watex.datasets.gdata.make_erp(*, n_stations=42, max_rho=1000.0, min_rho=1.0, step=20.0, reflong='110:29:09.00', reflat='26:03:05.00', utm_zone='29N', order='+', full_coordinates=True, raise_warning=False, as_frame=False, seed=None, is_utm=False, epsg=None, **coord_kws)

Generate Electrical Resistivity Profiling (ERP) data from stations and coordinates points.

To generate samples from specific area, it is better to provide both latitude and longitude values from a single station of this area as arguments passed to parameters reflat and reflong respectively. Also specify the utm_zone for the lat/lon coordinates conversion into UTM if necessary. If not useful, can turn off the parameter full_coordinates to False.

Parameters:

• n_stations (int, default=42) – number of measurements stations

• max_rho (float, default=1e3) – maximum resistivity value on the survey area in \(\Omega.m\)

• min_rho (float, default=1e0) – minimum resistivity value on the survey area in \(\Omega.m\)

• reflong (float or string or list of [start, stop], default='110:29:09.00') – Reference longitude in degree decimal or in DD:MM:SS for the first station considered as the origin of the landmark.

• reflat (float or string or list of [start, stop], default='26:03:05.00') – Reference latitude in degree decimal or in DD:MM:SS for the reference site considered as the landmark origin. If value is given in a list, it can contain the start point and the stop point.

• step (float or str , default=20) – Offset or the distance of seperation between different sites in meters. If the value is given as string type, except the km, it should be considered as a m value. Only meters and kilometers are accepables.

• order (str , default='-') – Direction of the projection line. By default the projected line is in ascending order i.e. from SW to NE with angle r set to 45 degrees. Could be - for descending order. Any other value should be in ascending order.

• utm_zone (string (##N or ##S), default='29N') – utm zone in the form of number and North or South hemisphere, 10S or 03N Must be given if utm2deg is set to True.

• full_coordinates (bool, default=True,) – Convert latitude and longitude to approximate UTM values. Easting and northing are gotten using the reference ellipsoid =23 with WGS84. If False, easting and northing are not computed and set to null.

• raise_warning (bool, default=True,) – Raises warnings if GDAL is not set or the coordinates accurately status.

• as_frame (bool, default=False,) – if True, outputs the data into as a pandas dataframe, Boxspace object otherwise.

• seed (int, Optional,) – It allows reproducing the same data. If value is passed, it reproduces the same data at that sample points.

• is_utm (bool, default=False) –

  Type of coordinates passed to reflat and reflong` params for generating longitude-latitude coordinates. If is_utm is explicity set to True, that means values reflong and reflat arein UTM coordinates. Then the conversion to longitude-latitude should be operated. However if is_utm is False when reflat and reflong values are greater than 90 and 180 degrees respectively, an errors should raise.

  New in version 0.2.1.

• epsg (int, str, Optional) – EPSG number defining projection. See http://spatialreference.org/ref/ for moreinfo. Overrides utm_zone if both are provided

• coord_kws (dict,) – Additional keywords passed to makeCoords().

Return type:

(pd.Dataframe | Boxspace )

Examples

>>> from watex.datasets.gdata import make_erp
>>> erp_data = make_erp (n_stations =50 , step =30  , as_frame =True)
>>> erp_data.head(3)
Out[256]:
   station  longitude  latitude        easting    northing  resistivity
0        0 -13.488511  0.000997  668210.580864  110.183287   225.265306
1       30 -13.488511  0.000997  668210.581109  110.183482   327.204082
2       60 -13.488510  0.000997  668210.581355  110.183676   204.877551

watex.datasets.gdata.make_ves(*, samples=31, min_rho=10.0, max_rho=1000.0, max_depth=100.0, order='-', as_frame=False, seed=None, iorder=3, xy=None, is_utm=False, add_xy=False, utm_zone=None, epsg=None)

Generate Vertical Electrical Sounding (VES) data from pseudo-depth measurements.

For a large pseudo-depth measurements, one can change the number of samples to a large values. The default samples presumed collected is samples=31 measurements in deeper.

Parameters:

• samples (int, default=42) – number of measurements depth AB/2 in meters.

• max_rho (float, default=1e3) – maximum resistivity value expected in deeeper on the survey area in \(\\Omega.m\)

• min_rho (float, default=1e1) – minimum resistivity value expected in deeper on the survey area in \(\\Omega.m\)

• order (str , default='-') – Direction of the projection line. By default the projected line is in ascending order i.e. from SW to NE with angle r set to 45 degrees. Could be - for descending order. Any other value should be in ascending order.

• max_depth (float, default=100) – Value of the measurement in deeper expected to reach by AB/2 in meters.

• as_frame (bool, default=False,) – if True, outputs the data into as a pandas dataframe, Boxspace object otherwise.

• seed (int, Optional,) – It allows reproducing the same data. If value is passed, it reproduces the same data at that sample points.

• iorder (int, default=3) – Inflexion order. It is a positive value greater than 0. If None, it should be computed using the length of extrema (local + global). It also might be lower as possible to let the fitting VES curve more realistic.

• xy (tuple, optional) –

  Coordinates point ( easting, northing ) or (lon, lat) corresponding to the VES points sves. If coordinates values are not given coordinates are randomly generated into (lon, lat) and stored into the attribute xy. To returns the xy auto-coordinates when as_frame=True set add_xy to True.

  New in version 0.2.1.

• is_utm (bool, default=False) – In principle, xy expects to be in longitude-latitude coordinates. However if coordinates are passed into a UTM such as easting-northing, user can specify the utm_zone to convert the xy values into a valid longitude and latitude coordinates.

• add_xy (bool, default=False) – Add xy coordinates to the VES dataframe.

• utm_zone (str, Optional) – To generate coordinates xy from a specific zone, utm_zone can be specified, otherwise 29N is used instead.

• epsg (int, str, Optional) – EPSG number defining projection. See http://spatialreference.org/ref/ for moreinfo. Overrides utm_zone if both are provided

Return type:

(pd.Dataframe | Boxspace )

Notes

when returning the Boxspace object, each columns of ‘VES’ data can be retrieved as an attributes. Check the examples below

Examples

>>> from watex.datasets.gdata import make_ves
>>> b = make_ves (samples =50 , order ='+') # 50 measurements in deeper
>>> b.resistivity [:-7]
Out[314]:
array([429.873 , 434.255 , 438.5707, 442.8203, 447.0042, 451.1228,
       457.5775])
>>> b.frame.head(3)
Out[315]:
    AB   MN  resistivity
0  1.0  0.6   429.872999
1  2.0  0.6   434.255018
2  3.0  0.6   438.570675
>>> ves_data = make_ves (samples =50 , min_rho =10, max_rho =1e5 ,
                         as_frame =True, add_xy= True ,
                         xy = ( 3143965.855 , 336704.455) ,
                         is_utm = True , utm_zone = '49N', epsg =None)
>>> ves_data.head(2)
Out[316]:
    AB   MN   resistivity   longitude   latitude
0  1.0  0.6  51544.426685  107.901553 -61.802165
1  2.0  0.6  51420.739513  107.901553 -61.802165