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What is the Most Efficient Way of Printing A Dict's Contents Out In Columns?

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  What is the Most Efficient Way of Printing A Dict's Contents Out In Columns? Zachary Dziura <zcdziura@gmail.com> - 2011-06-14 08:29 -0700
    Re: What is the Most Efficient Way of Printing A Dict's Contents Out In Columns? Terry Reedy <tjreedy@udel.edu> - 2011-06-14 12:06 -0400
      Re: What is the Most Efficient Way of Printing A Dict's Contents Out In Columns? Zach Dziura <zcdziura@gmail.com> - 2011-06-14 10:48 -0700
        Re: What is the Most Efficient Way of Printing A Dict's Contents Out In Columns? MRAB <python@mrabarnett.plus.com> - 2011-06-14 19:37 +0100
        Re: What is the Most Efficient Way of Printing A Dict's Contents Out In Columns? Terry Reedy <tjreedy@udel.edu> - 2011-06-15 00:53 -0400
    Re: What is the Most Efficient Way of Printing A Dict's Contents Out In Columns? Karim <karim.liateni@free.fr> - 2011-06-14 20:28 +0200
    Re: What is the Most Efficient Way of Printing A Dict's Contents Out In Columns? Ben Finney <ben+python@benfinney.id.au> - 2011-06-15 09:40 +1000
      Re: What is the Most Efficient Way of Printing A Dict's Contents Out In Columns? Chris Angelico <rosuav@gmail.com> - 2011-06-15 10:08 +1000

#7615 — What is the Most Efficient Way of Printing A Dict's Contents Out In Columns?

I have a dict that I would like to print out in a series of columns,
rather than as a bunch of lines. Normally when you do print(dict), the
output will look something like this:

{'Header2': ['2', '5', '8'], 'Header3': ['3', '6', '9'], 'Header1':
['1', '4', '7'], 'Header4': ['10', '11', '12']}

I can then iterate through (in this case) a list of the headers in
order to produce something similar to this:

Header1 = ['1', '4', '7']
Header2 = ['2', '5', '8']
Header3 = ['3', '6', '9']
Header4 = ['10', '11', '12']

What I want to know is how I can print out that information in a
column, where the header is the first line of the column, with the
data following underneath, like so:

Header1        Header2        Header3        Header4
1                  2                  3                   4
5                  6                  7                   8
9                  10                11                 12

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#7618

On 6/14/2011 11:29 AM, Zachary Dziura wrote:
> I have a dict that I would like to print out in a series of columns,
> rather than as a bunch of lines. Normally when you do print(dict), the
> output will look something like this:
>
> {'Header2': ['2', '5', '8'], 'Header3': ['3', '6', '9'], 'Header1':
> ['1', '4', '7'], 'Header4': ['10', '11', '12']}
>
> I can then iterate through (in this case) a list of the headers in
> order to produce something similar to this:
>
> Header1 = ['1', '4', '7']
> Header2 = ['2', '5', '8']
> Header3 = ['3', '6', '9']
> Header4 = ['10', '11', '12']
>
> What I want to know is how I can print out that information in a
> column, where the header is the first line of the column, with the
> data following underneath, like so:
>
> Header1        Header2        Header3        Header4
> 1                  2                  3                   4
> 5                  6                  7                   8
> 9                  10                11                 12

You did not specify how much can be assumed about the dict and built in 
to the program and how much needs to be discovered with code. Assuming 
that this is not homework, here is a start:

d={'Header2': ['2', '5', '8'], 'Header3': ['3', '6', '9'],
    'Header1': ['1', '4', '7'], 'Header4': ['10', '11', '12']}

arr = []
for key,value in d.items():
     line = ['{:>10s}'.format(key)]
     for num in value:
         line.append('{:>10s}'.format(num))
     arr.append(line)

for line in zip(*arr):
     for item in line:
         print(item, end='')
     print() # newline
 >>>
    Header2   Header3   Header1   Header4
          2         3         1        10
          5         6         4        11
          8         9         7        12

For zip(*arr) to work properly, each line of arr should have the same 
length, which means that either each value of d has the same length or 
that you find the max length and pad lines with blanks up to the max 
length. The code above assumes the first.

If the items in each value of d are not strings, more fiddling is 
needed. The printed field size is also arbitrary. It needs adjusting for 
the actual max length. You might want to adjust it for each key-value 
pair in the dict, which is to say, each column of the resulting table.

-- 
Terry Jan Reedy

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#7622

> d={'Header2': ['2', '5', '8'], 'Header3': ['3', '6', '9'],
>     'Header1': ['1', '4', '7'], 'Header4': ['10', '11', '12']}
>
> arr = []
> for key,value in d.items():
>      line = ['{:>10s}'.format(key)]
>      for num in value:
>          line.append('{:>10s}'.format(num))
>      arr.append(line)
>
> for line in zip(*arr):
>      for item in line:
>          print(item, end='')
>      print() # newline
>  >>>
>     Header2   Header3   Header1   Header4
>           2         3         1        10
>           5         6         4        11
>           8         9         7        12
>
> For zip(*arr) to work properly, each line of arr should have the same
> length, which means that either each value of d has the same length or
> that you find the max length and pad lines with blanks up to the max
> length. The code above assumes the first.
>
> If the items in each value of d are not strings, more fiddling is
> needed. The printed field size is also arbitrary. It needs adjusting for
> the actual max length. You might want to adjust it for each key-value
> pair in the dict, which is to say, each column of the resulting table.
>
> --
> Terry Jan Reedy

I just have one quick question. On the line where you have zip(*arr),
what is the * for? Is it like the pointer operator, such as with C? Or
is it exactly the pointer operator?

Otherwise, thank you for the example! This isn't homework, but I'm
working on something at work, and I was wondering how to properly
format the output from CSV files into another file. It's all a part of
an analyzer script for database tables, and the table wherein. Thank
you a bunch for the help!

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#7627

On 14/06/2011 18:48, Zach Dziura wrote:
[snip]
> I just have one quick question. On the line where you have zip(*arr),
> what is the * for? Is it like the pointer operator, such as with C? Or
> is it exactly the pointer operator?
>
[snip]
The * in the argument list of a function call unpacks the following
list as arguments for the call, for example, zip(*[0, 1, 2]) becomes
zip(0, 1, 2), so zip(*arr) becomes zip(arr[0], arr[1], ...).

There's also **, which unpacks a dict as keyword arguments.

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#7672

On 6/14/2011 2:37 PM, MRAB wrote:
> On 14/06/2011 18:48, Zach Dziura wrote:
> [snip]
>> I just have one quick question. On the line where you have zip(*arr),
>> what is the * for? Is it like the pointer operator, such as with C? Or
>> is it exactly the pointer operator?
>>
> [snip]
> The * in the argument list of a function call unpacks the following
> list as arguments for the call, for example, zip(*[0, 1, 2]) becomes
> zip(0, 1, 2), so zip(*arr) becomes zip(arr[0], arr[1], ...).
>
> There's also **, which unpacks a dict as keyword arguments.

* and ** in a function call, which distribute arguments,
are essentially the inverse of * and ** in function definitions,
where they say to collect arguments.

-- 
Terry Jan Reedy

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#7625

On 06/14/2011 05:29 PM, Zachary Dziura wrote:
> I have a dict that I would like to print out in a series of columns,
> rather than as a bunch of lines. Normally when you do print(dict), the
> output will look something like this:
>
> {'Header2': ['2', '5', '8'], 'Header3': ['3', '6', '9'], 'Header1':
> ['1', '4', '7'], 'Header4': ['10', '11', '12']}
>
> I can then iterate through (in this case) a list of the headers in
> order to produce something similar to this:
>
> Header1 = ['1', '4', '7']
> Header2 = ['2', '5', '8']
> Header3 = ['3', '6', '9']
> Header4 = ['10', '11', '12']
>
> What I want to know is how I can print out that information in a
> column, where the header is the first line of the column, with the
> data following underneath, like so:
>
> Header1        Header2        Header3        Header4
> 1                  2                  3                   4
> 5                  6                  7                   8
> 9                  10                11                 12
Over alternative that only costs 2 lines of code, use pretty print (not 
in columns but crystal clear):

import pprint
pprint.pprint(my_dict)

or in a file:
pprint.pprint(my_dict, open("output.dat", "wb"))

Cheers
karim

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#7645

Zachary Dziura <zcdziura@gmail.com> writes:

> What I want to know is how I can print out that information in a
> column, where the header is the first line of the column, with the
> data following underneath, like so:

I'm glad you got some good replies. It probably reflects badly on me
that my first thought was <URL:http://bash.org/?5804>.

-- 
 \      “In case of fire, do your utmost to alarm the porter.” —hotel, |
  `\                                                            Vienna |
_o__)                                                                  |
Ben Finney

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#7650

On Wed, Jun 15, 2011 at 9:40 AM, Ben Finney <ben+python@benfinney.id.au> wrote:
> Zachary Dziura <zcdziura@gmail.com> writes:
>
>> What I want to know is how I can print out that information in a
>> column, where the header is the first line of the column, with the
>> data following underneath, like so:
>
> I'm glad you got some good replies. It probably reflects badly on me
> that my first thought was <URL:http://bash.org/?5804>.

Well *OBVIOUSLY* the difference is that that snippet is referring to
"Ms Access", and on this list we're working with "Montgomery Python",
and as we all know, women simply cannot do these things.

Chris Angelico
/me ducks the slings and arrows of outrageous sexism

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