Show Negative values red

import pandas as pd
data = {
    'Month' : [1, 2, 3],
    'Temp' : [7, -18, -20]
}
data
{'Month': [1, 2, 3], 'Temp': [7, -18, -20]}

type(data)
dict

df = pd.DataFrame(data)
df
Month Temp
0 1 7
1 2 -18
2 3 -20 
def color_negative_red(val):
    """
    Takes a scalar and returns a string with
    the css property `'color: red'` for negative
    strings, black otherwise.
    """
    color = 'red' if val < 0 else 'black'
    return 'color: %s' % color
df.style.applymap(color_negative_red)

Month Temp
0 1 7
1 2 -18
2 3 -20 

df
Month Temp
0 1 7
1 2 -18
2 3 -20 
# Highlight max (axis = 0)
# https://pandas.pydata.org/pandas-docs/stable/user_guide/style.html

df.style.highlight_max(axis = 0)

Month Temp
0 1 7
1 2 -18
2 3 -20 

def highlight_max_rj(s, color = 'lightgreen'):
    '''
    highlight the maximum in a Series yellow.
    '''
    is_max = s == s.max()
    return ['background-color: '+color if v else '' for v in is_max]
df.style.apply(highlight_max_rj, color = 'lightblue',  axis = 0, subset=['Temp'])

Month Temp
0 1 7
1 2 -18
2 3 -20 

df.style.apply(highlight_max_rj, axis = 1, subset = ['Temp'])

Month Temp
0 1 7
1 2 -18
2 3 -20