Convert columns into rows with Pandas

Question

So my dataset has some information by location for n dates. The problem is each date is actually a different column header. For example the CSV looks like

location    name    Jan-2010    Feb-2010    March-2010 A           "test"  12          20          30 B           "foo"   18          20          25 

What I would like is for it to look like

location    name    Date        Value A           "test"  Jan-2010    12        A           "test"  Feb-2010    20 A           "test"  March-2010  30 B           "foo"   Jan-2010    18        B           "foo"   Feb-2010    20 B           "foo"   March-2010  25 

My problem is I don't know how many dates are in the column (though I know they will always start after name)

Answer 1

UPDATE
From v0.20, melt is a first order function, you can now use

df.melt(id_vars=["location", "name"],          var_name="Date",          value_name="Value")    location    name        Date  Value 0        A  "test"    Jan-2010     12 1        B   "foo"    Jan-2010     18 2        A  "test"    Feb-2010     20 3        B   "foo"    Feb-2010     20 4        A  "test"  March-2010     30 5        B   "foo"  March-2010     25 

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OLD(ER) VERSIONS: <0.20

You can use pd.melt to get most of the way there, and then sort:

>>> df   location  name  Jan-2010  Feb-2010  March-2010 0        A  test        12        20          30 1        B   foo        18        20          25 >>> df2 = pd.melt(df, id_vars=["location", "name"],                    var_name="Date", value_name="Value") >>> df2   location  name        Date  Value 0        A  test    Jan-2010     12 1        B   foo    Jan-2010     18 2        A  test    Feb-2010     20 3        B   foo    Feb-2010     20 4        A  test  March-2010     30 5        B   foo  March-2010     25 >>> df2 = df2.sort(["location", "name"]) >>> df2   location  name        Date  Value 0        A  test    Jan-2010     12 2        A  test    Feb-2010     20 4        A  test  March-2010     30 1        B   foo    Jan-2010     18 3        B   foo    Feb-2010     20 5        B   foo  March-2010     25 

(Might want to throw in a .reset_index(drop=True), just to keep the output clean.)

Note: pd.DataFrame.sort has been deprecated in favour of pd.DataFrame.sort_values.