Data Analysis Routines¶
These modules provide basic data analysis or data fitting functionality.
linefit¶
Fit a line to a data set with optional weights.
Returns the parameters of the model, bo, b1: Y = b0 + b1* X
author: | Nadia Dencheva |
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version: | ‘1.0 (2007-02-20)’ |
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stsci.tools.linefit.
linefit
(x, y, weights=None)¶ Parameters: - y (1D numpy array) – The data to be fitted
- x (1D numpy array) – The x values of the y array. x and y must have the same shape.
- weights (1D numpy array, must have the same shape as x and y) – weight values
Examples
>>> import numpy as N >>> from numpy.core import around >>> x = np.array([-5, -4 ,-3 ,-2 ,-1, 0, 1, 2, 3, 4, 5]) >>> y = np.array([1, 5, 4, 7, 10, 8, 9, 13, 14, 13, 18]) >>> around(linefit(x,y), decimals=5) array([9.27273, 1.43636]) >>> x = np.array([1.3,1.3,2.0,2.0,2.7,3.3,3.3,3.7,3.7,4.,4.,4.,4.7,4.7,5.,5.3,5.3,5.3,5.7,6.,6.,6.3,6.7]) >>> y = np.array([2.3,1.8,2.8,1.5,2.2,3.8,1.8,3.7,1.7,2.8,2.8,2.2,3.2,1.9,1.8,3.5,2.8,2.1,3.4,3.2,3.,3.,5.9]) >>> around(linefit(x,y), decimals=5) array([1.42564, 0.31579])
xyinterp¶
Module: | xyinterp.py |
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Interpolates y based on the given xval.
x and y are a pair of independent/dependent variable arrays that must be the same length. The x array must also be sorted. xval is a user-specified value. This routine looks up xval in the x array and uses that information to properly interpolate the value in the y array.
author: | Vicki Laidler |
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version: | ‘0.1 (2006-07-06)’ |
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stsci.tools.xyinterp.
xyinterp
(x, y, xval)¶ Purpose: Interpolates y based on the given xval. x and y are a pair of independent/dependent variable arrays that must be the same length. The x array must also be sorted. xval is a user-specified value. This routine looks up xval in the x array and uses that information to properly interpolate the value in the y array.
Notes
Use the searchsorted method on the X array to determine the bin in which xval falls; then use that information to compute the corresponding y value.
See also
numpy()
Parameters: - x (1D numpy array) – independent variable array: MUST BE SORTED
- y (1D numpy array) – dependent variable array
- xval (float) – the x value at which you want to know the value of y
Returns: y – the value of y corresponding to xval
Return type: Raises: - ValueError: – If arrays are unequal length; or x array is unsorted; or if xval falls outside the bounds of x (extrapolation is unsupported
version: 0.1 last modified 2006-07-06