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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) and has an extensive test suite. Requires Python 3.6 and up.

Typical usage

  1. Import:
    from nicetable.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, NiceTable stores the values as-is, and generates formatted strings from them 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 automatically identify numeric columns and print them well-aligned to the right (see next section).
For example, the last column input was 6.901, 6.1 (float), 122 (int), as can be seen in the csv output.

Cell adjustment

  • Cell contents can be adjusted left, center or right, and are space-padded to the width of the longest value in the column (see also next section on wrapping).
    Alternatively, cell contents can be kept as-is with compact adjustment, though it means that the table vertical lines will not align (this is used in some layouts such as csv).
  • The default adjustment is auto, meaning that numeric columns (those with only numbers or None values) are adjusted right, and non-numeric columns are adjusted left.
  • Numeric columns automatically well-aligned, meaning all their ones digit are printed in the same position.
    To print them as strings, add a strict_ prefix to the adjust, like strict_left. For example:
+-----------------+-------------------+------------------+---------------+-----------------+----------------+
|  standard left  |  standard center  |  standard right  |  strict_left  |  strict_center  |  strict_right  |
+-----------------+-------------------+------------------+---------------+-----------------+----------------+
|    6.901        |        6.901      |           6.901  |  6.901        |      6.901      |         6.901  |
|    6.000        |        6.000      |           6.000  |  6            |        6        |             6  |
|    1.000        |        1.000      |           1.000  |  1            |        1        |             1  |
|  122.000        |      122.000      |         122.000  |  122          |       122       |           122  |
+-----------------+-------------------+------------------+---------------+-----------------+----------------+

The example above uses long column names on purpose, otherwise left, center and right would look the same, as all the numbers in each column have the same fixed width (based on their longest column value).

Text wrapping and newlines

NiceTable supports handling long values and newlines in both column names and cell values.

Text wrapping

When a value is longer than value_max_len, it handled by a value_too_long_policy policy.
The default policy is wrap, which means the value will be broken to multiple lines every value_max_len characters.
Alternatively, specify the truncate policy to have to values truncated.
The following examples demonstrates the two policies:

out = NiceTable(['Code', 'Product Description(Long)'])
out.append([1, 'Boeing 777. Batteries not included. May contain nuts.'])
out.append([2, 'Sack of sand'])
print(out)
out.value_max_len = 19
print(out)
out.value_too_long_policy = 'truncate'
print(out)

Output:

+--------+---------------------------------------------------------+
|  Code  |  Product Description(Long)                              |
+--------+---------------------------------------------------------+
|     1  |  Boeing 777. Batteries not included. May contain nuts.  |
|     2  |  Sack of sand                                           |
+--------+---------------------------------------------------------+

+--------+-----------------------+
|  Code  |  Product Description  |
|        |  (Long)               |
+--------+-----------------------+
|     1  |  Boeing 777. Batteri  |
|        |  es not included. Ma  |
|        |  y contain nuts.      |
|     2  |  Sack of sand         |
+--------+-----------------------+

+--------+-----------------------+
|  Code  |  Product Description  |
+--------+-----------------------+
|     1  |  Boeing 777. Batteri  |
|     2  |  Sack of sand         |
+--------+-----------------------+

Newlines

When newlines are encountered in a column name or a value, they by default cause the text to wrap. Alternatively, you can ask that newlines will be replaced, by setting value_newline_replace to an alternative string (default is None).
The following example first shows the default behavior, and than shows replacing newlines with the string \n:

out = NiceTable(['Code', 'Product Description\n(Long)']) \
    .append([1, 'Boeing 777\nBatteries not included.\nMay contain nuts.']) \
    .append([2, 'Sack of sand'])
print(out)
out.value_newline_replace = '\\n'
print(out)

Output:

+--------+---------------------------+
|  Code  |  Product Description      |
|        |  (Long)                   |
+--------+---------------------------+
|     1  |  Boeing 777               |
|        |  Batteries not included.  |
|        |  May contain nuts.        |
|     2  |  Sack of sand             |
+--------+---------------------------+

+--------+----------------------------------------------------------+
|  Code  |  Product Description\n(Long)                             |
+--------+----------------------------------------------------------+
|     1  |  Boeing 777\nBatteries not included.\nMay contain nuts.  |
|     2  |  Sack of sand                                            |
+--------+----------------------------------------------------------+

Escaping

TODO...
value_escape_type
value_escape_char

Table-level settings

Below is the list of the table-level settings, which you can directly set. For example: out.header = False

Setting Type Default Description
header bool 1 whether the table header will be printed
header_sepline bool 1 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 1 whether the table top border will be printed
border_bottom bool 1 whether the table bottom border will be printed
border_left bool 1 whether the table left border will be printed
border_right bool 1 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 values will be space-padded
value_max_len int 9999 maximum string length of a value
value_too_long_policy str wrap handling of a string longer than value_max_len, one of: ['truncate', 'wrap']
value_newline_replace str None if set, replace newlines in string value with this
value_none_string str None 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
value_func function None a function to pre-process the value before any other settings apply

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)
print(out)

Column-level settings

The set_col_options() function sets allows you to set the following settings at the column-level:

Parameter Meaning
adjust overrides the table-wide cell_adjust
max_len overrides the table-wide value_max_len
newline_replace overrides the table-wide value_newline_replace
none_string overrides the table-wide value_none_string
func overrides the table-wide value_func

This function accepts either a column name or a column position for the first parameter. For example:

import json
from nicetable.nicetable import NiceTable

out = NiceTable(['Name', 'Type', 'Height(cm)', ' Weight(kg)'])
for pokemon in json.loads(NiceTable.SAMPLE_JSON):
    out.append([pokemon['name'], pokemon['type'], pokemon['height'], pokemon['weight']])

# set the first column options by position
out.set_col_options(0, adjust='center')

# set the second column options by column name
out.set_col_options('Type',
                    func=lambda x: x.lower() if x != 'Electric' else None,
                    none_string = 'N/A')
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  |
+-------------+----------------+--------------+---------------+

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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