TableReport JSON schema

TableReport.json() returns a JSON string whose top-level object contains the keys described below.

Top-level object

Key	Type	Description
dataframe_module	string	Name of the dataframe library used. Either "pandas" or "polars".
n_rows	integer	Number of rows in the dataframe.
n_columns	integer	Number of columns in the dataframe.
dataframe_is_empty	boolean	true when the dataframe has no rows or no columns.
plots_skipped	boolean	true when plot_distributions=False was passed to TableReport. When true, plot keys are absent from column objects, but histogram_data is still present for numeric and datetime columns.
associations_skipped	boolean	true when association computation was skipped (either because with_associations=False was passed, or because polars was used without pyarrow installed).
cardinality_threshold	integer	The threshold from get_config() above which a column is considered high-cardinality. Default: 40.
n_constant_columns	integer	Number of columns whose values are all identical.
columns	array of column objects	One entry per column, in the original column order.
top_associations	array of association objects	Column-pair association scores (up to 1 000 pairs, sorted by strength). Present only when associations_skipped is false.
title	string	Optional. Present only when a title argument was passed to TableReport.
order_by	string	Optional. Name of the column used for sorting when the deprecated parameter order_by was passed to TableReport.

Column object

Every entry in columns contains the following keys. Additional keys are present depending on the column’s dtype; they are documented in the subsections below.

Key	Type	Description
position	integer	Zero-based index of the column in the dataframe (same as idx).
idx	integer	Zero-based index of the column in the dataframe (same as position).
name	string	Column name.
dtype	string	Column dtype as a string (e.g. "float64", "object", "datetime64[ns]").
null_count	integer	Number of null / NaN values.
null_proportion	number	Fraction of null values in [0, 1].
nulls_level	string	Summary severity level: "ok" (no nulls), "warning" (some nulls), or "critical" (all values are null).
value_is_constant	boolean	true when every non-null value in the column is identical.
is_ordered	boolean	true when the column values are sorted in ascending or descending order.
plot_names	array of strings	Names of the plot keys that are present on this column object (e.g. ["histogram_plot"]). Empty when plots_skipped is true or when the column is constant or contains only nulls.

Columns containing only nulls

When null_count equals n_rows (all values are null) only the keys of the base column object above are present; no statistical keys are added.

Categorical / string columns

Present for non-numeric, non-datetime, non-duration columns that are not entirely null.

Key	Type	Description
n_unique	integer	Number of distinct values (including null).
unique_proportion	number	Fraction of distinct values relative to n_rows.
is_high_cardinality	boolean	true when n_unique exceeds cardinality_threshold.
value_counts	array of [value, count] pairs	The up to 10 most frequent values and their counts, sorted by frequency descending. Each element is a two-element array [value, count] where value is a string and count is an integer.
most_frequent_values	array of strings	The up to 10 most frequent values (same order as value_counts).
constant_value	any	Optional: Present only when value_is_constant is true. The single value shared by all non-null rows.
value_counts_plot	string (SVG)	Optional: Present only when plots_skipped is false and value_is_constant is false. Bar chart of the top value counts as an inline SVG string.

Numeric columns

Present for columns whose dtype is numeric (integer or float), or duration (timedelta). Boolean columns have a subset of these keys (only mean).

Key	Type	Description
n_unique	integer	Number of distinct values.
unique_proportion	number	Fraction of distinct values relative to n_rows.
is_high_cardinality	boolean	true when n_unique exceeds cardinality_threshold.
mean	number	Arithmetic mean of non-null values.
standard_deviation	number	Standard deviation of non-null values. null when it cannot be computed (e.g. single non-null value).
inter_quartile_range	number	Difference between the 75th and 25th percentiles.
quantiles	object	Map of quantile level (as a numeric key) to value, for levels 0.0, 0.25, 0.5, 0.75, and 1.0. Absent when value_is_constant is true.
constant_value	number	Optional. Present only when value_is_constant is true. The single value shared by all non-null rows.
is_duration	boolean	true for timedelta / duration columns (values were converted to a numeric unit before statistics were computed).
duration_unit	string or null	Unit used when is_duration is true: one of "microsecond", "millisecond", "second", "hour", "day", or "year". null for non-duration columns.
histogram_data	histogram data object	Bin counts and edges for the distribution histogram. Always present for non-constant numeric columns (even when plots_skipped is true).
histogram_plot	string (SVG)	Optional. Present only when plots_skipped is false and order_by is not set. Distribution histogram as an inline SVG string.
line_plot	string (SVG)	Optional. Present only when plots_skipped is false and order_by is set. Line chart of the column values against the sort column as an inline SVG string.

Datetime columns

Present for columns with a date or datetime dtype.

Key	Type	Description
n_unique	integer	Number of distinct values.
unique_proportion	number	Fraction of distinct values relative to n_rows.
is_high_cardinality	boolean	true when n_unique exceeds cardinality_threshold.
min	string (ISO 8601)	Earliest datetime value. Absent when value_is_constant is true.
max	string (ISO 8601)	Latest datetime value. Absent when value_is_constant is true.
constant_value	string (ISO 8601)	Optional. Present only when value_is_constant is true. The single datetime value shared by all non-null rows.
histogram_data	histogram data object	Bin counts and edges. Always present for non-constant datetime columns (even when plots_skipped is true).
histogram_plot	string (SVG)	Optional. Present only when plots_skipped is false and value_is_constant is false. Distribution histogram as an inline SVG string.

Histogram data object

The histogram_data key on numeric and datetime column objects contains an object with the following keys.

Key	Type	Description
bin_counts	array of integers	Count of values in each bin (length n).
bin_edges	array of numbers	Left and right edges of each bin (length n + 1). Refer to numpy.histogram() for more detail.
n_low_outliers	integer	Number of values below the plotted range that were excluded from the histogram bins.
n_high_outliers	integer	Number of values above the plotted range that were excluded from the histogram bins.
total_seconds_offset	number	Only present for datetime columns. Offset value subtracted from all values before building the histogram. The offset is the minimum of the column.

Association object

Each entry in the top-level top_associations array describes the association between a pair of columns.

Key	Type	Description
left_column_name	string	Name of the first column in the pair.
left_column_idx	integer	Zero-based index of the first column in the pair.
right_column_name	string	Name of the second column in the pair.
right_column_idx	integer	Zero-based index of the second column in the pair.
cramer_v	number or null	Cramér’s V statistic ([0, 1]) for the pair. null when it could not be computed.
pearson_corr	number or null	Pearson correlation coefficient ([-1, 1]) for the pair. null when it could not be computed (e.g. one column is not numeric).