Convert floats to ints in Pandas?

Considering the following data frame:

>>> df = pd.DataFrame(10*np.random.rand(3, 4), columns=list("ABCD"))
>>> print(df)
...           A         B         C         D
... 0  8.362940  0.354027  1.916283  6.226750
... 1  1.988232  9.003545  9.277504  8.522808
... 2  1.141432  4.935593  2.700118  7.739108

Using a list of column names, change the type for multiple columns with applymap():

>>> cols = ['A', 'B']
>>> df[cols] = df[cols].applymap(np.int64)
>>> print(df)
...    A  B         C         D
... 0  8  0  1.916283  6.226750
... 1  1  9  9.277504  8.522808
... 2  1  4  2.700118  7.739108

Or for a single column with apply():

>>> df['C'] = df['C'].apply(np.int64)
>>> print(df)
...    A  B  C         D
... 0  8  0  1  6.226750
... 1  1  9  9  8.522808
... 2  1  4  2  7.739108

Use the pandas.DataFrame.astype(<type>) function to manipulate column dtypes.

>>> df = pd.DataFrame(np.random.rand(3,4), columns=list("ABCD"))
>>> df
          A         B         C         D
0  0.542447  0.949988  0.669239  0.879887
1  0.068542  0.757775  0.891903  0.384542
2  0.021274  0.587504  0.180426  0.574300
>>> df[list("ABCD")] = df[list("ABCD")].astype(int)
>>> df
   A  B  C  D
0  0  0  0  0
1  0  0  0  0
2  0  0  0  0

EDIT:

To handle missing values:

>>> df
          A         B     C         D
0  0.475103  0.355453  0.66  0.869336
1  0.260395  0.200287   NaN  0.617024
2  0.517692  0.735613  0.18  0.657106
>>> df[list("ABCD")] = df[list("ABCD")].fillna(0.0).astype(int)
>>> df
   A  B  C  D
0  0  0  0  0
1  0  0  0  0
2  0  0  0  0

To modify the float output do this:

df= pd.DataFrame(range(5), columns=['a'])
df.a = df.a.astype(float)
df

Out[33]:

          a
0 0.0000000
1 1.0000000
2 2.0000000
3 3.0000000
4 4.0000000

pd.options.display.float_format = '{:,.0f}'.format
df

Out[35]:

   a
0  0
1  1
2  2
3  3
4  4

To convert all float columns to int

>>> df = pd.DataFrame(np.random.rand(5, 4) * 10, columns=list('PQRS'))
>>> print(df)
...     P           Q           R           S
... 0   4.395994    0.844292    8.543430    1.933934
... 1   0.311974    9.519054    6.171577    3.859993
... 2   2.056797    0.836150    5.270513    3.224497
... 3   3.919300    8.562298    6.852941    1.415992
... 4   9.958550    9.013425    8.703142    3.588733

>>> float_col = df.select_dtypes(include=['float64']) # This will select float columns only
>>> # list(float_col.columns.values)

>>> for col in float_col.columns.values:
...     df[col] = df[col].astype('int64')

>>> print(df)
...     P   Q   R   S
... 0   4   0   8   1
... 1   0   9   6   3
... 2   2   0   5   3
... 3   3   8   6   1
... 4   9   9   8   3