use format with tex fraction expression in matplotlib python

Solution 1:

You need to escape the curled brackets ({) with another curled bracket.

r'$\frac{{{}}}{{8}}$'.format(i)

Here the inner most bracket pair in {{{}}} is used for formatting. The escape pair {{ is replaced by a single bracket during formatting. Hence r'$\frac{{{}}}{{8}}$'.format(1) will result in r'$\frac{1}{8}$', which is then a valid MathText string.