pandas DataFrame中每一行的操作

Question

I want to iterate through every row in a pandas DataFrame, and do something with the elements in each row.

Right now I have

for row in df.iterrows(): 
    if row['col'] > 1.5:
        doSomething

but it tells me that the 'tuple indices must be integers, not str' . How do I access the column that I want in a certain row?

Answer 1

iterrows yields (index, Series) pairs. Therefore, use:

for index, row in df.iterrows(): 
    if row['col'] > 1.5:
        doSomething

Note, however, that a DataFrame is a primarily column-based data structure , so you'll get better performance if you can structure your code around column-wise operations, instead of row-wise operations.

Answer 2

Probably the simplest solution is to use the APPLYMAP or APPLY fucntions which applies the function to every data value in the entire data set.

You can execute this in a few ways:

df.applymap(someFunction)

or

df[["YourColumns"]].apply(someFunction)

The Links are below:

ApplyMap Docs

Apply Docs

Answer 3

You can use apply function with option axis=1 . For example:

def my_function(row):
    if row['col'] > 1.5:
        doSomething()
    else:
        doSomethingElse()

my_df.apply(my_function, axis=1)

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