Difference between revisions of "Data Manipulation Functions"

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for i = 1:length(w)
 
for i = 1:length(w)
<nowiki>  wout(i) = flip(w(i))</nowiki>
+
<nowiki>  wout(i) = flip(w(i))</nowiki>
 
end
 
end

Revision as of 16:51, 17 March 2008

Data manipulation functions change the data in some way, such as scaling or flipping it. The functions available are

>> wnew = shift(w, xshift)
>> wwout = shift_x(ww, xshift)
>> wwout = shift_y(ww, yshift)
>> wwout = shift_xy(ww, xshift, yshift)
>> wout = scale(w, factor)
>> wwout = scale_x(ww, factor)
>> wwout = scale_y(ww, factor)
>> wout = flip(w)
>> wwout = flip_x(ww)
>> wwout = flip_y(ww)

Shift Functions

These functions add a value to one of the independent variable arrays (x or y), leaving any related data (such as the signal data) untouched. For instance if an x array, [10, 20, 30, 40, 50], is shifted by 2 the output x array will be [12, 22, 32, 42, 52].

>> shift_x(ww, xshift)
>> shift_y(ww,yshift)
>> shift_xy(ww,xshift,yshift)
>> shift(w, xshift)


Example:


>> wout = shift_x(ww, 4)


Every x value in wout will have 4 added to them


Scale Functions

Multiplies one of the independent variable arrays (x or y) by a constant. For instance if an x array, [10, 20, 30, 40, 50], is scaled by 2 the output x array will be [20, 40, 60, 80, 100].

>> wwout = scale_x(w, xscale)
>> wwout = scale_y(ww, yscale)
>> wwout = scale(ww, xyscale)
  • Input is an IXT_dataset_2d object
  • Output is an IXT_dataset_2d object
  • Scales x by factor xscale
  • Scales y by factor yscale
  • Scales both x and y by amount xyscale


>> wout = scale(w, xscale)


Example:


>> wwout = scale_y(ww, 4)


will multiply every y value in wwout by 4

Flip Functions

All data, including associated signal and error data is reversed in the order it appears in the dataset. For instance if a dataset has x data [1, 2, 3, 4], signal data [34, 35, 36, 37] and error data [0.1 0.2 0.1 0.1] then the flipped data will have xdata [4, 3, 2, 1], signal data [37, 36, 35, 34] and error data [0.1 0.1 0.2 0.1].


>> flip_x(ww)

Reverses the order of x columns in IXTdataset_2d


>> flip_y(ww)

Reverses the order of y rows in IXTdatset_2d

>> flip(ww)
>> flip(w)

Reverses the order of x rows in IXTdataset_1d or both x columns and y rows in IXTdataset_2d.

Arrays of Datasets

If an array of dataset objects is passed to the function, then the operation is performed on each dataset in turn.


Example:


>> wout = flip(w)


is equivilent to


for i = 1:length(w) wout(i) = flip(w(i)) end