Need help in if loop

Question

I'm new to python coding and I do have the below simple list in my code.

Marks = [82,70,60,50,40,30]

Now my requirement is I want to get another column in my output called Result as below

So how to use if and else to achieve the output which i'm looking like

if Marks > 80 print 'Distinction'
if Marks >60 and Marks <= 70 print 'Grade A'
if Marks >50 and Marks <= 60 print 'Grade B'
if Marks >40 and Marks <= 50 print 'Grade C'
else print 'Good for Nothing'

See if this helps, https://stackoverflow.com/a/16992783/4985099 — sushanth, Aug 06 '20 at 02:49
Why **if-else**? You can use [`pd.cut`](https://pandas.pydata.org/pandas-docs/stable/reference/api/pandas.cut.html) try this `pd.cut(df['Marks'], [0,40, 50, 60, 70, 100],labels=['Good for nothing', 'C', 'B', 'A', 'Distinction'])` — Ch3steR, Aug 06 '20 at 03:54

score 3 · Answer 1 · answered Aug 06 '20 at 02:58

3

this is a good task for np.where:

df['Result'] = 'Good for Nothing'
df['Result'] = np.where((df['Marks'] > 80), 'Distinction', df['Result'])
df['Result'] = np.where((df['Marks'] > 60) & (df['Marks'] <= 70), 'Grade A', df['Result'])
df['Result'] = np.where((df['Marks'] > 50) & (df['Marks'] <= 60), 'Grade B', df['Result'])
df['Result'] = np.where((df['Marks'] > 40) & (df['Marks'] <= 50), 'Grade C', df['Result'])

answered Aug 06 '20 at 02:58

David Erickson

16,433
2
19
35

can this be achieved with if else statement? – Vikas Aug 06 '20 at 03:02
`np.select` and `np.where` will be similar performance-wise. @Vikas there is no optimal way in pandas to use the words `if` or `else` in a situation like this. `np.where` is similar to an excel if, then statement. – David Erickson Aug 06 '20 at 03:16

score 1 · Accepted Answer · answered Aug 06 '20 at 03:22

1

Marks = [82,70,60,50,40,30]
df = pd.DataFrame({'Marks' : Marks})
print(df)

def a(b):
if b['Marks'] > 80:
    return 'Distinction'
elif b['Marks'] > 69:
    return 'Grade A'
elif b['Marks'] > 59:
    return 'Grade B'
elif b['Marks'] > 49:
    return 'Grade C'
else:
    return 'Good for Nothing'

df['Result'] = df.apply(a, axis=1)
print(df)

answered Aug 06 '20 at 03:22

BALAJI R

129
1
9

Using Def & Return – BALAJI R Aug 06 '20 at 03:26
don't forget to indent the body of your function :) – David Erickson Aug 06 '20 at 03:51

score 0 · Answer 3 · answered Aug 06 '20 at 03:01

0

Try something like this in Python3

Marks = [82,70,60,50,40,30]

for i in Marks: 
    if i > 80:
        print('Distinction')
    elif i >60 and i <= 70:
        print('Grade A')
    elif i >50 and i <= 60:
        print('Grade B')
    elif i >40 and i <= 50:
        print('Grade C')
    else:
        print('Good for Nothing')

answered Aug 06 '20 at 03:01

Josh Kautz

459
3
5
31

thanks for that. How do i get the both the columns **Marks** and **Result** from the above output which i'm expecting? – Vikas Aug 06 '20 at 03:17
This is a great answer for how to print out the results in the terminal Josh, but I think the OP needs to get this in a dataframe. – David Erickson Aug 06 '20 at 03:24

Need help in if loop

3 Answers3