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Support negative n in df.head() #972

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Merged
ehsantn merged 1 commit into from
Dec 11, 2025
Merged

Support negative n in df.head() #972

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4 changes: 4 additions & 0 deletions bodo/pandas/frame.py
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Original file line number Diff line number Diff line change
Expand Up @@ -310,6 +310,10 @@ def head(self, n: int = 5):
assert self._head_df is not None
return self._head_df.head(0).copy()

# Negative n like -1 is equivalent to df.iloc[:-1]
if n < 0:
n = max(0, len(self) + n)

if (self._head_df is None) or (n > self._head_df.shape[0]):
if bodo.dataframe_library_enabled and isinstance(
self._mgr, LazyMetadataMixin
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2 changes: 1 addition & 1 deletion bodo/pandas/series.py
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Original file line number Diff line number Diff line change
Expand Up @@ -604,7 +604,7 @@ def head(self, n: int = 5):
if n < 0:
# Convert the negative number of the number not to include to a positive number so the rest of the
# code can run normally. Unfortunately, this will likely require a plan execution here.
n = self.shape[0] + n
n = max(0, len(self) + n)

if n == 0 and self._head_s is not None:
if self._exec_state == ExecState.COLLECTED:
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