Text in tkinter refuses to left justify

May 6, 2024

I have some code that outputs some mass spec data statistics, e.g.

    r43_header_label = tk.Label(stats_frame, text='4/3 Ratio')
    r43_header_label.config(font=('System', 20, 'bold'))
    r43_header_label.pack()
    if analysis.ratio43_t0int > 0.01:
        r43_t0int_label  = tk.Label(stats_frame, text=f'  t₀: {analysis.ratio43_t0int:.3f} ± {analysis.ratio43_uncert:.3e}', anchor='w', justify='left')
    else:
        r43_t0int_label  = tk.Label(stats_frame, text=f'  t₀: {analysis.ratio43_t0int:.3e} ± {analysis.ratio43_uncert:.3e}', anchor='w', justify='left')
    r43_t0int_label.pack()
    r43_t0err_label  = tk.Label(stats_frame, text=f'  error: {analysis.ratio43_puncert:.3f}%', anchor='w', justify='left')
    r43_t0err_label.pack()

I thought surely between anchoring the text to 'w'est and using justify='left' would convince tkinter that I want the text to be left justified, however, here is an example of the results, which are clearly centered.

Besides the fact that the +/- error is vastly lower than the % error, (I’m working on that too), what am I doing wrong?

Even better, how could I have the text be left justified and the numbers all start in a neat row, e.g.

t0:       0.75
error:    2.356%
mean:     1.5

>Solution :

Appropriately setting the fill option for each label’s pack call should cause them to align properly

r43_header_label.pack(fill='x')
...
r43_t0int_label.pack(fill='x')
...
r43_t0err_label.pack(fill='x')

If you want two columns for your data wherein each row has a name label and an associated value, an easy if naïve approach is to encapsulate two labels in a Frame and pack them accordingly