How do I let column c with x divided by 20, with y divided by 30, and with z divided by 40. I tried np.where function but I failed
CodePudding user response：
df['c'][df['a'] == 'x'] = df['c'][df['a'] == 'x']/20
df['c'][df['a'] == 'y'] = df['c'][df['a'] == 'y']/30
df['c'][df['a'] == 'z'] = df['c'][df['a'] == 'z']/40
CodePudding user response：
You can use df.apply, which will apply a given function over each row in a pandas.DataFrame. df.apply returns a new pandas.DataFrame object with the new data.
def divide(row):
if row["a"] == "x":
row["c"] /= 20
elif row["a"] == "y":
row["c"] /= 30
elif row["a"] == "z":
row["c"] /= 40
return row
new_df = df.apply(divide, axis=1)