在函数内迭代 Pandas 系列的行
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Iterating through rows of a Pandas series within a function
提问by Jason
I'm writing a function part of which should iterate through the rows of a Series. The function should iterate through rows of a DataFramecolumn passed to it i.e. df['col'], however when I try to use .iterrowsI get an error that a Seriesdoesn't have that attribute and using .iteritemsproduces the error below. Are there any other ways to iterate through rows of a column? I need do be able to access the index and column value.
我正在编写一个函数部分，它应该遍历 a 的行Series。该函数应该遍历DataFrame传递给它的列的行，即 df['col']，但是当我尝试使用时，.iterrows我收到一个错误，即 aSeries没有该属性，并且使用.iteritems会产生以下错误。还有其他方法可以遍历列的行吗？我需要能够访问索引和列值。
def get_RIMsin(df, obs, rimcol):
"""dataframe, obs column,rim column"""
maxval =df['Mmedian'].max()
minval =df['Mmedian'].min()
dfrange = maxval-minval
amplitude = dfrange/2
convert = (2*np.pi)/365
startday = obs.idxmax().dayofyear
sinmax = 91
for row in rimcol.iteritems: #This is where I'd like to go through rows of a series
diff = sinmax - startday
adjday = row.dayofyear + diff
adjsin = np.sin(adjday * convert)
df['RIMsine'] = row + adjsin
return df
get_RIMsin(sve_DOC, sve_DOC['DOC_mg/L'], sve_DOC['RIMsDOC'])
TypeError Traceback (most recent call last)
<ipython-input-98-4811cbf80e78> in <module>()
17 return df
18
---> 19 get_RIMsin(sve_DOC, sve_DOC['DOC_mg/L'], sve_DOC['RIMsDOC'])
20 """get_RIM2(svv_DOC, svv_DOC['DOC_mg/L'], svv_DOC['RIMsDOC'])
21 get_RIM2(svw_DOC, svw_DOC['DOC_filt_mg/l'], svw_DOC['RIMsDOC'])
<ipython-input-98-4811cbf80e78> in get_RIMsin(df, obs, rimcol)
10 sinmax = 91
11
---> 12 for row in rimcol.iteritems:
13 diff = sinmax - startday
14 adjday = row.dayofyear + diff
TypeError: 'instancemethod' object is not iterable
采纳答案by Dan Allan
None of this actually required row iteration, as Ryan G pointed out in the comments. I think this (untested!) code is equivalent.
正如 Ryan G 在评论中指出的那样，这些实际上都不需要行迭代。我认为这个（未经测试！）代码是等效的。
convert = (2*np.pi)/365
sinmax = 91
def get_RIMsin(df, obs, rimcol):
"""dataframe, obs column,rim column"""
amplitude = df['Mmedian'].ptp()/2
startday = obs.idxmax().dayofyear
diff = sinmax - startday
adjday = rimcol + diff
adjsin = np.sin(adjday * convert)
df['RIMsine'] = adjsin
return df
回答by gradi3nt
Use:
用：
rimcol.iteritems()
Since iteritems()is a function you must include the parenthesis. Otherwise you get an instance method object instead of an iterator that is returned by that instance method.
由于iteritems()是一个函数，您必须包含括号。否则，您将获得一个实例方法对象，而不是该实例方法返回的迭代器。
