Question

I am creating a distance matrix in numpy, with an out put as such:

  ['H', 'B', 'D', 'A', 'I', 'C', 'F']
[[ 0.   2.4  6.1  3.2  5.2  3.9  7.1]
 [ 2.4  0.   4.1  1.2  3.2  1.9  5.1]
 [ 6.1  4.1  0.   3.1  6.9  2.8  5.2]
 [ 3.2  1.2  3.1  0.   4.   0.9  4.1]
 [ 5.2  3.2  6.9  4.   0.   4.7  7.9]
 [ 3.9  1.9  2.8  0.9  4.7  0.   3.8]
 [ 7.1  5.1  5.2  4.1  7.9  3.8  0. ]]

I am printing that x axis by just printing a list before I print the actual matrix, a:

print" ", names
print a

I need the axis in that order, as the list ‘names’ properly orders the variables with their value in the matrix. But how would i be able to get a similar y axis in numpy?

Answer 1

It is not so pretty, but this pretty table prints works:

import numpy as np

names=np.array(['H', 'B', 'D', 'A', 'I', 'C', 'F'])
a=np.array([[ 0.,   2.4,  6.1,  3.2,  5.2,  3.9,  7.1],
 [2.4,  0.,   4.1,  1.2,  3.2,  1.9,  5.1],
 [6.1,  4.1,  0.,   3.1,  6.9,  2.8,  5.2],
 [3.2,  1.2,  3.1,  0.,   4.,   0.9,  4.1],
 [5.2,  3.2,  6.9,  4.,   0.,   4.7,  7.9],
 [3.9,  1.9 , 2.8,  0.9,  4.7,  0.,   3.8],
 [7.1,  5.1,  5.2,  4.1,  7.9,  3.8,  0. ]])

def pptable(x_axis,y_axis,table):
    def format_field(field, fmt='{:,.2f}'):
        if type(field) is str: return field
        if type(field) is tuple: return field[1].format(field[0])
        return fmt.format(field)     

    def get_max_col_w(table, index):
        return max([len(format_field(row[index])) for row in table])         

    for i,l in enumerate(table):
        l.insert(0,y_axis[i])

    x_axis.insert(0,' ')    
    table.insert(0,x_axis)    
    col_paddings=[get_max_col_w(table, i) for i in range(len(table[0]))]
    for i,row in enumerate(table):
        # left col
        row_tab=[str(row[0]).ljust(col_paddings[0])]
        # rest of the cols
        row_tab+=[format_field(row[j]).rjust(col_paddings[j]) 
                for j in range(1,len(row))]
        print(' '.join(row_tab))         

x_axis=['x{}'.format(c) for c in names]
y_axis=['y{}'.format(c) for c in names]

pptable(x_axis,y_axis,a.tolist()) 

Prints:

     xH   xB   xD   xA   xI   xC   xF
yH 0.00 2.40 6.10 3.20 5.20 3.90 7.10
yB 2.40 0.00 4.10 1.20 3.20 1.90 5.10
yD 6.10 4.10 0.00 3.10 6.90 2.80 5.20
yA 3.20 1.20 3.10 0.00 4.00 0.90 4.10
yI 5.20 3.20 6.90 4.00 0.00 4.70 7.90
yC 3.90 1.90 2.80 0.90 4.70 0.00 3.80
yF 7.10 5.10 5.20 4.10 7.90 3.80 0.00

If you want the X and Y axis to be the same, just call it with two lists of the same labels.