def Pc(CASRN, AvailableMethods=False, Method=None, IgnoreMethods=[SURF]):
def list_methods():<EOL><INDENT>methods = []<EOL>if CASRN in _crit_IUPAC.index and not np.isnan(_crit_IUPAC.at[CASRN, '<STR_LIT>']):<EOL><INDENT>methods.append(IUPAC)<EOL><DEDENT>if CASRN in _crit_Matthews.index and not np.isnan(_crit_Matthews.at[CASRN, '<STR_LIT>']):<EOL><INDENT>methods.append(MATTHEWS)<EOL><DEDENT>if CASRN in _crit_CRC.index and not np.isnan(_crit_CRC.at[CASRN, '<STR_LIT>']):<EOL><INDENT>methods.append(CRC)<EOL><DEDENT>if CASRN in _crit_PSRKR4.index and not np.isnan(_crit_PSRKR4.at[CASRN, '<STR_LIT>']):<EOL><INDENT>methods.append(PSRK)<EOL><DEDENT>if CASRN in _crit_PassutDanner.index and not np.isnan(_crit_PassutDanner.at[CASRN, '<STR_LIT>']):<EOL><INDENT>methods.append(PD)<EOL><DEDENT>if CASRN in _crit_Yaws.index and not np.isnan(_crit_Yaws.at[CASRN, '<STR_LIT>']):<EOL><INDENT>methods.append(YAWS)<EOL><DEDENT>if CASRN:<EOL><INDENT>methods.append(SURF)<EOL><DEDENT>if IgnoreMethods:<EOL><INDENT>for Method in IgnoreMethods:<EOL><INDENT>if Method in methods:<EOL><INDENT>methods.remove(Method)<EOL><DEDENT><DEDENT><DEDENT>methods.append(NONE)<EOL>return methods<EOL><DEDENT>if AvailableMethods:<EOL><INDENT>return list_methods()<EOL><DEDENT>if not Method:<EOL><INDENT>Method = list_methods()[<NUM_LIT:0>]<EOL><DEDENT>if Method == IUPAC:<EOL><INDENT>_Pc = float(_crit_IUPAC.at[CASRN, '<STR_LIT>'])<EOL><DEDENT>elif Method == MATTHEWS:<EOL><INDENT>_Pc = float(_crit_Matthews.at[CASRN, '<STR_LIT>'])<EOL><DEDENT>elif Method == CRC:<EOL><INDENT>_Pc = float(_crit_CRC.at[CASRN, '<STR_LIT>'])<EOL><DEDENT>elif Method == PSRK:<EOL><INDENT>_Pc = float(_crit_PSRKR4.at[CASRN, '<STR_LIT>'])<EOL><DEDENT>elif Method == PD:<EOL><INDENT>_Pc = float(_crit_PassutDanner.at[CASRN, '<STR_LIT>'])<EOL><DEDENT>elif Method == YAWS:<EOL><INDENT>_Pc = float(_crit_Yaws.at[CASRN, '<STR_LIT>'])<EOL><DEDENT>elif Method == SURF:<EOL><INDENT>_Pc = third_property(CASRN=CASRN, P=True)<EOL><DEDENT>elif Method == NONE:<EOL><INDENT>return None<EOL><DEDENT>else:<EOL><INDENT>raise Exception('<STR_LIT>')<EOL><DEDENT>return _Pc<EOL>
r'''This function handles the retrieval of a chemical's critical
    pressure. Lookup is based on CASRNs. Will automatically select a data
    source to use if no Method is provided; returns None if the data is not
    available.

    Prefered sources are 'IUPAC' for organic chemicals, and 'MATTHEWS' for 
    inorganic chemicals. Function has data for approximately 1000 chemicals.

    Examples
    --------
    >>> Pc(CASRN='64-17-5')
    6137000.0

    Parameters
    ----------
    CASRN : string
        CASRN [-]

    Returns
    -------
    Pc : float
        Critical pressure, [Pa]
    methods : list, only returned if AvailableMethods == True
        List of methods which can be used to obtain Pc with the given inputs

    Other Parameters
    ----------------
    Method : string, optional
        The method name to use. Accepted methods are 'IUPAC', 'MATTHEWS', 
        'CRC', 'PSRK', 'PD', 'YAWS', and 'SURF'. All valid values are also held  
        in the list `Pc_methods`.
    AvailableMethods : bool, optional
        If True, function will determine which methods can be used to obtain
        Pc for the desired chemical, and will return methods instead of Pc
    IgnoreMethods : list, optional
        A list of methods to ignore in obtaining the full list of methods,
        useful for for performance reasons and ignoring inaccurate methods

    Notes
    -----
    A total of seven sources are available for this function. They are:

        * 'IUPAC', a series of critically evaluated
          experimental datum for organic compounds in [1]_, [2]_, [3]_, [4]_,
          [5]_, [6]_, [7]_, [8]_, [9]_, [10]_, [11]_, and [12]_.
        * 'MATTHEWS', a series of critically
          evaluated data for inorganic compounds in [13]_.
        * 'CRC', a compillation of critically
          evaluated data by the TRC as published in [14]_.
        * 'PSRK', a compillation of experimental and
          estimated data published in [15]_.
        * 'PD', an older compillation of
          data published in [16]_
        * 'YAWS', a large compillation of data from a
          variety of sources; no data points are sourced in the work of [17]_.
        * SURF', an estimation method using a
          simple quadratic method for estimating Pc from Tc and Vc. This is
          ignored and not returned as a method by default.

    References
    ----------
    .. [1] Ambrose, Douglas, and Colin L. Young. "Vapor-Liquid Critical
       Properties of Elements and Compounds. 1. An Introductory Survey."
       Journal of Chemical & Engineering Data 41, no. 1 (January 1, 1996):
       154-154. doi:10.1021/je950378q.
    .. [2] Ambrose, Douglas, and Constantine Tsonopoulos. "Vapor-Liquid
       Critical Properties of Elements and Compounds. 2. Normal Alkanes."
       Journal of Chemical & Engineering Data 40, no. 3 (May 1, 1995): 531-46.
       doi:10.1021/je00019a001.
    .. [3] Tsonopoulos, Constantine, and Douglas Ambrose. "Vapor-Liquid
       Critical Properties of Elements and Compounds. 3. Aromatic
       Hydrocarbons." Journal of Chemical & Engineering Data 40, no. 3
       (May 1, 1995): 547-58. doi:10.1021/je00019a002.
    .. [4] Gude, Michael, and Amyn S. Teja. "Vapor-Liquid Critical Properties
       of Elements and Compounds. 4. Aliphatic Alkanols." Journal of Chemical
       & Engineering Data 40, no. 5 (September 1, 1995): 1025-36.
       doi:10.1021/je00021a001.
    .. [5] Daubert, Thomas E. "Vapor-Liquid Critical Properties of Elements
       and Compounds. 5. Branched Alkanes and Cycloalkanes." Journal of
       Chemical & Engineering Data 41, no. 3 (January 1, 1996): 365-72.
       doi:10.1021/je9501548.
    .. [6] Tsonopoulos, Constantine, and Douglas Ambrose. "Vapor-Liquid
       Critical Properties of Elements and Compounds. 6. Unsaturated Aliphatic
       Hydrocarbons." Journal of Chemical & Engineering Data 41, no. 4
       (January 1, 1996): 645-56. doi:10.1021/je9501999.
    .. [7] Kudchadker, Arvind P., Douglas Ambrose, and Constantine Tsonopoulos.
       "Vapor-Liquid Critical Properties of Elements and Compounds. 7. Oxygen
       Compounds Other Than Alkanols and Cycloalkanols." Journal of Chemical &
       Engineering Data 46, no. 3 (May 1, 2001): 457-79. doi:10.1021/je0001680.
    .. [8] Tsonopoulos, Constantine, and Douglas Ambrose. "Vapor-Liquid
       Critical Properties of Elements and Compounds. 8. Organic Sulfur,
       Silicon, and Tin Compounds (C + H + S, Si, and Sn)." Journal of Chemical
       & Engineering Data 46, no. 3 (May 1, 2001): 480-85.
       doi:10.1021/je000210r.
    .. [9] Marsh, Kenneth N., Colin L. Young, David W. Morton, Douglas Ambrose,
       and Constantine Tsonopoulos. "Vapor-Liquid Critical Properties of
       Elements and Compounds. 9. Organic Compounds Containing Nitrogen."
       Journal of Chemical & Engineering Data 51, no. 2 (March 1, 2006):
       305-14. doi:10.1021/je050221q.
    .. [10] Marsh, Kenneth N., Alan Abramson, Douglas Ambrose, David W. Morton,
       Eugene Nikitin, Constantine Tsonopoulos, and Colin L. Young.
       "Vapor-Liquid Critical Properties of Elements and Compounds. 10. Organic
       Compounds Containing Halogens." Journal of Chemical & Engineering Data
       52, no. 5 (September 1, 2007): 1509-38. doi:10.1021/je700336g.
    .. [11] Ambrose, Douglas, Constantine Tsonopoulos, and Eugene D. Nikitin.
       "Vapor-Liquid Critical Properties of Elements and Compounds. 11. Organic
       Compounds Containing B + O; Halogens + N, + O, + O + S, + S, + Si;
       N + O; and O + S, + Si." Journal of Chemical & Engineering Data 54,
       no. 3 (March 12, 2009): 669-89. doi:10.1021/je800580z.
    .. [12] Ambrose, Douglas, Constantine Tsonopoulos, Eugene D. Nikitin, David
       W. Morton, and Kenneth N. Marsh. "Vapor-Liquid Critical Properties of
       Elements and Compounds. 12. Review of Recent Data for Hydrocarbons and
       Non-Hydrocarbons." Journal of Chemical & Engineering Data, October 5,
       2015, 151005081500002. doi:10.1021/acs.jced.5b00571.
    .. [13] Mathews, Joseph F. "Critical Constants of Inorganic Substances."
       Chemical Reviews 72, no. 1 (February 1, 1972): 71-100.
       doi:10.1021/cr60275a004.
    .. [14] Haynes, W.M., Thomas J. Bruno, and David R. Lide. CRC Handbook of
       Chemistry and Physics, 95E. Boca Raton, FL: CRC press, 2014.
    .. [15] Horstmann, Sven, Anna Jabłoniec, Jörg Krafczyk, Kai Fischer, and
       Jürgen Gmehling. "PSRK Group Contribution Equation of State:
       Comprehensive Revision and Extension IV, Including Critical Constants
       and Α-Function Parameters for 1000 Components." Fluid Phase Equilibria
       227, no. 2 (January 25, 2005): 157-64. doi:10.1016/j.fluid.2004.11.002.
    .. [16] Passut, Charles A., and Ronald P. Danner. "Acentric Factor. A
       Valuable Correlating Parameter for the Properties of Hydrocarbons."
       Industrial & Engineering Chemistry Process Design and Development 12,
       no. 3 (July 1, 1973): 365–68. doi:10.1021/i260047a026.
    .. [17] Yaws, Carl L. Thermophysical Properties of Chemicals and
       Hydrocarbons, Second Edition. Amsterdam Boston: Gulf Professional
       Publishing, 2014.