Matplotlib Table- Assign different text alignments to different columns

Question

I am creating a two column table and want the text to be as close as possible. How can I specify that the first column be right aligned and the second be left aligned?

I’ve tried by setting the general cellloc to one side (cellloc sets the text alignment)

from matplotlib import pyplot as plt

data = [['x','x'] for x in range(10)]
bbox = [0,0,1,1]

tb = plt.table(cellText = data, cellLoc='right', bbox = bbox)
plt.axis('off') # get rid of chart axis to only show table

Then looping through cells in the second columns to set them to left align:

for key, cell in tb.get_celld().items():
    if key[1] == 1: # if the y value is equal to 1, meaning the second column
        cell._text.set_horizontalalignment('left') # then change the alignment

This loop immediately above has no effect, and the text remains right aligned.

Am I missing something? Or is this not possible?

EDIT

A workaround is for me to separate the data into two different lists, one for each column. This produces the results I’m looking for, but I’d like to know if anyone knows of another way.

data_col1 = [xy[0] for xy in data]
data_col2 = [xy[1] for xy in data] 

tb = plt.table(cellText = data_col2, rowLabels=data_col1, cellLoc='left', rowLoc='right', bbox = bbox)

Asked By: jma

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Source

Answer 1

Instead of setting the alignment of the text itself, you need to set the position of the text inside the table cell. This is determined by the cell’s ._loc attribute.

def set_align_for_column(table, col, align="left"):
    cells = [key for key in table._cells if key[1] == col]
    for cell in cells:
        table._cells[cell]._loc = align

Some complete example:

from matplotlib import pyplot as plt

data = [['x','x'] for x in range(10)]
bbox = [0,0,1,1]

tb = plt.table(cellText = data, cellLoc='right', bbox = bbox)
plt.axis('off') # get rid of chart axis to only show table

def set_align_for_column(table, col, align="left"):
    cells = [key for key in table._cells if key[1] == col]
    for cell in cells:
        table._cells[cell]._loc = align

set_align_for_column(tb, col=0, align="right")
set_align_for_column(tb, col=1, align="left")

plt.show()

(The approach used here is similar to changing the cell padding as in this question: Matplotlib Text Alignment in Table)

Answered By: ImportanceOfBeingErnest

Answer 2

Another possible solution would be to use the method get_celld() of your table which returns a dictionary of matplotlib.table.CustomCell objects which you can then loop through and change in a similar way that @ImportanceOfBeingErnest’s answer does:

from matplotlib import pyplot as plt

data = [['x','x'] for x in range(10)]
bbox = [0,0,1,1]

tb = plt.table(cellText = data, cellLoc='right', bbox = bbox)
plt.axis('off')

cells = tb.get_celld()

for i in range(0, len(data)):
    cells[i, 1]._loc = 'left'   # 0 is first column, 1 is second column

plt.show()

Which will give the same result.

Answered By: DavidG

Answer 3

3000 views and 4 years later, things might have changed a bit.
In matplotlib 3.3.3 (tested) 3.6 (docs) accessing the cells is much simpler than the code above, as the table can be addressed as a list directly:

cell = table[row_number,column_number]

Also the function _text.set_horizontalalignment(‘left’) which is reported as not working above, now seems to work. However setting _loc sets _loc but seems to have no effect on the display (according to doc 3.6, it should) but it does not seem to do any harm.

My belt and braces code to setting column col to left alignment is

for i in range(0,nrows)
    tb[i, col]._loc = 'left'
    tb[i, col]._text.set_horizontalalignment('left')

Thanks to the contributors above for getting me on the right track

Answered By: Tony Tebby

Matplotlib Table- Assign different text alignments to different columns

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