calculate percentile pandas dataframe

import pandas as pd
import random

A = [ random.randint(0,100) for i in range(10) ]
B = [ random.randint(0,100) for i in range(10) ]

df = pd.DataFrame({ 'field_A': A, 'field_B': B })
df
#    field_A  field_B
# 0       90       72
# 1       63       84
# 2       11       74
# 3       61       66
# 4       78       80
# 5       67       75
# 6       89       47
# 7       12       22
# 8       43        5
# 9       30       64

df.field_A.mean()   # Same as df['field_A'].mean()
# 54.399999999999999

df.field_A.median() 
# 62.0

# You can call `quantile(i)` to get the i'th quantile,
# where `i` should be a fractional number.

df.field_A.quantile(0.1) # 10th percentile
# 11.9

df.field_A.quantile(0.5) # same as median
# 62.0

df.field_A.quantile(0.9) # 90th percentile
# 89.10000000000001