Extract matching rows of a data frame.
Match works in the same way as join, but instead of return the combined dataset, it only returns the matching rows from the first dataset. This is particularly useful when you've summarised the data in some way and want to subset the original data by a characteristic of the subset.
match_df(x, y, on = NULL)
x |
data frame to subset. |
y |
data frame defining matching rows. |
on |
variables to match on - by default will use all variables common to both data frames. |
the match criterion is ==, not identical).
it doesn't work for columns that are not atomic vectors
if there are no matches, the row will be omitted'
a data frame
# count the occurrences of each id in the baseball dataframe, then get the subset with a freq >25 longterm <- subset(count(baseball, "id"), freq > 25) # longterm # id freq # 30 ansonca01 27 # 48 baineha01 27 # ... # Select only rows from these longterm players from the baseball dataframe # (match would default to match on shared column names, but here was explicitly set "id") bb_longterm <- match_df(baseball, longterm, on="id") bb_longterm[1:5,]
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