使用Pandas对现有Excel工作表进行操作

Question

I have two csv files and I have merged the csv files and exported them to an Excel sheet.

Now can I add a new column in the existing Excel sheet where the result of the new column will be division operation of two columns existing.

Example:

col_new=col4/col6

I have tried to implement with csv files where after merging the files the final csv file would be like this:

col1,col2,col3
"1,200",14,2
"1,600",13,4

data=pd.read_csv(filename)

for i,l in zip(data['col1'],data['col3']):

    sah=i.replace(',','')
    sah1=int(float(sah))
    print sah1
    print type(sah1)
    data['res']=sah1/l
    print data

Expected:

col1    col2   col3   res
---------------------------
1,200    14      2    600
1,600    13      4    400

Answer 1

You can convert the first column to an integer using str.replace(',','') as you have done and then use pd.to_numeric() to recast the entire series at once. Now that you have the two columns you're interested in as integers, just use the ability to divide one series by another and store that in res . From there, you can export it to a csv or excel file.

# set up the DataFrame to match your input
df = pd.DataFrame([["1,200", 14, 2],["1,600", 13, 4]], columns=['col1','col2','col3'])
print(df)
#     col1  col2  col3
# 0  1,200    14     2
# 1  1,600    13     4

df['res'] = pd.to_numeric(df.col1.str.replace(',','')) / df.col3
print(df)
#     col1  col2  col3    res
# 0  1,200    14     2  600.0
# 1  1,600    13     4  400.0

Part of the issue I see in your code is data['res']=sah1/l is saying data['res'] is a scalar. So it will fill the entire column with that singular value rather than evaluating row wise. It will do this each iteration which is why you see the res column the same every time it prints.