[英]Apply a function with multiple arguments on an entire dataframe in Pandas
I have the following dataframe in pandas: 我在熊猫中有以下数据框:
df = pd.DataFrame({'field_1' : ['a', 'b', np.nan, 'a', 'c'], 'field_2': ['c', 'b', 'a', np.nan, 'c']}, index=[1,2,3,4,5])
I want to apply the following function on the entire dataframe that replaces each value with something else. 我想在整个数据框中应用以下功能,以其他方式替换每个值。
For example: 例如:
def func_replace(value, n):
if value == 'a':
return 'This is a'*n
elif value == 'b':
return 'This is b'*n
elif value == 'c':
return 'This is c'*n
elif str(value) == 'nan':
return np.nan
else:
'The value is not included'
so that the final product would look like (given that n=1
). 因此最终产品看起来像(假设
n=1
)。
For example: 例如:
df = pd.DataFrame({'field_1' : ['This is a', 'This is b', np.nan, 'This is a', 'This is c'], 'field_2': ['This is c', 'This is b', 'This is a', np.nan, 'This is c']}, index=[1,2,3,4,5])
I tried the following: 我尝试了以下方法:
df.apply(func_replace, args=(1), axis=1)
and bunch of other options, but it always gives me an error. 和其他选项,但这总是给我一个错误。
I know that I can write a for
loop that goes through every column and uses lambda function to solve this problem, but I feel that there is an easier option. 我知道我可以编写一个遍历每一列的
for
循环,并使用lambda函数来解决此问题,但是我觉得有一个更简单的选择。
I feel the solution is easier than I think, but I just can't figure out the correct syntax. 我觉得该解决方案比我想象的要容易,但是我无法弄清楚正确的语法。
Any help would be really appreciated. 任何帮助将非常感激。
Just modify your function to operate at the level of each value in a Series
and use applymap
. 只需修改您的函数以在
Series
中每个值的级别进行操作,然后使用applymap
。
df = pd.DataFrame({'field_1' : ['a', 'b', np.nan, 'a', 'c'], 'field_2': ['c', 'b', 'a', np.nan, 'c']}, index=[1,2,3,4,5])
df
Out[35]:
field_1 field_2
1 a c
2 b b
3 NaN a
4 a NaN
5 c c
Now, if we define the function as: 现在,如果我们将函数定义为:
def func_replace(value):
if value == 'a':
return 'This is a'
elif value == 'b':
return 'This is b'
elif value == 'c':
return 'This is c'
elif str(value) == 'nan':
return np.nan
else:
'The value is not included'
Calling this function on each value on the DataFrame
is very straightforward: 在
DataFrame
每个值上调用此函数非常简单:
df.applymap(func_replace)
Out[42]:
field_1 field_2
1 This is a This is c
2 This is b This is b
3 NaN This is a
4 This is a NaN
5 This is c This is c
I think you need: 我认为您需要:
def func_replace(df, n):
df_temp = df.replace({r"[^abc]": "The value is not included"}, regex=True)
return df_temp.replace(["a", "b", "c"], ["This is a " * n, "This is b " * n, "This is c " * n])
df.apply(func_replace, args=(2,))
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