View source for Tutorial:DataMelt/3 Data Containers


= 1D arrays =

1D arrays in DataMelt are designed for numerical calculations and are optimized for 
numbers. We first consider <javadoc>jhplot/P0D.html|P0D</javadoc>  arrays (to hold double values) and <javadoc>jhplot/P0I.html|P0I</javadoc> (to hold integer values)

<jc lang="dmelt">
from jhplot import P0D
p0=P0D("test")
for i in range(10):
      p0.add(i)
print p0.toString()
</jc>

One can view the data containers using several methods. One is '''toString()''' which converts data into a string. One can write data into a file (including a compression) using the method '''toFile(file)'''. One can also view data in a sortable table using the method '''toTable()''':

<jc lang="dmelt">
from jhplot  import P0D
p0=P0D("test")
for i in range(1,50,2):
      p0.add(i)
p0.toTable()
</jc>

As for any DataMelt data object, one can write and read arrays into files using the method "toFile" and read
using the method "read()"

<jcode lang="python">
p0.toFile("data.txt")
</jcode>

and read it back as:

<jcode lang="python">
p0.read("data.txt")
</jcode>

If a file was zipped use the method "readZip()". 

One can access various statistical characteristics of the P0D arrays as:

<jc dmelt member_edit>
from jhplot  import P0D
p0=P0D("test")
for i in range(1,50,2):
      p0.add(i)
print p0.getStatString()
</jc>
<fc #008000>Exercise: try to increase the number of iteration to 1000 and see the output.
</jnote>


<ifauth ns="learn">

== jhplot classes ==


*   <javadoc>jhplot/P0D.html|jhplot.P0D</javadoc> - double values
*   <javadoc>jhplot/P0I.html|jhplot.P0I</javadoc> - integer values
*   <javadoc>jhplot/math/DoubleArray.html|jhplot.math.DoubleArray</javadoc> - double X-Y values
*   <javadoc>jhplot/math/IntegerArray.html|jhplot.math.IntegerArray</javadoc> - integer X-Y values



== colt classes ==


*   <javadoc>cern/colt/list/DoubleArrayList.html|cern.colt.list.DoubleArrayList</javadoc> - double values
*   <javadoc>cern/colt/list/FloatArrayList.html|cern.colt.list.FloatArrayList</javadoc> - float values
*   <javadoc>cern/colt/list/IntArrayList.html|cern.colt.list.IntArrayList</javadoc> - integer values
*   <javadoc>cern/colt/list/ShortArrayList.html|cern.colt.list.ShortArrayList</javadoc> - short values
*   <javadoc>cern/colt/list/ChartArrayList.html|cern.colt.list.ChartArrayList</javadoc> - chart values
*   <javadoc>cern/colt/list/BooleanArrayList.html|cern.colt.list.BooleanArrayList</javadoc> - boolean values

</ifauth>

= 2D arrays =


2D arrays are based on the Java class <javadoc>jhplot/P1D.html|  P1D</javadoc>. This class can be used to show data in X-Y plane
As before, one can fill such arrays using the method "add(x,y)". 

Here is a simple example how to show several data sets on on X-Y graph:
<jc lang="dmelt">
from jhplot  import  P1D, HPlot
from java.awt import Color

p1=P1D("1st data set")
p1.add(1,2); p1.add(2,3); p1.add(4,5)

p2=P1D("2nd data set")
p2.add(-1,3); p2.add(5,-2); p2.add(1,0)
p2.setColor(Color.red)

c1 = HPlot("Canvas")
c1.visible()
c1.setAutoRange()
c1.draw(p1); c1.draw(p2)
</jc>

<ifauth ns="learn">

== jhplot classes ==
[[/dmelt/api/jhplot/P1D.html|jhplot.P1D</javadoc> - double X-Y values (errors optionally)
[[/dmelt/api/jhplot/math/DoubleArray.html|jhplot.math.DoubleArray</javadoc> - double X-Y values
[[/dmelt/api/jhplot/math/IntegerArray.html|jhplot.math.IntegerArray</javadoc> - integer X-Y values

</ifauth>

= N-dimensional arrays =

<ifauth ns="learn">

== jhplot classes ==

*<javadoc>jhplot/PND.html|jhplot.PND</javadoc> - double array in N dimensions
*<javadoc>jhplot/PND.html|jhplot.PNI</javadoc> - integer array in N dimensions