Merge d296879 into 85c4430

CHANGES.rst

@@ -570,6 +570,8 @@ New Features
 - ``astropy.tests``
 
   - Added a new Quantity-aware ``assert_quantity_allclose``. [#3273]
+  - Added column alignment formatting for better pprint viewing
+    experience. [#3037]
 
 - ``astropy.time``
 

astropy/table/pprint.py

@@ -185,7 +185,7 @@ def _get_pprint_size(max_lines=None, max_width=None):
 
 
     def _pformat_col(self, col, max_lines=None, show_name=True, show_unit=None,
-                     show_dtype=False, show_length=None, html=False):
+                     show_dtype=False, show_length=None, html=False, align=None):
         """Return a list of formatted string representation of column values.
 
         Parameters
@@ -211,6 +211,11 @@ def _pformat_col(self, col, max_lines=None, show_name=True, show_unit=None,
         html : bool
             Output column as HTML
 
+        align : str or list
+            Left/right alignment of a column. Default is 'right'. A list
+            of strings can be provided for alignment of tables with multiple
+            columns.
+
         Returns
         -------
         lines : list
@@ -224,10 +229,14 @@ def _pformat_col(self, col, max_lines=None, show_name=True, show_unit=None,
             show_unit = getattr(col, 'unit', None) is not None
 
         outs = {}  # Some values from _pformat_col_iter iterator that are needed here
-        col_strs_iter = self._pformat_col_iter(col, max_lines, show_name=show_name, show_unit=show_unit,
-                                               show_dtype=show_dtype, show_length=show_length,
+        col_strs_iter = self._pformat_col_iter(col, max_lines, show_name=show_name,
+                                               show_unit=show_unit,
+                                               show_dtype=show_dtype,
+                                               show_length=show_length,
                                                outs=outs)
         col_strs = list(col_strs_iter)
+        if len(col_strs) > 0:
+            col_width = max(len(x) for x in col_strs)
 
         if html:
             from ..utils.xml.writer import xml_escape
@@ -249,6 +258,7 @@ def _pformat_col(self, col, max_lines=None, show_name=True, show_unit=None,
             col_strs.insert(0, '<table>')
             col_strs.append('</table>')
 
+        # Now bring all the column string values to the same fixed width        
         else:
             col_width = max(len(x) for x in col_strs) if col_strs else 1
 
@@ -258,10 +268,46 @@ def _pformat_col(self, col, max_lines=None, show_name=True, show_unit=None,
             if outs['i_dashes'] is not None:
                 col_strs[outs['i_dashes']] = '-' * col_width
 
-            # Now bring all the column string values to the same fixed width
+            # Format columns according to alignment
+            justify_methods = {'<': 'ljust', '^': 'center', '>': 'rjust'}
             for i, col_str in enumerate(col_strs):
-                col_strs[i] = col_str.rjust(col_width)
-
+                if align is None:
+                    try:
+                        if col.format[:2] == '0=':
+                            justify = (lambda col_str, col_width:
+                                       getattr(col_str, 'zfill')(col_width))
+                        else:
+                            justify_method = justify_methods.get(col.format[0], None)
+                            if justify_method is None:
+                                justify_method = justify_methods[col.format[1]]
+                                justify = (lambda col_str, col_width:
+                                           getattr(col_str, justify_method)(col_width,
+                                                                            col.format[0]))
+                            else:
+                                justify = (lambda col_str, col_width:
+                                           getattr(col_str, justify_method)(col_width))
+                    except:
+                        justify = (lambda col_str, col_width:
+                                   getattr(col_str, 'rjust')(col_width))
+                else:
+                    if align == '0=':
+                        justify = (lambda col_str, col_width:
+                                       getattr(col_str, 'zfill')(col_width))
+                    elif align in ['<','^','>']:
+                        justify_method = justify_methods.get(align, None)
+                        if justify_method is None:
+                            justify_method = justify_methods[col.format[1]]
+                            justify = (lambda col_str, col_width:
+                                       getattr(col_str, justify_method)(col_width,
+                                                                        col.format[0]))
+                        else:
+                            justify = (lambda col_str, col_width:
+                                       getattr(col_str, justify_method)(col_width))
+                    else:
+                        justify = (lambda col_str, col_width:
+                                   getattr(col_str, 'rjust')(col_width))
+                col_strs[i] = justify(col_str, col_width)
+
         if outs['show_length']:
             col_strs.append('Length = {0} rows'.format(len(col)))
 
@@ -376,7 +422,7 @@ def _pformat_col_iter(self, col, max_lines, show_name, show_unit, outs,
 
     def _pformat_table(self, table, max_lines=None, max_width=None, show_name=True,
                        show_unit=None, show_dtype=False,
-                       html=False, tableid=None):
+                       html=False, tableid=None, align='right'):
         """Return a list of lines for the formatted string representation of
         the table.
 
@@ -407,6 +453,11 @@ def _pformat_table(self, table, max_lines=None, max_width=None, show_name=True,
             "table{id}", where id is the unique integer id of the table object,
             id(table)
 
+        align : str or list
+            Left/right alignment of a column. Default is 'right'. A list
+            of strings can be provided for alignment of tables with multiple
+            columns.
+
         Returns
         -------
         out : str
@@ -423,12 +474,32 @@ def _pformat_table(self, table, max_lines=None, max_width=None, show_name=True,
         if show_unit is None:
             show_unit = any([getattr(col, 'unit', None) for col in six.itervalues(table.columns)])
 
-        for col in six.itervalues(table.columns):
-            lines, outs = self._pformat_col(col, max_lines, show_name=show_name,
-                                            show_unit=show_unit, show_dtype=show_dtype)
-            if outs['show_length']:
-                lines = lines[:-1]
-            cols.append(lines)
+        # Figure out align
+        if isinstance(align,str):
+            align = align
+        elif isinstance(align,list) and len(align) == 1:
+            align = align[0]
+        elif isinstance(align,list) and len(align) == len(table.columns.values()):
+            align = align
+        else:
+            align = 'right'
+
+        # If align remains a list, need to loop over values
+        if type(align) == list:
+            for i,col in enumerate(table.columns.values()):
+                lines, outs = self._pformat_col(col, max_lines, show_name=show_name,
+                                                show_unit=show_unit, show_dtype=show_dtype,
+                                                align=align[i])
+                if outs['show_length']:
+                    lines = lines[:-1]
+                cols.append(lines)
+        else:
+            for col in six.itervalues(table.columns):
+                lines, outs = self._pformat_col(col, max_lines, show_name=show_name,
+                                                show_unit=show_unit, show_dtype=show_dtype)
+                if outs['show_length']:
+                    lines = lines[:-1]
+                cols.append(lines)
 
         if not cols:
             return ['<No columns>'], {'show_length': False}

astropy/table/table.py

@@ -635,7 +635,7 @@ def _is_mixin_column(self, col, quantity_is_mixin=False):
         return is_mixin
 
     def pprint(self, max_lines=None, max_width=None, show_name=True,
-               show_unit=None, show_dtype=False):
+               show_unit=None, show_dtype=False, align='right'):
         """Print a formatted string representation of the table.
 
         If no value of ``max_lines`` is supplied then the height of the
@@ -666,14 +666,18 @@ def pprint(self, max_lines=None, max_width=None, show_name=True,
 
         show_dtype : bool
             Include a header row for column dtypes (default=True)
+
+        align : str
+            Left/right alignment of a column. Default is 'right'.
         """
         lines, outs = self.formatter._pformat_table(self, max_lines, max_width,
                                                     show_name=show_name, show_unit=show_unit,
-                                                    show_dtype=show_dtype)
+                                                    show_dtype=show_dtype, align=align)
         if outs['show_length']:
             lines.append('Length = {0} rows'.format(len(self)))
 
         n_header = outs['n_header']
+
         for i, line in enumerate(lines):
             if i < n_header:
                 color_print(line, 'red')
@@ -740,7 +744,8 @@ def show_in_browser(self,
                 webbrowser.get(browser).open("file://" + path)
 
     def pformat(self, max_lines=None, max_width=None, show_name=True,
-                show_unit=None, show_dtype=False, html=False, tableid=None):
+                show_unit=None, show_dtype=False, html=False, tableid=None,
+                align='right'):
         """Return a list of lines for the formatted string representation of
         the table.
 
@@ -781,16 +786,20 @@ def pformat(self, max_lines=None, max_width=None, show_name=True,
             "table{id}", where id is the unique integer id of the table object,
             id(self)
 
+        align : str
+            Left/right alignment of a column. Default is 'right'.
+
         Returns
         -------
         lines : list
             Formatted table as a list of strings
 
         """
+
         lines, outs = self.formatter._pformat_table(self, max_lines, max_width,
                                                     show_name=show_name, show_unit=show_unit,
                                                     show_dtype=show_dtype, html=html,
-                                                    tableid=tableid)
+                                                    tableid=tableid, align=align)
 
         if outs['show_length']:
             lines.append('Length = {0} rows'.format(len(self)))

astropy/table/tests/test_pprint.py

@@ -370,6 +370,19 @@ def test_column_format_func_not_str(self, table_type):
         with pytest.raises(ValueError):
             str(t['a'])
 
+    def test_column_alignment(self, table_type):
+        t = table_type([[1], [2], [3], [4]],
+                       names=('long title a', 'long title b',
+                              'long title c', 'long title d'))
+        t['long title a'].format = '<'
+        t['long title b'].format = '^'
+        t['long title c'].format = '>'
+        t['long title d'].format = '0='
+        assert str(t['long title a']) == 'long title a\n------------\n1           '
+        assert str(t['long title b']) == 'long title b\n------------\n     2      '
+        assert str(t['long title c']) == 'long title c\n------------\n           3'
+        assert str(t['long title d']) == 'long title d\n------------\n000000000004'
+
 
 class TestFormatWithMaskedElements():
 

docs/table/access_table.rst

@@ -374,6 +374,49 @@ For columns the syntax and behavior of
   2973.0
   Length = 100 rows
 
+Column alignment
+''''''''''''''''
+
+Individual columns have the ability to be aligned in a number of different
+ways, for an enhanced viewing experience.
+
+ >>> t1 = Table()
+ >>> t1['long column name 1'] = [1,2,3]
+ >>> t1['long column name 2'] = [4,5,6]
+ >>> t1['long column name 3'] = [7,8,9]
+ >>> t1['long column name 4'] = [700000,800000,900000]
+ >>> t1['long column name 2'].format = '<'
+ >>> t1['long column name 3'].format = '0='
+ >>> t1['long column name 4'].format = '^'
+ >>> t1.pprint()
+   long column name 1 long column name 2 long column name 3 long column name 4
+  ------------------ ------------------ ------------------ ------------------
+                   1 4                  000000000000000007       700000      
+                   2 5                  000000000000000008       800000      
+                   3 6                  000000000000000009       900000      
+
+Conveniently, alignment can be handled another way, by passing a list to the
+keyword argument ``align``.
+
+ >>> t1 = Table()
+ >>> t1['column1'] = [1,2,3,4,5]
+ >>> t1['column2'] = [2,4,6,8,10]
+ >>> t1.pprint(align=['<','0='])
+   column1 column2
+ ------- -------
+ 1       0000002
+ 2       0000004
+ 3       0000006
+ 4       0000008
+ 5       0000010
+
+By default, if the length of the list does not match the number of columns
+within the table, alignment defaults to right-aligned columns. This default
+behavior also holds true even if a single alignment character is passed in as a
+list (e.g., align=['^']), where global alignment of all columns within a table
+is intended. For very large tables, this can be a nuissance, and so looping is the
+recommended solution for this task.
+
 pformat() method
 ''''''''''''''''