1 | #!/usr/bin/env python |
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2 | """ |
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3 | Provide I(q) = I_0 exp ( - R_g^2 q^2 / 3.0) |
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4 | Guinier function as a BaseComponent model |
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5 | """ |
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6 | |
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7 | from sans.models.BaseComponent import BaseComponent |
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8 | import math |
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9 | |
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10 | class GuinierModel(BaseComponent): |
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11 | """ |
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12 | Class that evaluates a Guinier model. |
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13 | |
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14 | I(q) = I_0 exp ( - R_g^2 q^2 / 3.0 ) |
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15 | |
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16 | List of default parameters: |
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17 | I_0 = Scale |
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18 | R_g = Radius of gyration |
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19 | |
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20 | """ |
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21 | |
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22 | def __init__(self): |
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23 | """ Initialization """ |
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24 | |
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25 | # Initialize BaseComponent first, then sphere |
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26 | BaseComponent.__init__(self) |
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27 | |
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28 | ## Name of the model |
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29 | self.name = "Guinier" |
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30 | self.description=" I(q) = I_0 exp ( - R_g^2 q^2 / 3.0 )\ |
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31 | List of default parameters:\ |
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32 | I_0 = Scale\ |
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33 | R_g = Radius of gyration" |
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34 | ## Define parameters |
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35 | self.params = {} |
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36 | self.params['scale'] = 1.0 |
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37 | self.params['rg'] = 60 |
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38 | |
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39 | ## Parameter details [units, min, max] |
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40 | self.details = {} |
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41 | self.details['scale'] = ['cm-1', None, None] |
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42 | self.details['rg'] = ['A', None, None] |
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43 | #list of parameter that cannot be fitted |
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44 | self.fixed= [] |
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45 | def _guinier(self, x): |
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46 | return self.params['scale'] * math.exp( -(self.params['rg']*x)**2 / 3.0 ) |
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47 | |
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48 | def run(self, x = 0.0): |
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49 | """ Evaluate the model |
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50 | @param x: input q-value (float or [float, float] as [r, theta]) |
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51 | @return: (guinier value) |
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52 | """ |
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53 | if x.__class__.__name__ == 'list': |
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54 | return self._guinier(x[0]) |
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55 | elif x.__class__.__name__ == 'tuple': |
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56 | raise ValueError, "Tuples are not allowed as input to BaseComponent models" |
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57 | else: |
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58 | return self._guinier(x) |
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59 | |
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60 | def runXY(self, x = 0.0): |
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61 | """ Evaluate the model |
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62 | @param x: input q-value (float or [float, float] as [qx, qy]) |
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63 | @return: guinier value |
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64 | """ |
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65 | if x.__class__.__name__ == 'list': |
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66 | q = math.sqrt(x[0]**2 + x[1]**2) |
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67 | return self._guinier(q) |
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68 | elif x.__class__.__name__ == 'tuple': |
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69 | raise ValueError, "Tuples are not allowed as input to BaseComponent models" |
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70 | else: |
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71 | return self._guinier(x) |
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