Counting unique values in a column in pandas dataframe like in Qlik

Question

If I have a table like this     df   pd DataFrame             hID    101  102  103  101  102  104  105  101             dID    10  11  12  10  11  10  12  10             uID     James    Henry    Abe    James    Henry    Brian    Claude    James              mID     A    B    A    B    A    A    A    C        I can do count distinct hID  in Qlik to come up with count of 5 for unique hID   How do I do that in python using a pandas dataframe   Or maybe a numpy array   Similarly  if were to do count hID  I will get 8 in Qlik   What is the equivalent way to do it in pandas

User · Answer

If I assume data is the name of your dataframe  you can do    data  race   value counts     this will show you the distinct element and their number of occurence

User · Answer

To count unique values in column  say hID of dataframe df  use   len df hID unique

User · Answer

Or get the number of unique values for each column   df nunique    dID    3 hID    5 mID    3 uID    5 dtype  int64     New in pandas 0 20 0 pd DataFrame agg  df agg   count    size    nunique              dID  hID  mID  uID count      8    8    8    8 size       8    8    8    8 nunique    3    5    3    5     You ve always been able to do an agg within a groupby   I used stack at the end because I like the presentation better   df groupby  mID   agg   count    size    nunique    stack                  dID  hID  uID mID                        A   count      5    5    5     size       5    5    5     nunique    3    5    5 B   count      2    2    2     size       2    2    2     nunique    2    2    2 C   count      1    1    1     size       1    1    1     nunique    1    1    1

User · Answer

Count distinct values  use nunique  df  hID   nunique   5  Count only non-null values  use count  df  hID   count   8  Count total values including null values  use the size attribute  df  hID   size 8  Edit to add condition Use boolean indexing  df loc df  mID     A   hID   agg   nunique   count   size     OR using query  df query  mID     quot A quot     hID   agg   nunique   count   size     Output  nunique    5 count      5 size       5 Name  hID  dtype  int64

User · Answer

you can use unique property by using len function     len df  hID   unique      5

User · Answer

You can use nunique in pandas   df hID nunique     5

[python] Counting unique values in a column in pandas dataframe like in Qlik?

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