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A clean and elegant way to print text tables in Python with minimal boilerplate code

Project description

nicetable

  • A clean and elegant way to print text tables in Python with minimal boilerplate code.
  • Built with modern Python, including type annotations. Requires Python 3.6 and up.

Basics

Typical usage includes:

  1. Import:
    from nicetable import NiceTable

  2. Create a NiceTable, providing a Listof column names.
    You can optionally pick a table layout, or override any formatting option:
    out = NiceTable(['Part ID','Weight(kg)'])
    out = NiceTable(['Part ID','Weight(kg)'], layout='grep')
    out = NiceTable(['Part ID','Weight(kg)'], layout='csv', header=False)

  3. Append new rows by calling append(), passing a List of values:
    out.append(my_list)
    out.append(['626kst/j8',1.37])

  4. Print:
    print(out)

Example

The class function NiceTable.supported_layouts() returns a List of [name, description] of all the builtin layouts.
This example uses NiceTable to print that list with the default table layout:

from nicetable.nicetable import NiceTable

out = NiceTable(['Layout', 'Description'])
for layout in NiceTable.builtin_layouts():
    out.append(layout)
print(out)

Output

+-----------+------------------------------------------------------------------------------------------------------+
|  Layout   |  Description                                                                                         |
+-----------+------------------------------------------------------------------------------------------------------+
|  csv      |  comma-separated values with a one-line header.                                                      |
|  default  |  fixed-width table with data auto-alignment.                                                         |
|  grep     |  tab-separated values with no header. Great for CLI output, easily post-processed by cut, grep etc.  |
|  md       |  for tables inside Markdown(.md) files, using the GFM table extension. Ex: README.md on github.      |
|  tsv      |  tab-separated values with a one-line header.                                                        |
+-----------+------------------------------------------------------------------------------------------------------+

Layouts and formatting settings

You can pick a table layout in the constructor, with the layout= parameter.
In addition, you can change the layout or override any other formatting settings at any time, if needed.
Internally, append() just stores the values as-is. The values are converted to strings only when the table is printed.

The next example uses the builtin NiceTable.SAMPLE_JSON, which returns some sample JSON data.
The code loops over a list of dictionaries, cherry-picking some values into the table columns. It prints the table, than changes the layout to csv and overrides a formatting option (changes the separator from , to |) before printing it again.

import json
from nicetable.nicetable import NiceTable

out = NiceTable(['Name', 'Type', 'Height(cm)', 'Weight(kg)'], layout='default')
for pokemon in json.loads(NiceTable.SAMPLE_JSON):
    out.append([pokemon['name'], pokemon['type'], pokemon['height'], pokemon['weight']])
print('-- default format --\n')
print(out)
out.layout = 'csv'
out.sep_vertical = '|'
print('-- CSV with a pipe separator --\n')
print(out)

Output:

-- default format --

+-------------+----------------+--------------+--------------+
|  Name       |  Type          |  Height(cm)  |  Weight(kg)  |
+-------------+----------------+--------------+--------------+
|  Bulbasaur  |  Grass/Poison  |          70  |       6.901  |
|  Pikachu    |  Electric      |          40  |       6.100  |
|  Mewtwo     |  Psychic       |         200  |     122.000  |
+-------------+----------------+--------------+--------------+

-- CSV with a pipe separator --

Name|Type|Height(cm)|Weight(kg)
Bulbasaur|Grass/Poison|70|6.901
Pikachu|Electric|40|6.1
Mewtwo|Psychic|200|122

Note that the default layout adjusts the column values with auto adjustment:

  1. Strings are aligned to the left, numbers are aligned to the right.
  2. In each numeric column, numbers are printed with the same number of fractional digits, so they align nicely.
    For example, the last column input is 6.901, 6.1 (float), 122 (int), all printed well-aligned.

Formatting settings

Table-level settings

You can override any table-level settings by assigning a value to their instance variable, for example:
out.header = False

Here is the list of formatting settings:

Setting Type Default Description
header bool True whether the table header will be printed
header_sepline bool True if the header is printed, whether a sepline will be printed after it
header_adjust str left adjust of the column names, one of ['left', 'center', 'right', 'compact']
sep_vertical str | a vertical separator string
sep_horizontal str - a horizontal separator string
sep_cross str + a crossing separator string (where vertical and horizontal separators meet)
border_top bool True whether the table top border will be printed
border_bottom bool True whether the table bottom border will be printed
border_left bool True whether the table left border will be printed
border_right bool True whether the table right border will be printed
cell_adjust str auto adjust of the values, one of ['auto', 'left', 'center', 'right', 'compact', 'strict_left', 'strict_center', 'strict_right']
cell_spacing int 2 number of spaces to add to each side of a value
value_min_len int 1 minimal string length of a value (shorter value will be space-padded)
value_none_string str N/A string representation of the None value
value_escape_type str ignore handling of sep_vertical inside a value, one of ['remove', 'replace', 'prefix', 'ignore']
value_escape_char str \ a string to replace or prefix sep_vertical, based on value_escape_type

The table above was generated by iterating on NiceTable.FORMATTING_SETTINGS and using the md layout:

from nicetable.nicetable import NiceTable

out = NiceTable(['Setting', 'Type', 'Default', 'Description'], layout='md')
for setting in NiceTable.FORMATTING_SETTINGS:
    out.append(setting)
out.set_col_adjust('Default', 'strict_left')
print(out)

Column-level settings

There are some column-level settings that you can control.
For each, you can specify the affected column by the column name or by the column position.

set_col_adjust(col, adjust)
sets an adjustment for a column. Overrides the table-level cell_adjust property.
out.set_col_adjust('Type','center') # set a by column name
out.set_col_adjust(1,'center') # set by position

set_col_func(col,function)
attach a pre-processing function to a column. The function will be applied to the value before it is being formatted.

import json
from nicetable.nicetable import NiceTable

out = NiceTable(['Name', 'Type', 'Height(cm)', ' Weight(kg)'], layout='default')
for pokemon in json.loads(NiceTable.SAMPLE_JSON):
    out.append([pokemon['name'], pokemon['type'], pokemon['height'], pokemon['weight']])
out.set_col_func(0, lambda x: x.upper())
out.set_col_func('Type', lambda x: x.lower() if x != 'Electric' else None)
print(out)

Output:

+-------------+----------------+--------------+---------------+
|  Name       |  Type          |  Height(cm)  |   Weight(kg)  |
+-------------+----------------+--------------+---------------+
|  BULBASAUR  |  grass/poison  |          70  |        6.901  |
|  PIKACHU    |  N/A           |          40  |        6.100  |
|  MEWTWO     |  psychic       |         200  |      122.000  |
+-------------+----------------+--------------+---------------+

The first column was changed to uppercase, the second to lowercase except one value that was assigned None, and therefore converted to value_none_string.

Others

get_column(col)
returns a List of the column values.

Adding a custom layout

To add a custom layout based on the existing options, you can inherit from NiceTable and define your own layout function.
The description of your function will be incorporated in the builtin_layouts() output

from nicetable.nicetable import NiceTable

class MyNiceTable(NiceTable):
    def _layout_as_winter_columns(self) -> None:
        """Table with a winter-themed separator. Quite Ugly."""
        self.sep_vertical = '❄☂🌧☂❄'
        self.sep_cross = '❄☂🌧☂❄'
        self.sep_horizontal = 'ˣ'


out = MyNiceTable(['Layout', 'Description'], layout='winter_columns')
for layout in MyNiceTable.builtin_layouts():
    out.append(layout)
print(out)

Output:

❄☂🌧☂❄ˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣ❄☂🌧☂❄ˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣ❄☂🌧☂❄
❄☂🌧☂❄  Layout          ❄☂🌧☂❄  Description                                                                                         ❄☂🌧☂❄
❄☂🌧☂❄ˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣ❄☂🌧☂❄ˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣ❄☂🌧☂❄
❄☂🌧☂❄  csv             ❄☂🌧☂❄  comma-separated values with a one-line header.                                                      ❄☂🌧☂❄
❄☂🌧☂❄  default         ❄☂🌧☂❄  fixed-width table with data auto-alignment.                                                         ❄☂🌧☂❄
❄☂🌧☂❄  grep            ❄☂🌧☂❄  tab-separated values with no header. Great for CLI output, easily post-processed by cut, grep etc.  ❄☂🌧☂❄
❄☂🌧☂❄  md              ❄☂🌧☂❄  for tables inside Markdown(.md) files, using the GFM table extension. Ex: README.md on github.      ❄☂🌧☂❄
❄☂🌧☂❄  tsv             ❄☂🌧☂❄  tab-separated values with a one-line header.                                                        ❄☂🌧☂❄
❄☂🌧☂❄  winter_columns  ❄☂🌧☂❄  Table with a winter-themed separator. Quite Ugly.                                                   ❄☂🌧☂❄
❄☂🌧☂❄ˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣ❄☂🌧☂❄ˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣˣ❄☂🌧☂❄

As you can see, the new layout and its description were added the output of builtin_layouts() of the new class.

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