edponce commented on a change in pull request #12148:
URL: https://github.com/apache/arrow/pull/12148#discussion_r784329846
##########
File path: python/pyarrow/table.pxi
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@@ -1342,10 +1344,11 @@ cdef class Table(_PandasConvertible):
if preview_cols:
pieces.append('----')
for i in range(min(self.num_columns, preview_cols)):
- pieces.append('{}: {}'.format(
- self.field(i).name,
- self.column(i).to_string(indent=0, skip_new_lines=True)
- ))
+ col_string = self.column(i).to_string(
+ indent=0, skip_new_lines=True)
+ if len(col_string) > cols_char_limit:
+ col_string = col_string[:(cols_char_limit - 3)] + '...'
+ pieces.append('{}: {}'.format(self.field(i).name, col_string))
Review comment:
Ideally, we could always truncate "correctly" and consistently, that is,
truncate at a delimiter and show closing brackets: `[[1,2,3,4,...]]`
But several questions first:
* Is the delimiter always a comma or known in a variable?
* Is the table representation always encoded as a list of lists? Or can
there be a less/more nesting?
Assuming "yes" for the questions above. There are several cases that can
occur:
1. No truncation: `[[1,2,3,4]]`
2. Truncate does not reaches the final end bracket (# of brackets is
arbitrary): `[[1,2,3,4]...`
3. Truncate mid-value: `[10,20,30,4...`
3. Truncate at a value delimiter: `[[1,2,3,...`
4. Truncate at a list delimiter: `[[1,2,3,4],...`
5. Truncate at a list ending bracket: `[[1,2,3,4]...`
To display all truncated cases "correctly" and consistently, after slicing
the `cols_char_limit`, you would need
* a stack to keep track of open/close bracket pairs
* check which symbol is truncation occurring on.
Then resolve as follows:
* If it is a delimiter, then add `...` and match with closing brackets
* If it is a closing bracket
* and there are only closing bracket left, then add them to obtain the
full representation.
* add `...` and match with closing brackets
* Else it is truncating a value, so remove (or add) characters until
reaching a delimiter/bracket
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