Code Sample, a copy-pastable example if possible

from pandas.compat import StringIO import pandas as pd t1 = """float 1 """ t2 = """float NaN """ for t in t1, t2: df = pd.read_csv(StringIO(t), dtype={'float': 'str'}) print(type(df['float'][0]))

Problem description

Even when explicitly specifying dtype above, read_csv still converts values in the float column to a float when the string is "NaN". This behavior appears to be limited to "NaN" as it doesn't happen for regular numbers. Still, I unexpectedly ran across a "NaN" string in my application so it's blocking me.