Perform a merge for ordered data with optional filling/interpolation.
Designed for ordered data like time series data. Optionally perform group-wise merge (see examples).
First pandas object to merge.
Second pandas object to merge.
Field names to join on. Must be found in both DataFrames.
Field names to join on in left DataFrame. Can be a vector or list of vectors of the length of the DataFrame to use a particular vector as the join key instead of columns.
Field names to join on in right DataFrame or vector/list of vectors per left_on docs.
Group left DataFrame by group columns and merge piece by piece with right DataFrame. Must be None if either left or right are a Series.
Group right DataFrame by group columns and merge piece by piece with left DataFrame. Must be None if either left or right are a Series.
Interpolation method for data.
A length-2 sequence where each element is optionally a string indicating the suffix to add to overlapping column names in left and right respectively. Pass a value of None instead of a string to indicate that the column name from left or right should be left as-is, with no suffix. At least one of the values must not be None.
left: use only keys from left frame (SQL: left outer join)
right: use only keys from right frame (SQL: right outer join)
outer: use union of keys from both frames (SQL: full outer join)
inner: use intersection of keys from both frames (SQL: inner join).
The merged DataFrame output type will be the same as âleftâ, if it is a subclass of DataFrame.
See also
merge
Merge with a database-style join.
merge_asof
Merge on nearest keys.
Examples
>>> from pandas import merge_ordered >>> df1 = pd.DataFrame( ... { ... "key": ["a", "c", "e", "a", "c", "e"], ... "lvalue": [1, 2, 3, 1, 2, 3], ... "group": ["a", "a", "a", "b", "b", "b"], ... } ... ) >>> df1 key lvalue group 0 a 1 a 1 c 2 a 2 e 3 a 3 a 1 b 4 c 2 b 5 e 3 b
>>> df2 = pd.DataFrame({"key": ["b", "c", "d"], "rvalue": [1, 2, 3]}) >>> df2 key rvalue 0 b 1 1 c 2 2 d 3
>>> merge_ordered(df1, df2, fill_method="ffill", left_by="group") key lvalue group rvalue 0 a 1 a NaN 1 b 1 a 1.0 2 c 2 a 2.0 3 d 2 a 3.0 4 e 3 a 3.0 5 a 1 b NaN 6 b 1 b 1.0 7 c 2 b 2.0 8 d 2 b 3.0 9 e 3 b 3.0
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