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)
Use .melt:
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
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.