如何从数据帧的单元格中获取值? [英] How to get a value from a cell of a dataframe?

问题描述

我构建了一个条件，可以从我的数据框中精确提取一行:

I have constructed a condition that extract exactly one row from my data frame:

d2 = df[(df['l_ext']==l_ext) & (df['item']==item) & (df['wn']==wn) & (df['wd']==1)]

现在我想从特定列中获取一个值:

Now I would like to take a value from a particular column:

val = d2['col_name']

但结果我得到一个包含一行和一列的数据框(即一个单元格).这不是我需要的.我需要一个值(一个浮点数).我怎样才能在熊猫中做到这一点?

But as a result I get a data frame that contains one row and one column (i.e. one cell). It is not what I need. I need one value (one float number). How can I do it in pandas?

推荐答案

如果您的 DataFrame 只有一行，则使用 iloc 作为系列访问第一(唯一)行，然后使用列名的值:

If you have a DataFrame with only one row, then access the first (only) row as a Series using iloc, and then the value using the column name:

In [3]: sub_df
Out[3]:
          A         B
2 -0.133653 -0.030854

In [4]: sub_df.iloc[0]
Out[4]:
A   -0.133653
B   -0.030854
Name: 2, dtype: float64

In [5]: sub_df.iloc[0]['A']
Out[5]: -0.13365288513107493

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