how to find records starting with a particular letter in numpy array-CodePudding

i am beginner in numpy and created the following array

data=np.array([("abcd",111,9666),("atchd",222,6669),("cdef",444,8756)],dtype=[("name",str,10),("roll",int),("phone",int)])
print(data[data["name"][0]=='a']["name"])

I am trying to print records that have name property starting with character 'a' but this is returning empty array. pl update

CodePudding user response：

The problem is, that you can not index the "string-axis" of your data, since it is not part of the numpy array. To achieve the behaviour you expect, you can utilize np.char.startswith :

import numpy as np
data=np.array(
  [
    ("abcd",111,9666),
    ("atchd",222,6669),
    ("cdef",444,8756)
  ],
  dtype=[
    ("name",str,10),("roll",int),("phone",int)
  ]
)
print(data[np.char.startswith(data["name"], 'a')]["name"])
# ['abcd' 'atchd']

Note that there are also other string operations supported by numpy.