如何计算 Pandas DataFrame 中行之间的百分比增长？

Question

I have a data-frame such as:

 A   B(int64)
 1   100
 2   150
 3   200

now I need to calculate the growth rate and set it as an additional column such as:

 A    C
 1   naN
 2   50%
 3  33.33%

how can I achieve that? Thank you so much for your help!

Answer 1

Use Series.pct_change with multiple by 100 with Series.mul and rounding by Series.round :

df['C'] = df.B.pct_change().mul(100).round(2)
print (df)
   A    B      C
0  1  100    NaN
1  2  150  50.00
2  3  200  33.33

For percentage add map with format and processing with missing values with NaN != NaN :

df['C'] = df.B.pct_change().mul(100).round(2).map(lambda x: '{0:g}%'.format(x) if x==x else x)
print (df)
   A    B       C
0  1  100     NaN
1  2  150     50%
2  3  200  33.33%

Answer 2

You're looking for pct_change :

df['B'] = df.B.pct_change().mul(100).round(2)
df['B'] = df.B.where(pd.isna, df.B.astype(str).add('%'))

print(df)

   A       B
0  1     NaN
1  2   50.0%
2  3  33.33%