read_dictT_read_dictReadDictReadDictread_dict (算子名称)

名称

read_dictT_read_dictReadDictReadDictread_dict — Read a dictionary from a file.

参数签名

描述

read_dictread_dictReadDictReadDictReadDictread_dict reads a dictionary from the file FileNameFileNameFileNameFileNamefileNamefile_name and returns the handle of the dictionary in DictHandleDictHandleDictHandleDictHandledictHandledict_handle.

The operator supports the following file formats:

'hdict'"hdict""hdict""hdict""hdict""hdict":

Binary HALCON format for dictionaries. Files with this format can be written by write_dictwrite_dictWriteDictWriteDictWriteDictwrite_dict. The default file extension for this format is 'hdict'.

'json'"json""json""json""json""json":

JSON (JavaScript Object Notation) file format. The default file extension for this format is 'json'.

If the given file does not exist, the operator attempts to find the file by appending the default file extensions to the filename. The file type is automatically recognized based on the file content and the file ending (which have to be consistent).

A set of additional optional parameters can be set. The names and values of the parameters are passed in GenParamNameGenParamNameGenParamNameGenParamNamegenParamNamegen_param_name and GenParamValueGenParamValueGenParamValueGenParamValuegenParamValuegen_param_value, respectively. Some of the optional parameters can only be set for a certain file type. The following values for GenParamNameGenParamNameGenParamNameGenParamNamegenParamNamegen_param_name are possible:

'json_value_true'"json_value_true""json_value_true""json_value_true""json_value_true""json_value_true", 'json_value_false'"json_value_false""json_value_false""json_value_false""json_value_false""json_value_false", 'json_value_null'"json_value_null""json_value_null""json_value_null""json_value_null""json_value_null":

Set the values that are used for JSON primitives. Valid JSON primitives are 'true'"true""true""true""true""true", 'false'"false""false""false""false""false", and 'null'"null""null""null""null""null". When encountering such a primitive in a JSON file, the corresponding value in the read dictionary is set to the value defined with these parameters. The value passed in GenParamValueGenParamValueGenParamValueGenParamValuegenParamValuegen_param_value must be a tuple of length 1.

The default values for primitives are 1 for 'true'"true""true""true""true""true", 0 for 'false'"false""false""false""false""false", and 'HNULL'"HNULL""HNULL""HNULL""HNULL""HNULL" for 'null'"null""null""null""null""null". These parameters only have an effect when reading a JSON file.

'convert_json_arrays_to'"convert_json_arrays_to""convert_json_arrays_to""convert_json_arrays_to""convert_json_arrays_to""convert_json_arrays_to":

This parameter controls which HALCON-internal data type is used to represent JSON arrays. Possible values for GenParamValueGenParamValueGenParamValueGenParamValuegenParamValuegen_param_value are:

'dict'"dict""dict""dict""dict""dict" (default):

JSON arrays are converted into HALCON-Dictionaries with consecutive integer keys starting at 0. This is always possible, even if the JSON array contains further JSON arrays. However, using dictionaries might require more memory than storing the same data in HALCON tuples.

'tuple'"tuple""tuple""tuple""tuple""tuple":

JSON arrays are converted into HALCON tuples. If this is not possible, for example if an array contains an array, an exception is raised.

'tuple_if_possible'"tuple_if_possible""tuple_if_possible""tuple_if_possible""tuple_if_possible""tuple_if_possible":

JSON arrays are converted into HALCON tuples if possible, and into HALCON dictionaries otherwise.

Note that when using this option, the structure of the returned dictionary can change even if the JSON data follows the same schema. For example, an array of 2D point coordinates of the form '{"pt": [[1,2], [3,4]]}'"{"pt": [[1,2], [3,4]]}""{"pt": [[1,2], [3,4]]}""{"pt": [[1,2], [3,4]]}""{"pt": [[1,2], [3,4]]}""{"pt": [[1,2], [3,4]]}" would be converted into an outer dictionary which contains two tuples. However, if under the same schema no points are contained in the array, the corresponding entry in the JSON of the form '{"pt": []}'"{"pt": []}""{"pt": []}""{"pt": []}""{"pt": []}""{"pt": []}" would be converted into a tuple instead of a dictionary. Code using the read dictionary must be prepared to deal with this kind of change in types.

运行信息

• Multithreading type: independent (runs in parallel even with exclusive operators).
• Multithreading scope: global (may be called from any thread).
• Processed without parallelization.

This operator returns a handle. Note that the state of an instance of this handle type may be changed by specific operators even though the handle is used as an input parameter by those operators.

参数表

结果

If the parameters are valid, the operator read_dictread_dictReadDictReadDictReadDictread_dict returns the value 2 ( H_MSG_TRUE) . If necessary an exception is raised.

可能的前置算子

write_dictwrite_dictWriteDictWriteDictWriteDictwrite_dict

可替代算子

json_to_dictjson_to_dictJsonToDictJsonToDictJsonToDictjson_to_dict, create_dictcreate_dictCreateDictCreateDictCreateDictcreate_dict

参考其它

write_dictwrite_dictWriteDictWriteDictWriteDictwrite_dict, serialize_handleserialize_handleSerializeHandleSerializeHandleSerializeHandleserialize_handle, deserialize_handledeserialize_handleDeserializeHandleDeserializeHandleDeserializeHandledeserialize_handle

模块

Foundation

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