If Then statement

[zivoni]

Try to run/think over nilamo's point 3 - its same for your code. In body of your loop you set X to reference "cell" content, and after that you rebind X to a new value (NaN) - but you change just X, not dataframe cell. Its similar to

item = [1]
x = item[0]
x = 10

- if you check item list, it would be still [1] - unchanged.