Pretty print 2D list?
Question:
Is there a simple, built-in way to print a 2D Python list as a 2D matrix?
So this:
[["A", "B"], ["C", "D"]]
would become something like
A B
C D
I found the pprint module, but it doesn’t seem to do what I want.
Answers:
To make things interesting, let’s try with a bigger matrix:
matrix = [
["Ah!", "We do have some Camembert", "sir"],
["It's a bit", "runny", "sir"],
["Well,", "as a matter of fact it's", "very runny, sir"],
["I think it's runnier", "than you", "like it, sir"]
]
s = [[str(e) for e in row] for row in matrix]
lens = [max(map(len, col)) for col in zip(*s)]
fmt = 't'.join('{{:{}}}'.format(x) for x in lens)
table = [fmt.format(*row) for row in s]
print 'n'.join(table)
Output:
Ah! We do have some Camembert sir
It's a bit runny sir
Well, as a matter of fact it's very runny, sir
I think it's runnier than you like it, sir
UPD: for multiline cells, something like this should work:
text = [
["Ah!", "We do havensome Camembert", "sir"],
["It's a bit", "runny", "sir"],
["Well,", "as a matternof fact it's", "very runny,nsir"],
["I think it'snrunnier", "than you", "like it,nsir"]
]
from itertools import chain, izip_longest
matrix = chain.from_iterable(
izip_longest(
*(x.splitlines() for x in y),
fillvalue='')
for y in text)
And then apply the above code.
If you can use Pandas (Python Data Analysis Library) you can pretty-print a 2D matrix by converting it to a DataFrame object:
from pandas import *
x = [["A", "B"], ["C", "D"]]
print DataFrame(x)
0 1
0 A B
1 C D
A more lightweight approach than pandas is to use the prettytable module
from prettytable import PrettyTable
x = [["A", "B"], ["C", "D"]]
p = PrettyTable()
for row in x:
p.add_row(row)
print p.get_string(header=False, border=False)
yields:
A B
C D
prettytable has lots of options to format your output in different ways.
See https://code.google.com/p/prettytable/ for more info
You can always use numpy:
import numpy as np
A = [['A', 'B'], ['C', 'D']]
print(np.matrix(A))
Output:
[['A' 'B']
['C' 'D']]
See the following code.
# Define an empty list (intended to be used as a matrix)
matrix = []
matrix.append([1, 2, 3, 4])
matrix.append([4, 6, 7, 8])
print matrix
# Now just print out the two rows separately
print matrix[0]
print matrix[1]
For Python 3 without any third part libs:
matrix = [["A", "B"], ["C", "D"]]
print('n'.join(['t'.join([str(cell) for cell in row]) for row in matrix]))
Output
A B
C D
You can update print‘s end=' ' so that it prints space instead of ‘n’ in the inner loop and outer loop can have print().
a=[["a","b"],["c","d"]]
for i in a:
for j in i:
print(j, end=' ')
print()
I found this solution from here.
Just to provide a simpler alternative to print('n'.join(['t'.join([str(cell) for cell in row]) for row in matrix])) :
matrix = [["A", "B"], ["C", "D"]]
for row in matrix:
print(*row)
Explanation
*row unpacks row, so print("A", "B") is called when row is ["A", "B"], for example.
Note
Both answers will only be formatted nicely if each column has the same width. To change the delimiter, use the sep keyword. For example,
for row in matrix:
print(*row, sep=', ')
will print
A, B
C, D
instead.
One-liner without a for loop
print(*(' '.join(row) for row in matrix), sep='n')
' '.join(row) for row in matrix) returns a string for every row, e.g. A B when row is ["A", "B"].
*(' '.join(row) for row in matrix), sep='n') unpacks the generator returning the sequence 'A B', 'C D', so that print('A B', 'C D', sep='n') is called for the example matrix given.
If you’re using a Notebook/IPython environment, then sympy can print pleasing matrices using IPython.display:
import numpy as np
from sympy import Matrix, init_printing
init_printing()
print(np.random.random((3,3)))
display(np.random.random((3,3)))
display(Matrix(np.random.random((3,3))))
I would also recommend tabulate, which can optionally print headers too:
from tabulate import tabulate
lst = [['London', 20],['Paris', 30]]
print(tabulate(lst, headers=['City', 'Temperature']))
:
City Temperature
------ -------------
London 20
Paris 30
Without any third party libraries, you could do:
matrix = [["A", "B"], ["C", "D"]]
print(*matrix, sep="n")
Output:
['A', 'B']
['C', 'D']
A simpler way is to do it using the "end" parameter in print(). This works only because in Python (and in many other languages), all letters are the same width.
table = [["A", "BC"], ["DEFG", "HIJ"]]
for row in table:
for col in row:
spaces = 5 #adjust as needed
spaces -= (len(col) - 1) #spaces everything out
print(col, end = " " * spaces)
print() #add line break before next row
The "end" function sets what will be printed after the end of the arguments, as the default is n.
As you can see, I offseted how many spaces there are according to the length of each item in each row.
Is there a simple, built-in way to print a 2D Python list as a 2D matrix?
So this:
[["A", "B"], ["C", "D"]]
would become something like
A B
C D
I found the pprint module, but it doesn’t seem to do what I want.
To make things interesting, let’s try with a bigger matrix:
matrix = [
["Ah!", "We do have some Camembert", "sir"],
["It's a bit", "runny", "sir"],
["Well,", "as a matter of fact it's", "very runny, sir"],
["I think it's runnier", "than you", "like it, sir"]
]
s = [[str(e) for e in row] for row in matrix]
lens = [max(map(len, col)) for col in zip(*s)]
fmt = 't'.join('{{:{}}}'.format(x) for x in lens)
table = [fmt.format(*row) for row in s]
print 'n'.join(table)
Output:
Ah! We do have some Camembert sir
It's a bit runny sir
Well, as a matter of fact it's very runny, sir
I think it's runnier than you like it, sir
UPD: for multiline cells, something like this should work:
text = [
["Ah!", "We do havensome Camembert", "sir"],
["It's a bit", "runny", "sir"],
["Well,", "as a matternof fact it's", "very runny,nsir"],
["I think it'snrunnier", "than you", "like it,nsir"]
]
from itertools import chain, izip_longest
matrix = chain.from_iterable(
izip_longest(
*(x.splitlines() for x in y),
fillvalue='')
for y in text)
And then apply the above code.
If you can use Pandas (Python Data Analysis Library) you can pretty-print a 2D matrix by converting it to a DataFrame object:
from pandas import *
x = [["A", "B"], ["C", "D"]]
print DataFrame(x)
0 1
0 A B
1 C D
A more lightweight approach than pandas is to use the prettytable module
from prettytable import PrettyTable
x = [["A", "B"], ["C", "D"]]
p = PrettyTable()
for row in x:
p.add_row(row)
print p.get_string(header=False, border=False)
yields:
A B
C D
prettytable has lots of options to format your output in different ways.
See https://code.google.com/p/prettytable/ for more info
You can always use numpy:
import numpy as np
A = [['A', 'B'], ['C', 'D']]
print(np.matrix(A))
Output:
[['A' 'B']
['C' 'D']]
See the following code.
# Define an empty list (intended to be used as a matrix)
matrix = []
matrix.append([1, 2, 3, 4])
matrix.append([4, 6, 7, 8])
print matrix
# Now just print out the two rows separately
print matrix[0]
print matrix[1]
For Python 3 without any third part libs:
matrix = [["A", "B"], ["C", "D"]]
print('n'.join(['t'.join([str(cell) for cell in row]) for row in matrix]))
Output
A B
C D
You can update print‘s end=' ' so that it prints space instead of ‘n’ in the inner loop and outer loop can have print().
a=[["a","b"],["c","d"]]
for i in a:
for j in i:
print(j, end=' ')
print()
I found this solution from here.
Just to provide a simpler alternative to print('n'.join(['t'.join([str(cell) for cell in row]) for row in matrix])) :
matrix = [["A", "B"], ["C", "D"]]
for row in matrix:
print(*row)
Explanation
*row unpacks row, so print("A", "B") is called when row is ["A", "B"], for example.
Note
Both answers will only be formatted nicely if each column has the same width. To change the delimiter, use the sep keyword. For example,
for row in matrix:
print(*row, sep=', ')
will print
A, B
C, D
instead.
One-liner without a for loop
print(*(' '.join(row) for row in matrix), sep='n')
' '.join(row) for row in matrix) returns a string for every row, e.g. A B when row is ["A", "B"].
*(' '.join(row) for row in matrix), sep='n') unpacks the generator returning the sequence 'A B', 'C D', so that print('A B', 'C D', sep='n') is called for the example matrix given.
If you’re using a Notebook/IPython environment, then sympy can print pleasing matrices using IPython.display:
import numpy as np
from sympy import Matrix, init_printing
init_printing()
print(np.random.random((3,3)))
display(np.random.random((3,3)))
display(Matrix(np.random.random((3,3))))
I would also recommend tabulate, which can optionally print headers too:
from tabulate import tabulate
lst = [['London', 20],['Paris', 30]]
print(tabulate(lst, headers=['City', 'Temperature']))
:
City Temperature
------ -------------
London 20
Paris 30
Without any third party libraries, you could do:
matrix = [["A", "B"], ["C", "D"]]
print(*matrix, sep="n")
Output:
['A', 'B']
['C', 'D']
A simpler way is to do it using the "end" parameter in print(). This works only because in Python (and in many other languages), all letters are the same width.
table = [["A", "BC"], ["DEFG", "HIJ"]]
for row in table:
for col in row:
spaces = 5 #adjust as needed
spaces -= (len(col) - 1) #spaces everything out
print(col, end = " " * spaces)
print() #add line break before next row
The "end" function sets what will be printed after the end of the arguments, as the default is n.
As you can see, I offseted how many spaces there are according to the length of each item in each row.