def plot_isobar(self, P, Tmin=None, Tmax=None, methods_P=[], pts=<NUM_LIT:50>,<EOL>only_valid=True):  
if not has_matplotlib:<EOL><INDENT>raise Exception('<STR_LIT>')<EOL><DEDENT>if Tmin is None:<EOL><INDENT>if self.Tmin is not None:<EOL><INDENT>Tmin = self.Tmin<EOL><DEDENT>else:<EOL><INDENT>raise Exception('<STR_LIT>')<EOL><DEDENT><DEDENT>if Tmax is None:<EOL><INDENT>if self.Tmax is not None:<EOL><INDENT>Tmax = self.Tmax<EOL><DEDENT>else:<EOL><INDENT>raise Exception('<STR_LIT>')<EOL><DEDENT><DEDENT>if not methods_P:<EOL><INDENT>if self.user_methods_P:<EOL><INDENT>methods_P = self.user_methods_P<EOL><DEDENT>else:<EOL><INDENT>methods_P = self.all_methods_P<EOL><DEDENT><DEDENT>Ts = np.linspace(Tmin, Tmax, pts)<EOL>for method_P in methods_P:<EOL><INDENT>if only_valid:<EOL><INDENT>properties, Ts2 = [], []<EOL>for T in Ts:<EOL><INDENT>if self.test_method_validity_P(T, P, method_P):<EOL><INDENT>try:<EOL><INDENT>p = self.calculate_P(T, P, method_P)<EOL>if self.test_property_validity(p):<EOL><INDENT>properties.append(p)<EOL>Ts2.append(T)<EOL><DEDENT><DEDENT>except:<EOL><INDENT>pass<EOL><DEDENT><DEDENT><DEDENT>plt.plot(Ts2, properties, label=method_P)<EOL><DEDENT>else:<EOL><INDENT>properties = [self.calculate_P(T, P, method_P) for T in Ts]<EOL>plt.plot(Ts, properties, label=method_P)<EOL><DEDENT><DEDENT>plt.legend(loc='<STR_LIT>')<EOL>plt.ylabel(self.name + '<STR_LIT:U+002CU+0020>' + self.units)<EOL>plt.xlabel('<STR_LIT>')<EOL>plt.title(self.name + '<STR_LIT>' + self.CASRN)<EOL>plt.show()<EOL>
r'''Method to create a plot of the property vs temperature at a 
        specific pressure according to
        either a specified list of methods, or user methods (if set), or all
        methods. User-selectable number of points, and temperature range. If
        only_valid is set,`test_method_validity_P` will be used to check if 
        each condition in the specified range is valid, and
        `test_property_validity` will be used to test the answer, and the
        method is allowed to fail; only the valid points will be plotted.
        Otherwise, the result will be calculated and displayed as-is. This will
        not suceed if the method fails.

        Parameters
        ----------
        P : float
            Pressure for the isobar, [Pa]
        Tmin : float
            Minimum temperature, to begin calculating the property, [K]
        Tmax : float
            Maximum temperature, to stop calculating the property, [K]
        methods_P : list, optional
            List of methods to consider
        pts : int, optional
            A list of points to calculate the property at; if Tmin to Tmax
            covers a wide range of method validities, only a few points may end
            up calculated for a given method so this may need to be large
        only_valid : bool
            If True, only plot successful methods and calculated properties,
            and handle errors; if False, attempt calculation without any
            checking and use methods outside their bounds