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pynxtools/dataconverter/readers/xrd/README.md

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+# XRD reader
+By XRD reader data can read from X-ray diffraction experiment and write  in a nexus (h5 type file with extension .nxs) according to NXxrd_pan application definition in NeXus, github repository (https://github.com/FAIRmat-NFDI/nexus_definitions). There are a few methods e.g. 1. θ:2θ instrument (e.g. Rigaku H3R), 2. θ:θ instrument (e.g. PANalytical X’Pert Pro). The goal with this reader to support both of that methods.
+
+**NOTE: At this moment the reader can handle file with extension `.xrdml` of version (1.5) for method-2. This reader still under development. Currently we are woking to include more file types and file versions.**
+
+## Contact persion in FAIRmat
+In principle any one from Area-B of FAIRmat consortium can be reached out, but Rubel Mozumder could be more reasonable for the early response.
+
+## Parsers
+Though, in computer science, parser is a process that reads code into smaller parts (called tocken) with relations among tockens in a tree diagram. The process helps compiler to understand the tocken relationship of the source code.
+
+Here, usully we call a program or class that reads the experimenal input file and relate the different physical/experiment concepts or propertise in a certain structure which defined by developer. The relation is a slash separated string, for example (according to xrdml file) `{/XRDmeasurement/Datapoints/position_1/axis : 2theta}`, which reads the root element or coponent is `XRDmeasurement`  with sub-element `Datapoints` with sub-element `position_1` that has a attribute or an element `axis` refering `2theta values`. In this reader, a parser that parsers a specific file type from a specific xrd method. Some of the parser features with annotated below:
+
+**NOTE: there are several parserS will be available in future.**
+
+### class pynxtools.dataconverter.readers.xrd.xrd_parser.XRDMLParser
+
+    **inputs:**
+        file_path: Full path of the input file.
+
+    **Important method:**
+        get_slash_separated_xrd_dict() -> dict
+
+        This method can be used to check if all the data from input file have been read or not, it returns the slash separated dict as described.
+
+### Other parsers
+    **Coming Soon!!**
+
+### How To
+Reader can be run from Jupyter-notebook or Jupyter-lab with the follwoing command:
+```sh
+ ! dataconverter \
+--reader xrd \
+--nxdl NXxrd_pan \
+--input-file $<xps-file location> \
+--input-file $<eln-file location> \
+--output <output-file location>.nxs
+```
+
+An example file can be found here in GitLab, but to have access in that GitLab on must need an account in https://gitlab.mpcdf.mpg.de/.