Add dump_stan_json function

stanio/__init__.py

@@ -1,7 +1,14 @@
 from .csv import read_csv
-from .json import write_stan_json
+from .json import write_stan_json, dump_stan_json
 from .reshape import Variable, parse_header, stan_variables
 
-__all__ = ["read_csv", "write_stan_json", "Variable", "parse_header", "stan_variables"]
+__all__ = [
+    "read_csv",
+    "write_stan_json",
+    "dump_stan_json",
+    "Variable",
+    "parse_header",
+    "stan_variables",
+]
 
-__version__ = "0.2.0"
+__version__ = "0.3.0"

stanio/json.py

@@ -36,6 +36,25 @@ def process_value(val: Any) -> Any:
     return val
 
 
+def dump_stan_json(data: Mapping[str, Any]) -> str:
+    """
+    Convert a mapping of strings to data to a JSON string.
+
+    Values can be any numeric type, a boolean (converted to int),
+    or any collection compatible with :func:`numpy.asarray`, e.g a
+    :class:`pandas.Series`.
+
+    Produces a string compatible with the
+    `Json Format for Cmdstan
+    <https://mc-stan.org/docs/cmdstan-guide/json.html>`__
+
+    :param data: A mapping from strings to values. This can be a dictionary
+        or something more exotic like an :class:`xarray.Dataset`. This will be
+        copied before type conversion, not modified
+    """
+    return json.dumps(process_dictionary(data))
+
+
 def write_stan_json(path: str, data: Mapping[str, Any]) -> None:
     """
     Dump a mapping of strings to data to a JSON file.

test/test_json.py

@@ -8,7 +8,7 @@
 import pandas as pd
 import pytest
 
-from stanio.json import write_stan_json
+from stanio.json import dump_stan_json, write_stan_json
 
 
 @pytest.fixture(scope="module")
@@ -163,3 +163,11 @@ def test_tuples(TMPDIR) -> None:
     file_tuple = os.path.join(TMPDIR, "tuple.json")
     write_stan_json(file_tuple, dict_tuples)
     compare_before_after(file_tuple, dict_tuples, dict_tuple_exp)
+
+
+def test_write_vs_dump(TMPDIR):
+    dict_list = {"a": [1.0, 2.0, 3.0]}
+    file_write = os.path.join(TMPDIR, "write.json")
+    write_stan_json(file_write, dict_list)
+    with open(file_write) as fd:
+        assert fd.read() == dump_stan_json(dict_list)