Pretty-printing a table in Python
Often you'll have a table of data. You want to print it out as text, but aligned for readability. Here is a simple module to do that. I'll discuss the code below.
First, we have format_num. This basically just adds commas to our numbers (we want it to be pretty, right?).
locale.setlocale(locale.LC_NUMERIC, "")
def format_num(num):
"""Format a number according to given places.
Adds commas, etc. Will truncate floats into ints!"""
try:
inum = int(num)
return locale.format("%.*f", (0, inum), True)
except (ValueError, TypeError):
return str(num)
Next, get_max_width gives us the maximum width of a given column in the table. We'll use this when we decide how much to pad each column.
"""Get the maximum width of the given column index"""
return max([len(format_num(row[index])) for row in table])
Finally, the money function. Note that I pass in the output stream — this makes the function more versatile (we could print to a file, StringIO(), stdout, etc.). It also makes it easier to unit test. We could have done this behind the scenes by redirecting sys.stdout, but that would be unpythonic! <G>
"""Prints out a table of data, padded for alignment
@param out: Output stream (file-like object)
@param table: The table to print. A list of lists.
Each row must have the same number of columns. """
col_paddings = []
for i in range(len(table[0])):
col_paddings.append(get_max_width(table, i))
for row in table:
# left col
print >> out, row[0].ljust(col_paddings[0] + 1),
# rest of the cols
for i in range(1, len(row)):
col = format_num(row[i]).rjust(col_paddings[i] + 2)
print >> out, col,
print >> out
And we top it off with a bit of test code.
table = [["", "taste", "land speed", "life"],
["spam", 300101, 4, 1003],
["eggs", 105, 13, 42],
["lumberjacks", 13, 105, 10]]
import sys
out = sys.stdout
pprint_table(out, table)
The output:
taste land speed life
spam 300,101 4 1,003
eggs 105 13 42
lumberjacks 13 105 10
The linked zip file has unit tests that exercise the code a bit more thoroughly.
Hello,
I work in a Federal University, and here we implements a huge system for 1.300.000 students of public schools.
I see you module, and add it to one of my programs. But theres something that I can’t change. I want to align the text inside the table at left. Actualy its align on the right.
Can you help me on this?
Thanks a lot
Vinicius
Sorry,
Just solve it.
Thanks a lot
Very nice module
Hi Vinicius — glad to hear you solved your problem. I guess it would make the code more flexible to enable configuration of the justification style.
Yeah, its possible. I just change one caracter to get the expected out.
Thanks again
i used your module and the result looked very nice. Thanks a lot.
Duke
Another thing (and maybe Python has a module that does this) is to print pretty tables:
+—————————————-+
| | taste | land speed | life |
+—————————————-+
| data | | | |
| data | | | |
| data | | | |
+—————————————-+
@Robert
There’s a recipe on activestate.com that does this.
Or try the texttable package from PyPI:
http://pypi.python.org/pypi?name=texttable&:action=display
Hi, Here’s a minor update for python 3.2.
+ Uses character “|” to delineate the table lines.
- Removes number formatting.
def pprintTable(out, table): """Prints out a table of data, padded for alignment @param out: Output stream (file-like object) @param table: The table to print. A list of lists. Each row must have the same number of columns. """ def format(num): """Format a number according to given places. Adds commas, etc. Will truncate floats into ints!""" #try: # inum = int(num) # return locale.format("%.*f", (0, inum), True) #except (ValueError, TypeError): return str(num) def get_max_width(table1, index1): """Get the maximum width of the given column index""" return max([len(format(row1[index1])) for row1 in table1]) col_paddings = [] for i in range(len(table[0])): col_paddings.append(get_max_width(table, i)) for row in table: # left col print(row[0].ljust(col_paddings[0] + 1),end="||",file=out) # rest of the cols for i in range(1, len(row)): col = format(row[i]).rjust(col_paddings[i] + 1) print(col,end=" |",file=out) print(file=out) returnExample use:
doh!
This forum software removed my formatting and indentation!
my post merely a minor re-write, anyway.
@J_Tom_Moon_79
Thanks for the code! I edited your comment to wrap the code in pre tags rather than code tags. I need to update the css file so that multiline code looks nice.
Ryan,
What should I do to use float values on the table? I’ve been working at that for a while and can’t figure it out…