Type & Coercion Errors

Join type mismatch

Matches: Can't join on .* incompatible types

WHAT THIS ERROR MEANS

You tried to join two data frames on a column, but the column has different types in each data frame (e.g., character vs numeric).

1. Check column types in both data frames with str() or class().

2. Convert one to match the other before joining.

3. Use mutate() to coerce the join column.

BAD — THIS CAUSES THE ERROR

# df1$id is numeric, df2$id is character
left_join(df1, df2, by = "id")

GOOD — CORRECT APPROACH

df2 <- df2 %>% mutate(id = as.numeric(id))
left_join(df1, df2, by = "id")

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