units.c

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/*!
   \file lib/gis/units.c
 
   \brief GIS Library - Units management and conversion
 
   (C) 2001-2010 by the GRASS Development Team
 
   This program is free software under the GNU General Public License
   (>=v2). Read the file COPYING that comes with GRASS for details.
 
   \author Original author CERL
   \author Adopted for libgis by Martin Landa <landa.martin gmail.com> (2010)
   \author Temporal units and unit type check from Soeren gebbert <soerengebbert
   googlemail.com> (2012)
 */
 
#include <string.h>
 
#include <grass/gis.h>
#include <grass/glocale.h>
 
/*!
   \brief Units conversion from meters to units
 
   Units codes (gis.h):
   - U_METERS
   - U_KILOMETERS
   - U_MILES
   - U_FEET
   - U_USFEET
 
   Returns a factor which converts meters to units (by multiplication).
 
   \param units units code
 
   \return factor
 */
double G_meters_to_units_factor(int units)
{
    switch (units) {
    case U_METERS:
        return 1.0;
        break;
 
    case U_KILOMETERS:
        return 1.0e-3;
        break;
 
    case U_MILES:
        return 6.21371192237334e-4; /*  1 / (0.0254 * 12 * 5280)    */
        break;
 
    case U_FEET:
        return 3.28083989501312; /*  1 / (0.0254 * 12)    */
        break;
 
    case U_USFEET:
        return 3.28083333333333; /*  1 / (1200/3937)    */
        break;
 
    default:
        return 1.0;
        break;
    }
 
    return 1.0;
}
 
/*!
   \brief Units conversion from square meters to square units
 
   Units codes (gis.h):
   - U_METERS
   - U_KILOMETERS
   - U_ACRES
   - U_HECTARES
   - U_MILES
   - U_FEET
   - U_USFEET
 
   Returns a factor which converts square meters to square units (by
   multiplication).
 
   \param units units code
 
   \return factor
 */
double G_meters_to_units_factor_sq(int units)
{
    switch (units) {
    case U_METERS:
        return 1.0;
        break;
 
    case U_KILOMETERS:
        return 1.0e-6;
        break;
 
    case U_ACRES:
        return 2.47105381467165e-4; /* 640 acres in a sq mile */
        break;
 
    case U_HECTARES:
        return 1.0e-4;
        break;
 
    case U_MILES:
        return 3.86102158542446e-7; /*  1 / (0.0254 * 12 * 5280)^2  */
        break;
 
    case U_FEET:
        return 10.7639104167097; /*  1 / (0.0254 * 12)^2  */
        break;
 
    case U_USFEET:
        return 10.7638673611111; /*  1 / (1200/3937)^2    */
        break;
 
    default:
        return 1.0;
        break;
    }
 
    return 1.0;
}
 
/** \brief Check if the unit is of spatial type
 
  \param units units code from gis.h
 
  \return 1 if True, 0 otherwise
 */
 
int G_is_units_type_spatial(int units)
{
    switch (units) {
    case U_METERS:
        return 1;
    case U_KILOMETERS:
        return 1;
    case U_HECTARES:
        return 1;
    case U_ACRES:
        return 1;
    case U_MILES:
        return 1;
    case U_FEET:
        return 1;
    case U_USFEET:
        return 1;
    case U_RADIANS:
        return 1;
    case U_DEGREES:
        return 1;
    }
    return 0;
}
 
/** \brief Check if the unit is of temporal type
 
  \param units units code from gis.h
 
  \return 1 if True, 0 otherwise
 */
 
int G_is_units_type_temporal(int units)
{
    switch (units) {
    case U_YEARS:
        return 1;
    case U_MONTHS:
        return 1;
    case U_DAYS:
        return 1;
    case U_HOURS:
        return 1;
    case U_MINUTES:
        return 1;
    case U_SECONDS:
        return 1;
    }
    return 0;
}
 
/*!
   \brief Get localized units name
 
   Units codes (gis.h):
   - U_METERS
   - U_KILOMETERS
   - U_ACRES
   - U_HECTARES
   - U_MILES
   - U_FEET
   - U_USFEET
 
   \param units units code
   \param plural plural form if true
   \param square area units if true
 
   \return units name
   \return NULL if units not found
 */
const char *G_get_units_name(int units, int plural, int square)
{
    switch (units) {
    case U_UNKNOWN:
        if (square)
            return plural ? _("square units") : _("square unit");
        else
            return plural ? _("units") : _("unit");
        break;
 
    case U_METERS:
        if (square)
            return plural ? _("square meters") : _("square meter");
        else
            return plural ? _("meters") : _("meter");
        break;
 
    case U_KILOMETERS:
        if (square)
            return plural ? _("square kilometers") : _("square kilometer");
        else
            return plural ? _("kilometers") : _("kilometer");
        break;
 
    case U_ACRES:
        if (square)
            return plural ? _("acres") : _("acre");
        else
            return G_get_units_name(G_units(G_database_unit_name(1)), plural,
                                    square);
        break;
 
    case U_HECTARES:
        if (square)
            return plural ? _("hectares") : _("hectare");
        else
            return G_get_units_name(G_units(G_database_unit_name(1)), plural,
                                    square);
        break;
 
    case U_MILES:
        if (square)
            return plural ? _("square miles") : _("square mile");
        else
            return plural ? _("miles") : _("mile");
        break;
 
    case U_FEET:
        if (square)
            return plural ? _("square feet") : _("square foot");
        else
            return plural ? _("feet") : _("foot");
        break;
 
    case U_USFEET:
        if (square)
            return plural ? _("square US feet") : _("square US foot");
        else
            return plural ? _("US feet") : _("US foot");
        break;
 
    case U_DEGREES:
        if (square)
            return plural ? _("square degrees") : _("square degree");
        else
            return plural ? _("degrees") : _("degree");
        break;
 
    case U_YEARS:
        return plural ? _("years") : _("year");
        break;
 
    case U_MONTHS:
        return plural ? _("months") : _("month");
        break;
 
    case U_DAYS:
        return plural ? _("days") : _("day");
        break;
 
    case U_HOURS:
        return plural ? _("hours") : _("hour");
        break;
 
    case U_MINUTES:
        return plural ? _("minutes") : _("minute");
        break;
 
    case U_SECONDS:
        return plural ? _("seconds") : _("second");
        break;
    }
 
    return NULL;
}
 
/*!
   \brief Get units code by name
 
   Units codes (gis.h):
   - U_METERS
   - U_KILOMETERS
   - U_ACRES
   - U_HECTARES
   - U_MILES
   - U_FEET
   - U_USFEET
   - ...
   - U_YEARS
   - ...
 
   \param units_name units name (singular or plural form)
 
   \return units code
   \return U_UNKNOWN if not found
 */
int G_units(const char *units_name)
{
    if (units_name == NULL) {
        return G_units(G_database_unit_name(1));
    }
 
    if (strcasecmp(units_name, "meter") == 0 ||
        strcasecmp(units_name, "meters") == 0)
        return U_METERS;
    else if (strcasecmp(units_name, "kilometer") == 0 ||
             strcasecmp(units_name, "kilometers") == 0)
        return U_KILOMETERS;
    else if (strcasecmp(units_name, "acre") == 0 ||
             strcasecmp(units_name, "acres") == 0)
        return U_ACRES;
    else if (strcasecmp(units_name, "hectare") == 0 ||
             strcasecmp(units_name, "hectares") == 0)
        return U_HECTARES;
    else if (strcasecmp(units_name, "mile") == 0 ||
             strcasecmp(units_name, "miles") == 0)
        return U_MILES;
    else if (strcasecmp(units_name, "foot") == 0 ||
             strcasecmp(units_name, "feet") == 0)
        return U_FEET;
    else if (strcasecmp(units_name, "foot_us") == 0 ||
             strcasecmp(units_name, "foot_uss") == 0)
        return U_USFEET;
    else if (strcasecmp(units_name, "degree") == 0 ||
             strcasecmp(units_name, "degrees") == 0)
        return U_DEGREES;
    else if (strcasecmp(units_name, "year") == 0 ||
             strcasecmp(units_name, "years") == 0)
        return U_YEARS;
    else if (strcasecmp(units_name, "month") == 0 ||
             strcasecmp(units_name, "months") == 0)
        return U_MONTHS;
    else if (strcasecmp(units_name, "day") == 0 ||
             strcasecmp(units_name, "days") == 0)
        return U_DAYS;
    else if (strcasecmp(units_name, "hour") == 0 ||
             strcasecmp(units_name, "hours") == 0)
        return U_HOURS;
    else if (strcasecmp(units_name, "minute") == 0 ||
             strcasecmp(units_name, "minutes") == 0)
        return U_MINUTES;
    else if (strcasecmp(units_name, "second") == 0 ||
             strcasecmp(units_name, "seconds") == 0)
        return U_SECONDS;
 
    return U_UNKNOWN;
}