Python - for loop with if

Question

could you please help me understand what's wrong in the script below and how to correct it? I am just trying to add a column iterating over the file. The new column should say 'F', if the percentage of females is higher than the percentage of males. Thank you very much!

babies_df = pd.read_csv('datasets/babynames_nysiis.csv', delimiter=';')
gender=[]
for idx in range(len(babies_df)):
 if babies_df['perc_female'>'perc_male']:
 gender.append('F')
 else:
 gender.append('M')
babies_df['gender'] = gender

• PSKP: I think you should use babies_df['perc_female'] > babies_df['perc_male']
• Michele Giglioni: thanks PSKP, tried that already but it does not work :(
• PSKP: In if statement you mistakenly comparing inside [ ] which is wrong. you should complete first column. If still error persist please add error also.
• Michele Giglioni: Sure, thanks for helping, this is the code: babies_df = pd.read_csv('datasets/babynames_nysiis.csv', delimiter=';') gender=[] for idx in range(len(babies_df)): if babies_df['perc_female’]> babies_df[’perc_male']: gender.append('F') else: gender.append('M') babies_df['gender'] = gender
• Michele Giglioni: and this is the error: ValueError Traceback (most recent call last) <ipython-input-195-cbb09ab25ce5> in <module>() 4 gender=[] 5 for idx in range(len(babies_df)): ----> 6 if babies_df['perc_female']>babies_df['perc_male']: 7 idx.append('F') 8 else:

Answer 1

The problem is that babies_df['perc_female'>'perc_male'] is not correct syntax.

You could try pandas apply for your solution.

babies_df = pd.read_csv('datasets/babynames_nysiis.csv', delimiter=';')
babies_df['gender'] = babies_df.apply(
 lambda x: 'F' if x['perc_female'] > x['perc_male'] else 'M', 
 axis=1
)

Answer 2

The problem with your code is, you are not iterating row by row and also you are comparing columns directly which is not possible.

babies_df = pd.read_csv('datasets/babynames_nysiis.csv', delimiter=';')
for index, row in babies_df.iterrows():
 if row["perc_female"] > row["perc_male"]:
 gender.append("F")
 else:
 gender.append("M")
babies_df["gender"] = gender