(use_cases_howto_py_tds_array_py)=
# Macro **"howtoConvertTDataServerArray.py"**

## Objective

The goal of this macro is only to show how to convert a `TDataServer` into a `numpy.array` and vice-versa.

## Macro {{uranie}}

{{
    "```{literalinclude} " + parent_dir +
        "/roottest/uranie/doc/overview/use_cases/python/howtoConvertTDataServerArray.py\n"
    + ":language: python\n"
    + ":lines: 1-5,11-40\n"
    + "```"
}}

The first block reads an input file `myData.dat` and store the data in the {{tds}} as usually done. 
The new block is what we recommend: define the list of variable that one wants to store


{{
    "```{literalinclude} " + parent_dir +
        "/roottest/uranie/doc/overview/use_cases/python/howtoConvertTDataServerArray.py\n"
    + ":language: python\n"
    + ":lines: 19\n"
    + "```"
}}
            
Once done, the `np.array` has to be constructed by defining its content and size. Thanks to the 
{{tds}} object and the list of variable this can be done easily as


{{
    "```{literalinclude} " + parent_dir +
        "/roottest/uranie/doc/overview/use_cases/python/howtoConvertTDataServerArray.py\n"
    + ":language: python\n"
    + ":lines: 22-23\n"
    + "```"
}}

Finally, the `extractData` method is called with the given created array and list of variables.


{{
    "```{literalinclude} " + parent_dir +
        "/roottest/uranie/doc/overview/use_cases/python/howtoConvertTDataServerArray.py\n"
    + ":language: python\n"
    + ":lines: 25\n"
    + "```"
}}

The second part consists in creating a brand new {{tds}} from a `np.array`, which basically will 
consist in our case in re-creatting the original {{tds}} with a different name and title. To do so, 
one starts by creating the {{tds}}


{{
    "```{literalinclude} " + parent_dir +
        "/roottest/uranie/doc/overview/use_cases/python/howtoConvertTDataServerArray.py\n"
    + ":language: python\n"
    + ":lines: 32\n"
    + "```"
}}

Then, one loops over the list of variable and in the loop two things are done :

- a new array is created by transposing the data, selecting the proper array of data and construct 
this as an memory-continuous array (for C++-consistency)

- a new attribute is created using the method `addAttributeUsingData` that needs the name of the 
attribute, the buffer and the size of the array provded

{{
    "```{literalinclude} " + parent_dir +
        "/roottest/uranie/doc/overview/use_cases/python/howtoConvertTDataServerArray.py\n"
    + ":language: python\n"
    + ":lines: 34-37\n"
    + "```"
}}

The output of this macro is shown in [](#use_cases_howto_py_tds_array_py_console).

(use_cases_howto_py_tds_array_py_console)=
## Console


{{
    "```{literalinclude} " + parent_dir +
        "/roottest/build/uranie/doc/overview/use_cases/python/howtoConvertTDataServerArray_clean.log\n"
    + ":language: none\n"
    + ":lines: 2-34,36-51\n"
    + "```"
}}