String Columns

A string-column is an opaque handle wrapping a 1D column of strings. It is the string counterpart to ndarray, designed for categorical labels, names, and other non-numeric data.

String-columns use 1-based indexing (matching Maxima convention).

`df_string_column` (list) — Function

Create a string-column from a Maxima list of strings.

Each element is converted to a string via sconcat.

Examples

(%i1) sc : df_string_column(["Alice", "Bob", "Charlie"]);
(%o1)      string_column(3) ["Alice", "Bob", "Charlie"]
(%i2) df_string_column_length(sc);
(%o2)                          3
(%i3) df_string_column_ref(sc, 1);
(%o3)                        Alice

See also: df_to_string_list, df_string_column_p

`df_to_string_list` (col) — Function

Convert a string-column back to a Maxima list of strings.

Examples

(%i1) sc : df_string_column(["x", "y", "z"]);
(%o1)          string_column(3) ["x", "y", "z"]
(%i2) df_to_string_list(sc);
(%o2)                      [x, y, z]

`df_string_column_p` (x) — Function

Predicate: return true if x is a string-column handle, false otherwise.

Examples

(%i1) df_string_column_p(df_string_column(["a", "b"]));
(%o1)                         true
(%i2) df_string_column_p(42);
(%o2)                        false
(%i3) df_string_column_p(ndarray([1, 2, 3]));
(%o3)                        false

`df_string_column_ref` (col, i) — Function

Access element i (1-indexed) of a string-column.

Signals an error if i is out of bounds.

Examples

(%i1) sc : df_string_column(["red", "green", "blue"]);
(%o1)       string_column(3) ["red", "green", "blue"]
(%i2) df_string_column_ref(sc, 1);
(%o2)                          red
(%i3) df_string_column_ref(sc, 3);
(%o3)                         blue

See also: df_string_column_length, df_to_string_list

`df_string_column_length` (col) — Function

Return the number of elements in a string-column.

Examples

(%i1) df_string_column_length(df_string_column(["a", "b", "c"]));
(%o1)                          3
(%i2) df_string_column_length(df_string_column([]));
(%o2)                          0

See also: df_string_column_ref, df_table_shape

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