hirolau - 1 year ago 117

Python Question

If i want to calculate the mean of two categories in Pandas, I can do like this:

`data = {'Category': ['cat2','cat1','cat2','cat1','cat2','cat1','cat2','cat1','cat1','cat1','cat2'],`

'values': [1,2,3,1,2,3,1,2,3,5,1]}

my_data = DataFrame(data)

my_data.groupby('Category').mean()

Category: values:

cat1 2.666667

cat2 1.600000

I have a lot of data formatted this way, and now I need to do a T-test to see if the mean of

Answer Source

it depends what sort of t-test you want to do (one sided or two sided dependent or independent) but it should be as simple as:

```
from scipy.stats import ttest_ind
cat1 = my_data[my_data['Category']=='cat1']
cat2 = my_data[my_data['Category']=='cat2']
ttest_ind(cat1['values'], cat2['values'])
>>> (1.4927289925706944, 0.16970867501294376)
```

it returns a tuple with the t-statistic & the p-value

see here for other t-tests http://docs.scipy.org/doc/scipy/reference/stats.html