检查该项目是否存在于列表中

Question

I have two sets like A={"sara", "peter", "ray"} and B={"ram", "sara", "gouri"}. I want to take one member of list B (for example "sara") and check with list A to see if this name exists in the list or not. If this name exists then print "yes". I want to check all the members in list B with list A. I have the code below but it doesn't work.

for i in B:
   if B[i]==A:
      print("yes")

Answer 1

It's easier than you think:

for i in B:
   if i in A:
      print("yes")

This assumes that both A and B are lists, but you seem to have dictionaries/sets. You might need to clarify that first. If you have sets, the above solution should still work.

Edit: you now say that both A and B are columns from two separate DataFrames. In that case you can do:

A={"sara", "peter", "ray"} 
B={"ram", "sara", "gouri"}

df1 = pd.DataFrame(A, columns=['Names'])
df2 = pd.DataFrame(B, columns=['Names'])

for index, row in df1.iterrows():
    if row['Names'] in df2.Names.tolist():
        print('yes')

Edit 2: you now say that you want to add the result to a new column in df2. Use:

A={"sara", "peter", "ray"} 
B={"ram", "sara", "gouri"}

df1 = pd.DataFrame(A, columns=['Names'])
df2 = pd.DataFrame(B, columns=['Names'])

df2['present_in_df1'] = np.where(df1['Names'] == df2['Names'], "yes", "no")

Output df2 :

    Names   present_in_df1
0   gouri   no
1   ram     no
2   sara    yes

Answer 2

I think you're looking for the in keyword. Breaking this down:

(for example "sara") and check with list A to see if this name exists in the list or not. If this name exists then print "yes"

if "sara" in B:
    print("yes")

I want to check all the members in list B with list A.

for b in B:
    if b in A:
        print("yes")