在python / pandas中将字符串更改为整数

Question

I am trying to change a string to a float value in a dataframe.

#showing dataframe for illustration`

IN: df2[:5]

OUT:     TRD_EXCTN_DT   ASCII_RPTD_VOL_TX
    0    08/13/2010      1000000
    1    08/16/2010      1MM+
    2    08/16/2010      369000
    3    08/16/2010      1MM+
    4    08/16/2010      1MM+

output concatenates the string even though I thought I had changed it to a float. I need to operate on the number so a string does not work.

IN: df2.loc[df2['ASCII_RPTD_VOL_TX'] == '1MM+', 'ASCII_RPTD_VOL_TX'] = 1000005
df2.ASCII_RPTD_VOL_TX.astype(float)
df2['b'] = df2['ASCII_RPTD_VOL_TX'] + df2['ASCII_RPTD_VOL_TX']
df2[:3]

OUT:        TRD_EXCTN_DT   ASCII_RPTD_VOL_TX       b
    0        08/13/2010      1000000         10000001000000
    1        08/16/2010      1000005         2000010
    2        08/16/2010      369000          369000369000`

also,

In[22]:df2.dtypes

Out[22]:TRD_EXCTN_DT         object
ASCII_RPTD_VOL_TX    object
b                    object
dtype: object

Answer 1

You want to change your second line to df2['ASCII_RPTD_VOL_TX']=df2.ASCII_RPTD_VOL_TX.astype(float) .

The reason you are getting strange result is that your 1st and 3rd row, ASCII_RPTD_VOL_TX column cells are still in str . + is doing string concatenate there for those cells.