---
myst:
    substitutions:
        bloc:
            python: 1,4,15-16,20
            cpp: 1-2,4,12-13
---
# Import data from a `TNtuple`/`TDSNtuple`/{{ttr}}

From a {{ttr}} object (or any of its derived-object) contained in a {{root}}-file, it is possible to 
import data, with or without selection of a variable and addition of other ones through formula then 
deletions of patterns ensuring a criterion

{{  
    "```{literalinclude} " + parent_dir 
    + "/roottest/uranie/doc/dataserver/data/" + language + "/draw_hsimple_scatterplot." 
    + extension + "\n"
    + ":language: " + language + "\n"
    + ":lines: " + bloc[language] + "\n"
    + "```" 
}}  

**Description of data importation of a TTree from a {{root}} file**

1. Specification of the namespace.

2. Creation of a pointer *tds* to an object of type `TDataServer` without name and title.

3. Fill the {{tds}} with all branches contained in the tree *ntuple* that is contained in 
`hsimple.root`. Two new attributes are computed on the fly and a selection is applied on the patterns 
to be kept;

4. Plots scatterplot of the variable **py** versus the variable **px**

In this case, *tds* is constructed from the `TTree` *ntuple* contained in the file `hsimple.root` 
where all initial variables are kept (__\*__ character). {numref}`fig_hsimplecontenu` shows the 
content of the *ntuple*. Two new variables are then added on top, defined by the equations "px\*py" 
and "py\*px" on both side of the "\*" string. A cut is finally done, to exclude all data that would 
satisfy the following equation $px^2 + py^2 < 2$

{{  
    "```{" "figure" "} " + parent_dir + 
        "/usermanual/dataserver/figures/hsimplecontaint.png\n"
    ":align: center\n"
    ":name: fig_hsimplecontenu\n"
    + figure_scale + "\n"
    "\n"
    'Content of the *ntuple* tree contained in "hsimple.root" file.\n'
    "```"
}}

The obtained graph is as follow:

{{  
    "```{" "figure" "} " + parent_dir + 
        "/roottest/build/uranie/doc/dataserver/data/" + language + 
        "/hsimple_scatterplot.png\n"
    ":align: center\n"
    ":name: dataserver_hsimple_scatterplot\n"
    + figure_scale + "\n"
    "\n"
    'Data importation from a TNtuple\n'
    "```"
}}

```{admonition} Summary: Loading data ( TNtupleD of {{root}} in a TFile)
- `ntupleDataRead` (__const char \*__ file, __const char \*__ tree, __const char \*__ svar="\*", 
__const char \*__ cut="")

    Loads the data contained in the `TNtupleD tree` of file {{root}} `TFile file` by selecting/creating 
    the list of variables `svar` (the variables are separated by the ":" character, and "\*" character 
    means recalling all variables of the TNtupleD) and by deleting all patterns ensuring the criterion 
    `cut`.
```