select data based on a string criteria python

Question

I have a large database in which I want to select all the columns that meet a certain criteria:

My data looks like the following:

Name  a  b  c 
target-01  5196     24     24  
target-02  5950    150    150 
target-03  5598     50     50 
object-01  6558     44     -1 
object-02  6190     60     60

I want to select all the data whose Name starts with target.

So the selected df would be:

target-01  5196     24     24  
target-02  5950    150    150 
target-03  5598     50     50

I am reading the data using:

data = pd.read_csv('catalog.txt', sep = '\s+', header = None, skiprows =1 )

How can I select the data I want?

If you would like to apply further filtering of your data, you may take a look at the panda library: pandas.pydata.org — Phidelux
– Phidelux, Commented Aug 29, 2016 at 8:48

jezrael · Accepted Answer · 2016-08-29 08:38:42Z

2

Use str.startswith and boolean indexing:

print (df[df.Name.str.startswith('target')])
        Name     a    b    c
0  target-01  5196   24   24
1  target-02  5950  150  150
2  target-03  5598   50   50

Another solution with str.contains:

print (df[df.Name.str.contains(r'^target')])
        Name     a    b    c
0  target-01  5196   24   24
1  target-02  5950  150  150
2  target-03  5598   50   50

Last solution with filter:

df.set_index('Name', inplace=True)

print (df.filter(regex=r'^target', axis=0))
              a    b    c
Name                     
target-01  5196   24   24
target-02  5950  150  150
target-03  5598   50   50

print (df.filter(regex=r'^target', axis=0).reset_index())
        Name     a    b    c
0  target-01  5196   24   24
1  target-02  5950  150  150
2  target-03  5598   50   50

edited Aug 29, 2016 at 8:38

answered Aug 29, 2016 at 8:32

jezrael

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