Question :
I would like to print NumPy tabular array data, so that it looks nice. R and database consoles seem to demonstrate good abilities to do this. However, NumPy’s built-in printing of tabular arrays looks like garbage:
import numpy as np
dat_dtype = {
'names' : ('column_one', 'col_two', 'column_3'),
'formats' : ('i', 'd', '|S12')}
dat = np.zeros(4, dat_dtype)
dat['column_one'] = range(4)
dat['col_two'] = 10**(-np.arange(4, dtype='d') - 4)
dat['column_3'] = 'ABCD'
dat['column_3'][2] = 'long string'
print(dat)
# [(0, 0.0001, 'ABCD') (1, 1.0000000000000001e-005, 'ABCD')
# (2, 9.9999999999999995e-007, 'long string')
# (3, 9.9999999999999995e-008, 'ABCD')]
print(repr(dat))
# array([(0, 0.0001, 'ABCD'), (1, 1.0000000000000001e-005, 'ABCD'),
# (2, 9.9999999999999995e-007, 'long string'),
# (3, 9.9999999999999995e-008, 'ABCD')],
# dtype=[('column_one', '<i4'), ('col_two', '<f8'), ('column_3', '|S12')])
I would like something that looks more like what a database spits out, for example, postgres-style:
column_one | col_two | column_3
------------+---------+-------------
0 | 0.0001 | ABCD
1 | 1e-005 | long string
2 | 1e-008 | ABCD
3 | 1e-007 | ABCD
Are there any good third-party Python libraries to format nice looking ASCII tables?
I’m using Python 2.5, NumPy 1.3.0.
Answer #1:
I seem to be having good output with prettytable:
from prettytable import PrettyTable
x = PrettyTable(dat.dtype.names)
for row in dat:
x.add_row(row)
# Change some column alignments; default was 'c'
x.align['column_one'] = 'r'
x.align['col_two'] = 'r'
x.align['column_3'] = 'l'
And the output is not bad. There is even a border switch, among a few other options:
>>> print(x)
+------------+---------+-------------+
| column_one | col_two | column_3 |
+------------+---------+-------------+
| 0 | 0.0001 | ABCD |
| 1 | 1e-005 | ABCD |
| 2 | 1e-006 | long string |
| 3 | 1e-007 | ABCD |
+------------+---------+-------------+
>>> print(x.get_string(border=False))
column_one col_two column_3
0 0.0001 ABCD
1 1e-005 ABCD
2 1e-006 long string
3 1e-007 ABCD
Answer #2:
The tabulate package works nicely for Numpy arrays:
import numpy as np
from tabulate import tabulate
m = np.array([[1, 2, 3], [4, 5, 6]])
headers = ["col 1", "col 2", "col 3"]
# tabulate data
table = tabulate(m, headers, tablefmt="fancy_grid")
# output
print(table)
(Above code is Python 3; for Python 2 add from __future__ import print_function at top of script)
Output:
???????????????????????????????
? col 1 ? col 2 ? col 3 ?
???????????????????????????????
? 1 ? 2 ? 3 ?
???????????????????????????????
? 4 ? 5 ? 6 ?
???????????????????????????????
The package installs via pip:
$ pip install tabulate # (use pip3 for Python 3 on some systems)
Answer #3:
you can take advantage of array comprehension and use printf format strings:
for c1, c2, c3 in dat:
print "%2f | %8e | %s" % (c1, c2, c3)
https://en.wikipedia.org/wiki/Printf_format_string
And you can get even more customized if you go up to version 2.7
Answer #4:
You might want to check out Pandas which has a lot of nice features for dealing with tabular data and seems to lay things out better when printing (It is designed be a python replacement for R):
