datascience.tables.Table.set_format

Table.set_format(column_or_columns, formatter)

Set the pretty print format of a column(s) and/or convert its values.

Args:

column_or_columns: values to group (column label or index, or array)

formatter: a function applied to a single value within the

column_or_columns at a time or a formatter class, or formatter class instance.

Returns:

A Table with formatter applied to each column_or_columns.

The following example formats the column “balance” by passing in a formatter class instance. The formatter is run each time __repr__ is called. So, while the table is formatted upon being printed to the console, the underlying values within the table remain untouched. It’s worth noting that while set_format returns the table with the new formatters applied, this change is applied directly to the original table and then the original table is returned. This means set_format is what’s known as an inplace operation.

>>> account_info = Table().with_columns(
...    "user", make_array("gfoo", "bbar", "tbaz", "hbat"),
...    "balance", make_array(200, 555, 125, 430))
>>> account_info
user | balance
gfoo | 200
bbar | 555
tbaz | 125
hbat | 430
>>> from datascience.formats import CurrencyFormatter
>>> account_info.set_format("balance", CurrencyFormatter("BZ$")) # Belize Dollar
user | balance
gfoo | BZ$200
bbar | BZ$555
tbaz | BZ$125
hbat | BZ$430
>>> account_info["balance"]
array([200, 555, 125, 430])
>>> account_info
user | balance
gfoo | BZ$200
bbar | BZ$555
tbaz | BZ$125
hbat | BZ$430

The following example formats the column “balance” by passing in a formatter function.

>>> account_info = Table().with_columns(
...    "user", make_array("gfoo", "bbar", "tbaz", "hbat"),
...    "balance", make_array(200, 555, 125, 430))
>>> account_info
user | balance
gfoo | 200
bbar | 555
tbaz | 125
hbat | 430
>>> def iceland_krona_formatter(value):
...    return f"{value} kr"
>>> account_info.set_format("balance", iceland_krona_formatter)
user | balance
gfoo | 200 kr
bbar | 555 kr
tbaz | 125 kr
hbat | 430 kr

The following, formats the column “balance” by passing in a formatter class. Note the formatter class must have a Boolean converts_values attribute set and a format_column method that returns a function that formats a single value at a time. The format_column method accepts the name of the column and the value of the column as arguments and returns a formatter function that accepts a value and Boolean indicating whether that value is the column name. In the following example, if the if label: return value was removed, the column name “balance” would be formatted and printed as “balance kr”. The converts_values attribute should be set to False unless a convert_values method is also defined on the formatter class.

>>> account_info = Table().with_columns(
...    "user", make_array("gfoo", "bbar", "tbaz", "hbat"),
...    "balance", make_array(200, 555, 125, 430))
>>> account_info
user | balance
gfoo | 200
bbar | 555
tbaz | 125
hbat | 430
>>> class IcelandKronaFormatter():
...    def __init__(self):
...        self.converts_values = False
...
...    def format_column(self, label, column):
...        def format_krona(value, label):
...            if label:
...                return value
...            return f"{value} kr"
...
...        return format_krona
>>> account_info.set_format("balance", IcelandKronaFormatter)
user | balance
gfoo | 200 kr
bbar | 555 kr
tbaz | 125 kr
hbat | 430 kr
>>> account_info["balance"]
array([200, 555, 125, 430])

set_format can also be used to convert values. If you set the converts_values attribute to True and define a convert_column method that accepts the column values and returns the converted column values on the formatter class, the column values will be permanently converted to the new column values in a one time operation.

>>> account_info = Table().with_columns(
...    "user", make_array("gfoo", "bbar", "tbaz", "hbat"),
...    "balance", make_array(200.01, 555.55, 125.65, 430.18))
>>> account_info
user | balance
gfoo | 200.01
bbar | 555.55
tbaz | 125.65
hbat | 430.18
>>> class IcelandKronaFormatter():
...    def __init__(self):
...        self.converts_values = True
...
...    def format_column(self, label, column):
...        def format_krona(value, label):
...            if label:
...                return value
...            return f"{value} kr"
...
...        return format_krona
...
...    def convert_column(self, values):
...        # Drop the fractional kr.
...        return values.astype(int)
>>> account_info.set_format("balance", IcelandKronaFormatter)
user | balance
gfoo | 200 kr
bbar | 555 kr
tbaz | 125 kr
hbat | 430 kr
>>> account_info
user | balance
gfoo | 200 kr
bbar | 555 kr
tbaz | 125 kr
hbat | 430 kr
>>> account_info["balance"]
array([200, 555, 125, 430])

In the following example, multiple columns are configured to use the same formatter. Note the following formatter takes into account the length of all values in the column and formats them to be the same character length. This is something that the default table formatter does for you but, if you write a custom formatter, you must do yourself.

>>> account_info = Table().with_columns(
...    "user", make_array("gfoo", "bbar", "tbaz", "hbat"),
...    "checking", make_array(200, 555, 125, 430),
...    "savings", make_array(1000, 500, 1175, 6700))
>>> account_info
user | checking | savings
gfoo | 200      | 1000
bbar | 555      | 500
tbaz | 125      | 1175
hbat | 430      | 6700
>>> class IcelandKronaFormatter():
...    def __init__(self):
...        self.converts_values = False
...
...    def format_column(self, label, column):
...        val_width = max([len(str(v)) + len(" kr") for v in column])
...        val_width = max(len(str(label)), val_width)
...
...        def format_krona(value, label):
...            if label:
...                return value
...            return f"{value} kr".ljust(val_width)
...
...        return format_krona
>>> account_info.set_format(["checking", "savings"], IcelandKronaFormatter)
user | checking | savings
gfoo | 200 kr   | 1000 kr
bbar | 555 kr   | 500 kr
tbaz | 125 kr   | 1175 kr
hbat | 430 kr   | 6700 kr