在 Python Pandas 中将列转换为行

我有以下 Python pandas 数据框：

     fruits | numFruits
---------------------
0  | apples |   10
1  | grapes |   20
2  |  figs  |   15

I want:

                 apples | grapes | figs
-----------------------------------------
Market 1 Order |    10  |   20   |  15

我看过pivot()、pivot_table()、Transpose 和unstack()，但它们似乎都没有给我这个。熊猫新手，所以感谢大家的帮助。

你需要set_index http://pandas.pydata.org/pandas-docs/stable/generated/pandas.DataFrame.set_index.html转置为T http://pandas.pydata.org/pandas-docs/stable/generated/pandas.DataFrame.T.html:

print (df.set_index('fruits').T)
fruits     apples  grapes  figs
numFruits      10      20    15

如果需要重命名列，则有点复杂：

print (df.rename(columns={'numFruits':'Market 1 Order'})
         .set_index('fruits')
         .rename_axis(None).T)
                apples  grapes  figs
Market 1 Order      10      20    15

另一个更快的解决方案是使用numpy.ndarray.reshape https://docs.scipy.org/doc/numpy/reference/generated/numpy.ndarray.reshape.html:

print (pd.DataFrame(df.numFruits.values.reshape(1,-1), 
                    index=['Market 1 Order'], 
                    columns=df.fruits.values))

                apples  grapes  figs
Market 1 Order      10      20    15

Timings:

#[30000 rows x 2 columns] 
df = pd.concat([df]*10000).reset_index(drop=True)    
print (df)


In [55]: %timeit (pd.DataFrame([df.numFruits.values], ['Market 1 Order'], df.fruits.values))
1 loop, best of 3: 2.4 s per loop

In [56]: %timeit (pd.DataFrame(df.numFruits.values.reshape(1,-1), index=['Market 1 Order'], columns=df.fruits.values))
The slowest run took 5.64 times longer than the fastest. This could mean that an intermediate result is being cached.
1000 loops, best of 3: 424 µs per loop

In [57]: %timeit (df.rename(columns={'numFruits':'Market 1 Order'}).set_index('fruits').rename_axis(None).T)
100 loops, best of 3: 1.94 ms per loop