I have the following code.

I am trying to check if a 'date-time' value in the column **numberofeachconditiononthatdate['Date']** is in the column **'luckonthatdate['Date']'**.

If it is, then I want that particular date-time value to be assigned to the variable **'value'**.

If not, then I want the variable **'value'** to equal 0.

In other words, I want to create a new column of values to the **'numberofeachconditiononthatdate'** dataframe, indicating the number of 'luck' trials on a given date.

```
luckvalues = []

for idx in numberofeachconditiononthatdate.iterrows():
    if numberofeachconditiononthatdate['Date'][[idx]].isin(luckonthatdate['Date']):
       value = luckonthatdate['Date'][[idx]]
       luckvalues = luckvalues.append(value)
    else:
       value = 0
       luckvalues = luckvalues.append(value) 

print(luckvalues)

```

However, this gives me the error **'unhashable type: 'Series''**.

I would be so grateful for a helping hand!

```
numberofeachconditiononthatdate['Date']

0   2020-04-06
1   2020-04-06
2   2020-04-06
3   2020-05-06
4   2020-05-06
5   2020-05-06
6   2020-06-06
7   2020-06-06
8   2020-06-06
9   2020-06-13

luckonthatdate['Date'].head(10)

0    2020-04-06
3    2020-05-06
6    2020-06-06
9    2020-06-13
16   2020-10-06
20   2020-11-06
23   2020-12-06

```