Class StringConverter

numpy/lib/_iotools.py:450–819

Factory class for function transforming a string into another object (int, float). After initialization, an instance can be called to transform a string into another object. If the string is recognized as representing a missing value, a default value is returned. Attribute

class StringConverter:
    """
    Factory class for function transforming a string into another object
    (int, float).

    After initialization, an instance can be called to transform a string
    into another object. If the string is recognized as representing a
    missing value, a default value is returned.

    Attributes
    ----------
    func : function
        Function used for the conversion.
    default : any
        Default value to return when the input corresponds to a missing
        value.
    type : type
        Type of the output.
    _status : int
        Integer representing the order of the conversion.
    _mapper : sequence of tuples
        Sequence of tuples (dtype, function, default value) to evaluate in
        order.
    _locked : bool
        Holds `locked` parameter.

    Parameters
    ----------
    dtype_or_func : {None, dtype, function}, optional
        If a `dtype`, specifies the input data type, used to define a basic
        function and a default value for missing data. For example, when
        `dtype` is float, the `func` attribute is set to `float` and the
        default value to `np.nan`.  If a function, this function is used to
        convert a string to another object. In this case, it is recommended
        to give an associated default value as input.
    default : any, optional
        Value to return by default, that is, when the string to be
        converted is flagged as missing. If not given, `StringConverter`
        tries to supply a reasonable default value.
    missing_values : {None, sequence of str}, optional
        ``None`` or sequence of strings indicating a missing value. If ``None``
        then missing values are indicated by empty entries. The default is
        ``None``.
    locked : bool, optional
        Whether the StringConverter should be locked to prevent automatic
        upgrade or not. Default is False.

    """
    _mapper = [(nx.bool_, str2bool, False),
               (nx.int_, int, -1),]

    # On 32-bit systems, we need to make sure that we explicitly include
    # nx.int64 since ns.int_ is nx.int32.
    if nx.dtype(nx.int_).itemsize < nx.dtype(nx.int64).itemsize:
        _mapper.append((nx.int64, int, -1))

    _mapper.extend([(nx.float64, float, nx.nan),
                    (nx.complex128, complex, nx.nan + 0j),