我在将函数应用于数据框时遇到了语法问题。我正在尝试通过使用分隔符连接两个其他列中的字符串来创建数据框中的新列。但是我遇到了错误。
TypeError: ("apply_join() missing 1 required positional argument: 'sep'", 'occurred at index cases')
如果我在apply_join()函数调用中添加sep,也会失败:
File "unite.py", line 37, in unite
tibble_extra = df[cols].apply(apply_join, sep)
NameError: name 'sep' is not defined
import pandas as pd
from io import StringIO
tibble3_csv = """country,year,cases,population
Afghanistan,1999,745,19987071
Afghanistan,2000,2666,20595360
Brazil,1999,37737,172006362
Brazil,2000,80488,174504898
China,1999,212258,1272915272
China,2000,213766,1280428583"""
with StringIO(tibble3_csv) as fp:
tibble3 = pd.read_csv(fp)
print(tibble3)
def str_join_elements(x, sep=""):
assert type(sep) is str
return sep.join((str(xi) for xi in x))
def unite(df, cols, new_var, combine=str_join_elements):
def apply_join(x, sep):
joinstr = str_join(x, sep)
return pd.Series({new_var[i]:s for i, s in enumerate(joinstr)})
fixed_vars = df.columns.difference(cols)
tibble = df[fixed_vars].copy()
tibble_extra = df[cols].apply(apply_join)
return pd.concat([tibble, tibble_extra], axis=1)
table3_again = unite(tibble3, ['cases', 'population'], 'rate', combine=lambda x: str_join_elements(x, "/"))
print(table3_again)