pandas 对某列数据处理

1 、某列数据加1

from decimal import Decimal

def  add_df(x):
    x = 1 + Decimal(x)
    return x
# 对roc列+1 并赋值给列命为roc+1的列
df["rco+1"]= df['roc'].map(add_df)
df_line = np.cumprod(df['rco+1'][:]).tolist()

2、某列数据判断

import pandas as pd

df = pd.DataFrame([[1,  'A'], [3, 'B'], [3, 'C']], columns=list('AB'))

def add_extra_kwargs(column, **kwargs):
    return kwargs[column]
#方法 1
df['A'] = df.B.apply(add_extra_kwargs, A=0, B=10,C=5)
df['C'] = df["B"].apply(add_extra_kwargs,  A=0, B=10,C=5)
print(df)

def add_extra(field, extra):
    if field != "A":
        return extra
    else:
        return 0 
#方法 2
df['add_extra'] = df.B.apply(add_extra, args=(5,))
print(df)
df['extra'] = df.B.apply(add_extra, extra=5)
print(df)

3、某列数据时间格式转换

df['times '] = df['times '].apply(lambda x:x.strftime('%Y-%m-%d %H:%M:%S'))