male
    # 2 Female
    # 3 Male
    # 4 Male
    # 5 Male
    # 6 UNK
    
    df2
    # Bird_ID Seen_Sex
    # 6 Female

• My first dataframe (df1) is my database where I have all my birds with known sex.
• My second dataframe (df2) is the "updater"

How can I update the bird 6 in df1 using information from df2? So "UNK" in df1 should become "Female" now and all other birds stay the same.

Answer 1

You may use match in base R -

df1$Sex[match(df2$Bird_ID, df1$Bird_ID)] <- df2$Seen_sex
df1

#  Bird_ID    Sex
#1       1   Male
#2       2 Female
#3       3   Male
#4       4   Male
#5       5   Male
#6       6 Female