Search code examples
pythonstringlistcenter

How to realize a table with a specific elements subset

I have to sketch out the periodic table with ten elements through a list like the following one:

pt = [(1,"Hydrogen","H",1), (2,"Helium","He",4), ...].

As follows, the widths of the corresponding columns in the table and to the required alignment

 (3 right + 20 left + 6 center + 10 right).

The final results I should obtain look like this.

enter image description here

I have tried to create through the package tabulate, following this procedure

pt = [(1,"Hydrogen","H",1.008), (2,"Helium","He",4.0026), (3, "Lithium", "Li", 6.94), (4, "Beryllium", "Be", 9.0122),
      (5, "Boron", "B", 10.81), (6, "Carbon", "C", 12.011), (7, "Nitrogen", "N", 14.007), (8, "Oxygen", "O", 15.999),
      (9, "Fluorine", "F", 18.998), (10, "Neon", "Ne", 20.180)]
head = ["No.", "Name", "Symbol", "Weight"]
print(tabulate(pt, headers=head, tablefmt="grid"))

The results is nice

enter image description here

but since I have to respect the width dimensions, as described above, I do not how to include them in the code. I was suggested to create the first three lines manually but lines with chemical elements should be created in the 'for' loop (for an item in pt:). Use methods for strings (rjust, center, ljust).

Is there anyone that knows how to do this?

Solution

  • Since you use tabulate, there is a solution to modify your code by:

    1. Adding an extra row full of characters of specified size for each column at the end the array
    2. Calling tabulate including specification of the alignment using coalign
    3. Remove the extra row

    Since the output is a string, the width of the columns is not associated with any measure e.g. in cm, so you will need to define a length scale that suits your needs, i.e. the number of characters per required width unit.

    Note that 2 characters are removed from the computed width to account for the inner column margins which are 1 character left and right.

    from tabulate import tabulate

pt = [(1,"Hydrogen","H",1.008), (2,"Helium","He",4.0026), (3, "Lithium", "Li", 6.94), (4, "Beryllium", "Be", 9.0122),
      (5, "Boron", "B", 10.81), (6, "Carbon", "C", 12.011), (7, "Nitrogen", "N", 14.007), (8, "Oxygen", "O", 15.999),
      (9, "Fluorine", "F", 18.998), (10, "Neon", "Ne", 20.180)]
head = ["No.", "Name", "Symbol", "Weight"]

lengthScale = 2
widths = [3, 20, 6, 10]
pt.append(["-"*(width*lengthScale-2) for width in widths])

tab = tabulate(pt, headers=head, tablefmt="grid", colalign=("right","left","center","right"))

for line in range(2):
    tab = tab[:tab.rfind('\n')]

print(tab)

    It produces:

    +-------+----------------------------------------+------------+--------------------+
|   No. | Name                                   |   Symbol   |             Weight |
+=======+========================================+============+====================+
|     1 | Hydrogen                               |     H      |              1.008 |
+-------+----------------------------------------+------------+--------------------+
|     2 | Helium                                 |     He     |             4.0026 |
+-------+----------------------------------------+------------+--------------------+
|     3 | Lithium                                |     Li     |               6.94 |
+-------+----------------------------------------+------------+--------------------+
|     4 | Beryllium                              |     Be     |             9.0122 |
+-------+----------------------------------------+------------+--------------------+
|     5 | Boron                                  |     B      |              10.81 |
+-------+----------------------------------------+------------+--------------------+
|     6 | Carbon                                 |     C      |             12.011 |
+-------+----------------------------------------+------------+--------------------+
|     7 | Nitrogen                               |     N      |             14.007 |
+-------+----------------------------------------+------------+--------------------+
|     8 | Oxygen                                 |     O      |             15.999 |
+-------+----------------------------------------+------------+--------------------+
|     9 | Fluorine                               |     F      |             18.998 |
+-------+----------------------------------------+------------+--------------------+
|    10 | Neon                                   |     Ne     |              20.18 |
+-------+----------------------------------------+------------+--------------------+