If greater than X assign 1

so I have a problem in python, which solution I just can't get into my head. Basically I have data frame df1a, which columns are of dtype "float64." Now I want to go through that data frame and assign a 1 if a specific criteria is met:

vs_pe = pd.DataFrame(index=date1, columns=df1a.columns) 
for x in df1a:
    if x < 5:
        vs_pe.loc[t] = 1

What I get is:

'<' not supported between instances of 'str' and 'int'

When I do:

vs_pe = pd.DataFrame(index=date1, columns=df1a.columns) 
for int(x) in df1a:
    if x < 5:
        vs_pe.loc[t] = 1

I'll get:

 invalid literal for int() with base 10:

Seriously I just tried everything, like transforming everything to integers using the to.numeric command, but nothing gives me the solution.

Would be happy if someone could help out.