当使用加法运算符+将列与字符串连接起来时，如果其中任何一个是NaN，则整个输出将是NaN，因此使用fillna()

df["join"] = "some" + df["col"].fillna(df["val_if_nan"])

泛化到多个列，为什么不呢:

columns = ['whatever', 'columns', 'you', 'choose']
df['period'] = df[columns].astype(str).sum(axis=1)

可以使用DataFrame的assign方法:

df= (pd.DataFrame({'Year': ['2014', '2015'], 'quarter': ['q1', 'q2']}).
  assign(period=lambda x: x.Year+x.quarter ))

类似于@geher的答案，但可以使用任何你喜欢的分隔符:

SEP = " "
INPUT_COLUMNS_WITH_SEP = ",sep,".join(INPUT_COLUMNS).split(",")

df.assign(sep=SEP)[INPUT_COLUMNS_WITH_SEP].sum(axis=1)

使用zip可以更快:

df["period"] = [''.join(i) for i in zip(df["Year"].map(str),df["quarter"])]

图:

import pandas as pd
import numpy as np
import timeit
import matplotlib.pyplot as plt
from collections import defaultdict

df = pd.DataFrame({'Year': ['2014', '2015'], 'quarter': ['q1', 'q2']})

myfuncs = {
"df['Year'].astype(str) + df['quarter']":
    lambda: df['Year'].astype(str) + df['quarter'],
"df['Year'].map(str) + df['quarter']":
    lambda: df['Year'].map(str) + df['quarter'],
"df.Year.str.cat(df.quarter)":
    lambda: df.Year.str.cat(df.quarter),
"df.loc[:, ['Year','quarter']].astype(str).sum(axis=1)":
    lambda: df.loc[:, ['Year','quarter']].astype(str).sum(axis=1),
"df[['Year','quarter']].astype(str).sum(axis=1)":
    lambda: df[['Year','quarter']].astype(str).sum(axis=1),
    "df[['Year','quarter']].apply(lambda x : '{}{}'.format(x[0],x[1]), axis=1)":
    lambda: df[['Year','quarter']].apply(lambda x : '{}{}'.format(x[0],x[1]), axis=1),
    "[''.join(i) for i in zip(dataframe['Year'].map(str),dataframe['quarter'])]":
    lambda: [''.join(i) for i in zip(df["Year"].map(str),df["quarter"])]
}

d = defaultdict(dict)
step = 10
cont = True
while cont:
    lendf = len(df); print(lendf)
    for k,v in myfuncs.items():
        iters = 1
        t = 0
        while t < 0.2:
            ts = timeit.repeat(v, number=iters, repeat=3)
            t = min(ts)
            iters *= 10
        d[k][lendf] = t/iters
        if t > 2: cont = False
    df = pd.concat([df]*step)

pd.DataFrame(d).plot().legend(loc='upper center', bbox_to_anchor=(0.5, -0.15))
plt.yscale('log'); plt.xscale('log'); plt.ylabel('seconds'); plt.xlabel('df rows')
plt.show()

该解决方案使用中间步骤，将DataFrame的两列压缩为包含值列表的单列。 这不仅适用于字符串，而且适用于所有类型的列-dtype

import pandas as pd
df = pd.DataFrame({'Year': ['2014', '2015'], 'quarter': ['q1', 'q2']})
df['list']=df[['Year','quarter']].values.tolist()
df['period']=df['list'].apply(''.join)
print(df)

结果:

   Year quarter        list  period
0  2014      q1  [2014, q1]  2014q1
1  2015      q2  [2015, q2]  2015q2