creating mesh data from xyz data

Community matplotlib-users
1

Hi list,

I have some files with data stored in columns:

x1 y1 z1
x2 y2 z2
x3 y3 z3
x4 y4 z4
x5 y5 z5
.......

and I need to make a contour plot of this data using matplotlib. The
problem is that contour plot functions usually handle a different kind
of input:

X=[[x1,x2,x3,x4,x5,x6],
[x1,x2,x3,x4,x5,x6],
[x1,x2,x3,x4,x5,x6],...

Y=[[y1,y1,y1,y1,y1,y1],
[y2,y2,y2,y2,y2,y2],
[y3,y3,y3,y3,y3,y3],.....

Z=[[z1,z2,z3,z4,z5,z6],
[z7,z8,zz9,z10,z11,z12],....

I usually load data using 3 lists: x, y and z; I wonder if there is
any function which is able to take these 3 lists and return the right
input for matplotlib functions.

cheers

g

2

Hi list,

I have some files with data stored in columns:

x1 y1 z1
x2 y2 z2
x3 y3 z3
x4 y4 z4
x5 y5 z5
.......

and I need to make a contour plot of this data using matplotlib. The
problem is that contour plot functions usually handle a different kind
of input:

X=[[x1,x2,x3,x4,x5,x6],
[x1,x2,x3,x4,x5,x6],
[x1,x2,x3,x4,x5,x6],...

Y=[[y1,y1,y1,y1,y1,y1],
[y2,y2,y2,y2,y2,y2],
[y3,y3,y3,y3,y3,y3],.....

Z=[[z1,z2,z3,z4,z5,z6],
[z7,z8,zz9,z10,z11,z12],....

I usually load data using 3 lists: x, y and z; I wonder if there is
any function which is able to take these 3 lists and return the right
input for matplotlib functions.

cheers

giuseppe

3

Hi Giuseppe

you can load your datafile with pylab... see my little function which
i'm using

import pylab as pl

def readXY(filename):

   x,y,z = pl.load(filename, unpack=True)
   return x,y,z

(X, Y, Z) = readXY("datafile.dat")

after that you have your values in the arrays X;Y;Z

kind regards

Giuseppe Aprea wrote:

···

Hi list,

I have some files with data stored in columns:

x1 y1 z1
x2 y2 z2
x3 y3 z3
x4 y4 z4
x5 y5 z5
.......

and I need to make a contour plot of this data using matplotlib. The
problem is that contour plot functions usually handle a different kind
of input:

X=[[x1,x2,x3,x4,x5,x6],
[x1,x2,x3,x4,x5,x6],
[x1,x2,x3,x4,x5,x6],...

Y=[[y1,y1,y1,y1,y1,y1],
[y2,y2,y2,y2,y2,y2],
[y3,y3,y3,y3,y3,y3],.....

Z=[[z1,z2,z3,z4,z5,z6],
[z7,z8,zz9,z10,z11,z12],....

I usually load data using 3 lists: x, y and z; I wonder if there is
any function which is able to take these 3 lists and return the right
input for matplotlib functions.

cheers

giuseppe

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4

Hi Giuseppe,

As far as I understand you are looking for numpy.meshgrid, e.g.

# grid in x- direction
x = np.linspace(0, 1, 10)
# grid in y-direction
y = np.arange(5)
# generate 2D-vectors out of x and y
x, y = np.meshgrid(x, y)
print np.shape(x)
print np.shape(y)

Furthermore you have to reshape your z-data accordingly, e.g.

z = np.reshape(z, np.shape(x))

or transposed ... this depends on the storage of your data

kind regards Matthias

···

On Wednesday 09 September 2009 12:02:31 Giuseppe Aprea wrote:

Hi list,

I have some files with data stored in columns:

x1 y1 z1
x2 y2 z2
x3 y3 z3
x4 y4 z4
x5 y5 z5
.......

and I need to make a contour plot of this data using matplotlib. The
problem is that contour plot functions usually handle a different kind
of input:

X=[[x1,x2,x3,x4,x5,x6],
[x1,x2,x3,x4,x5,x6],
[x1,x2,x3,x4,x5,x6],...

Y=[[y1,y1,y1,y1,y1,y1],
[y2,y2,y2,y2,y2,y2],
[y3,y3,y3,y3,y3,y3],.....

Z=[[z1,z2,z3,z4,z5,z6],
[z7,z8,zz9,z10,z11,z12],....

I usually load data using 3 lists: x, y and z; I wonder if there is
any function which is able to take these 3 lists and return the right
input for matplotlib functions.

cheers

giuseppe