Eligibility:

• Merge on index pandas stack. stack. I am given a list of column index col_index = [3, 5] for example. If you used groupby and want to replace the index into the default RangeIndex, there is the as_index parameter when passed False resets the index Yes, since pandas 0. import datetime. merge # pandas. Return a reshaped DataFrame or Series having a multi-level index with one or more new inner-most levels compared to the current DataFrame. 56. drop(columns='dummy') And subset to the dates that fall in between the ranges: df[(df. Oct 20, 2015 · 1. left: use only keys from left frame, similar to a SQL left outer join Jul 17, 2021 · This means that the old index is removed and replaced with a RangeIndex from 0. インデックス上の 2つの DataFrames を結合する場合、関数 merge() のパラメータ left_index と right_index の値は True でなければなりません。. merge(df2, left_index=True). start = datetime. DataFrame. stack() and unstack(): Pivot a column or row level to the opposite axis Jun 14, 2019 · The type of merge to be performed is wrong. set_index('id'). tolist(),pw. When saving a pandas. I would do something like this: Thanks for contributing an answer to Stack Overflow! Please be sure to answer the question. Dec 6, 2018 · When merging on keyLeft from left and keyRight from right, if you only want either of the keyLeft or keyRight (but not both) in the output, you can start by setting the index as a preliminary step. To set the index, just assign to it: s2 = pd. Assign value is also sometimes slow. set_index('keyLeft') left3. Now the index in the original questions has three levels, so each argument passed to the format function is a tuple containing the three elements corresponding to the row's index. Apr 13, 2019 · I have 2 Dataframes as below: Dataframe1: 6 count store_1 10 store_2 23 store_3 53 Dataframe2: store_name location store_1 location_a store_2 location_b I am trying to jo Oct 26, 2018 · I tried to do df1 = pd. join(df2, how='inner') # how='outer' keeps all records from both data frames. 050773. 0780 5 vitamin-b 0. 0150 2 vitamin-c 0. Here's what happens: the output index is the intersection of the index/column merge keys [0, 1]. The original index becomes a column and a new RangeIndex is created. df = df1. merge(df1, df2, on='ID', how='outer') I have data frame like this: index x y z 0 2 NaN 3 0 NaN 3 3 1 2 NaN 4 1 NaN Skip to main content Stack Overflow Aug 26, 2020 · The Importance of ignore_index. Aug 12, 2020 · I would like merge rows that are from the same transaction. My idea was to find each row number with the string 'Date' and merge those rows. Field names are different so concat is out. datetime(2002, 1, 1) I have a pandas dataframe test_df. I did find another solution which was: df2. df. step 1: use reset_index() to release the index into a column called Jan 21, 2018 · I notice that pandas is very slow on merge DataFrames based on MultiIndex. 0007 vitamin-c 1. So if you calculate intervals in each dataframe, you can match on 'UniqueID' and 'Interval'. droplevel(1). values. col2 to_merge_on. The 2nd Dataframe basically overlaps the 1st and they thus both share rows with same timestamps and values. iloc May 15, 2017 · Do something like this: Use . I hoped this might be as simple as reassigning the old index, but it looks like there are no ordering guarantees after a merge. ex_dict[df1] date df1price1 df1price2. The easiest way is to reindex the dfs and then call update to overwrite the NaNs at the desired rows: Jul 1, 2022 · 1. Provide details and share your research! But avoid … Asking for help, clarification, or responding to other answers. DF1. sum(level=0) is a good alternative that can be added to the dupe so that all options are in one place. DataFrame の merge() メソッドを使う。. 以下のコード例は、 inner を結合型とする 2つの This is different from usual SQL join behaviour and can lead to unexpected results. I think if you make these your last two lines it will work. Note that in the previous examples we used ignore_index=True. You need to change your keyword argument on the how parameter. stack(). While I could avoid using indexing all together, I need them. import os. e. 5 2012-01-03 YYYY 6. Jul 10, 2020 · Let's say I have two data frames df1 and df2 and I want to merge them. drop(columns='cities') Can't I choose which columns I want to merge into the left dataset? What if df2 had 30 columns and I only want 10 of them? Jan 22, 2018 · Otherwise it just adds a second data point to the same index/column. b 3 4. I want to merge all of these dataframes into one dataframe by date. For example this will be output of that For example this will be output of that id_x name_x id_y name_y 0 1 x 34 a 1 2 y 35 b 2 3 z 36 z Value of Reciever key is SOURCE_KEY 1. Apr 11, 2016 · You can do this with merge: df_merged = df1. catcode_amt type feccandid_amt amount. jwzinserl. Note: The function assumes that the dataframe and series have the same length. import random. I would like to remove these rows because they share everything: index and values in columns. 14, you can simply join single-index and multiindex dataframes. Feb 23, 2022 · I think you're looking for stack method, which converts columns to index. merge(df1, df2, on=['user-reference_id'], how='outer') There are a couple of links that are related e. left vs inner join: df1. merge(df1, df2) or df1 Jun 5, 2017 · Meanwhile in pandas the only way (that's not using loops that I found), is by creating a dummy column in both tables, join on it (equivalent to cross-join) and then filter out unneeded rows. Dec 4, 2014 · Or if the merge is to be performed in a parallel manner (bw and pw have the same index, same number of items). Pandas/Python: How to concatenate two dataframes 1. Or this. . When you reset_index() a series, it turns to a DataFrame (index to column). インデックス列を基準にする場合は pandas. This tells pandas to ignore the index numbers in each DataFrame and to create a new index ranging from 0 to n-1 for the new DataFrame. missingnames needs to be changed to: missingnames = df1. index # => Int64Index i1 but I want the i1, i2 index to remain. second, merging the two dataframes and renaming the series' column. File "<ipython console>", line 1, in <module>. set_index('id') Step 2: Set index of the second dataframe (df2) df2. JoeCondron. 8,786 3 27 28. For example: #required packages. I can manually use df[0]. I want to combine them and use multi-index so that each KPI can be easily compared to the other for the two df. Aug 21, 2018 · Now merge it all together. The left_index and right_index keyword arguments have the merge be done on the indices. The how argument works as expected with 'inner' and 'outer', though interestingly it seems to be reversed for 'left' and 'right' (could this be a bug?). The new inner-most levels are created by pivoting the columns of the current dataframe: Jan 30, 2023 · インデックス上の 2つの Pandas の DataFrame を結合するには merge() を使用する. merge(df2, left_on='name', right_index=True) Out[404]: name age id 1 bob 10 10 sally 11 You could append 'cuspin' and 'idc_id' as a indices to your DataFrames before you join (here's how it would work on the first couple of rows):. The join is done on columns or indexes. join(): Merge multiple DataFrame objects along the columns. Since the map method will pass a single index entry as argument to the format function, "{0[2]}" refers to the third element of that index. Stack the prescribed level (s) from columns to index. dates1 = pd. to_csv(path, index=False) Method 2 Jul 15, 2021 · Self-answer. merge() 関数または pandas. e, col1 to_merge_on. RECIEVER_KEY 2. DataFrame to disk, use index=False like this: df. Jan 1, 2018 · The problem is two folds: merging the csv into a single dataframe, and then ordering it by date. index = norm_df. out = df. That can be overridden by specifying df1. tolist()) merged = pd. you can do it by following steps —. answered May 12, 2015 at 14:57. As John Smith pointed out to merge dataframes along rows, you need to use: df = pd. 048725 0. The 0. Value of Reciever key is SOURCE_KEY 2. The new inner-most levels are created Jan 11, 2021 · use workers_df. loan_amnt grade term A 36 months 3. merge(geoid, how='outer', on=list(original. 0. 45. 0004 vitamin-a 0. Name: 1, dtype: int64. index = df. merge(df,d, how='inner', left_index=True, right_index=True) Sample (first value of index in d was changed for matching): print df. start) & (df. Sep 6, 2016 · let's say i have the following two dataframes X1 and X2. Object to merge with. If you want to join on indices, just do df = pd. 10-20-2015 100 150. Mar 19, 2019 · 7. join(df2) does a left join by default (keeps all rows of df1), but df. index = s. merge(bed_template_df, norm_df, left_index=True, right_index=True) but the result is an empty data. merge(left, right, how='inner', on=None, left_on=None, right_on=None, left_index=False, right_index=False, sort=False, suffixes=('_x', '_y'), copy=None, indicator=False, validate=None) [source] # Merge DataFrame or named Series objects with a database-style join. set_index('name') In [404]: df1. merge(geoid, how='inner', on=list(original. reset_index() Output: id children. merge(df2, left_index=True, right_index=True) answered May 14, 2020 at 16:35. duplicated(keep='last'), 'duration'] = df2['duration'] If you want to fix the already existing column (e. reset_index(drop=True) # <--- must assign to dataframe. stack(level=-1, dropna=_NoDefault. sort_values(by = 'Data Nov 30, 2012 · In order to fuzzy-join string-elements in two big tables you can do this: Use apply to go row by row. date. columns)) # This duplicates the data so that it includes data from both dataframes. The dates are overlapping, but not all dataframes include all dates. For example, consider what happens when we don’t use ignore_index=True when stacking the following two DataFrames: Jan 31, 2018 · I have two dataframes like the following: df1: dp value 0 d1 2 1 d1 3 2 d2 7 3 d2 8 4 d3 6 df2: fv_name dp value 0 x-1 d1 2 1 x-2 d1 2 2 Sep 6, 2022 · merged. dropping the duplicates in df2? Sep 24, 2018 · 1. Jan 10, 2011 · Hello, I have the following two dataframes (df1, df2) and if I merge them (inner join), I get the following dataframe: In [85]: df1 = pd. to give the following result: hzdept_r hzdepb_r sandtotal_r. df = original. to merge each df one by one, but the issue is that the number of data frames in the list differs with user input. 2 In [11]: dfL1 = dfLeft. Mar 16, 2019 · Stack Overflow Public questions & answers; Merge Multi-Index Pandas Data Frames. Jul 18, 2017 · After merging of two data frames: output = pd. assign(dummy=1), on='dummy'). 1 7 nan nan nan. Jul 25, 2017 · I have two dataframes with KPIs by date. And . Oct 12, 2021 · I have a pandas DataFrame and I want to merge the rows with grade E, F, G into a group named 'Others'. import numpy as np. pandas provides various methods for combining and comparing Series or DataFrame. will give you tuples in a single level if that's what you mean by 'merge'. you sound like you know your merges so change the behavior to match your requirement. After trying various ways, I find the following is more or less intuitive, provided stack 's magic is understood: # keep topic as index, stack other columns 'against' it. py", line 2054, in set_index. df1 includes "Player" and "Category" df2 includes "Player Name", "Height" and "Weight". Using the pandas merge operations does not work since it just lines the dataframes horizontally (and not vertically, which is what I want) Jun 23, 2017 · I'm trying to merge two Pandas DataFrames, where (possibly) there are some duplicate records. merge(left, right, how = 'inner', right_index = True, left_index = True) # If you make matching unique multi-indexes for both data frames you can do. 1. Doing. Nov 15, 2021 · How can I join/merge two Pandas DataFrames with partially overlapping indexes, where I wish the resulting joined DataFrame to retain the column values in the first DataFrame i. 2 May 12, 2015 · 1. 14. df1. df1 Name Age Sex 0 Tom 34 M 1 Sara 18 NaN 2 Eva 44 F 3 Jack 27 M 4 Laura 30 NaN May 16, 2018 · 6. Parameters. It will match on the common index name. pandas. So here, you could do: In [403]: df2 = df2. groupby('Products'). g. Aug 27, 2019 · I want to merge two dataframe df1 and df2 and use the script below: import pandas as pd df1 = pd. sort_values(by = 'Data') instead . 2000 vitamin-e 1. rightDataFrame or named Series. Name: 2, dtype: int64. merge_asof(df_t, y_df, left_index=True, right_index=True, by='stock_id'). See full list on statology. You'll get 99x10K rows. How to merge the frames using one column in df1 and the index of df2? Simple example would go Mar 21, 2018 · I am having difficulty: Merging two pandas multiindex dataframes; Passing an offset to a datetimeindex in the merge; df1: date ID Attr_1 12/31/2010 13 A 9 B 1 C 1/31/2011 13 D 9 E 1 F May 27, 2021 · The pandas melt function appears to do the job, or at least part of it, and with pivot_table can get all the way. set_index('id') and finally update the dataframe using the following snippet —. DataFrame({'value' : [11, 15, 16]}, index=[1, 3, 3]); df2 Out[86]: value 1 11 3 15 3 16 In [87]: pd. DataF pandas. The related DataFrame. Value of SOurce key is 2. 38259"]. merge(df1, df2, how='inner', left_index Jan 2, 2020 · On or left_on/right_on must be given. I wanto to turn it into a single index to have a dataframe like this: May 12, 2020 · 1. c = zip(bw. merge(df2. This is definitely a duplicate. In the below example, I can get the merge to run correctly, but how do I not have the second index print as well? Do I have to add a separate line of code: df_merge = df_merge. merge(s, df, how='left', left_index=True, right_on='id') s2. I wonder why this works. 14 pandas docs describes this as equivalent but more memory efficient and faster than: Mar 21, 2021 · first, by converting to the series to a dataframe, and setting its index using the dataframe's index, and. shift(1) new_df = df1. Sep 10, 2021 · df = original. Temp = pd. date <= df. 2020 4 vitamin-a 0. no_default, sort=_NoDefault. import datetime as dt. rename('children'). How do I stack the following 2 dataframes: hzdept_r hzdepb_r sandtotal_r. In this case rows [0, 1] and [2, 3]. join. Links provided by @JvdV should cover your requirements. I need to create two separate dataframes . DataFrame をその列の値に従って結合するには、 pandas. import pandas as pd. stacked = df. index = bed_template_df. columns)) This is the result I'm looking for Stack Overflow Public questions & answers; Python / Pandas - Merge columns with the same index in a single cell. loc[~df1. Jul 9, 2019 · bed_df = pd. Words Score The Man 2 The Girl 4 Df2 . Type of merge to be performed. The dataset I'm using is large, and I need the speed up gained when merging with Merge DataFrame or named Series objects with a database-style join. join(df2, on=key_or_keys) or df1. 0) Combines exactly two DataFrame horizontally; Aligns the calling DataFrame's column(s) or index with the other DataFrame's column(s) or index; Handles duplicate values on the joining columns or index by performing a cartesian product pandas. But it also has nan and may contains characters where no corresponding rownames in df2 exists. DataFrame. Words3 Score3 The Son 3 The Daughter 4 Reshaping and pivot tables. merge(left, right, how = 'inner', on = ['indexname1', 'indexname2']) left_index=True, right_index=True will merge 0th row of student_df with 0th row staff_df. If the index is meaningful to the dataframe, (for example it contains actual IDs for each player), first reset the index. set_index. vento0 = vento1. " The online documentation for pandas is also (1/2) – sodd Oct 12, 2018 · I wanted to ask a questions regarding merging multiindex dataframe in pandas, here is a hypothetical scenario: arrays = [['bar', 'bar', 'baz', 'baz', 'foo', 'foo merge is a function in the pandas namespace, and it is also available as a DataFrame instance method, with the calling DataFrame being implicitly considered the left object in the join. df1 has a multi-index on columns and df2 consists of one multi-index column with an index. merge(df2, how='outer', left_index=True, right_index=True) The keyword argument how='outer' keeps all indices from both frames, filling in missing indices with NaN. Nov 6, 2017 · If you add names to the index/multiindex you can use a join: In [11]: df Out[11]: energy fat n 1 2000 28 2 1900 17 3 2200 30 4 1750 15 5 1800 18 6 1600 12 In [12]: df2 Out[12]: val n vitamin 1 vitamin-c 0. combine_first(): Update missing values with non-missing values in the same location. Sep 5, 2017 · df1 has a column v2 that contains character values that match the index of df2. Jul 23, 2023 · 共通のデータ列を持つ複数の pandas. That is why you can merge after that. new_df = df. : Difference (s) between merge () and concat () in pandas. In [10]: dfL Out[10]: cuspin factorL date 2012-01-03 XXXX 4. dropna(ignore_index=True, inplace=True) # <--- `df` modified in-place. # pd. Look closer at your merge argument and the columns you have in each dataframe. left3 = left2. Then when you go to merge, you have df1 with a regular integer index and df2 with a MultiIndex of date and filename. pandas provides methods for manipulating a Series and DataFrame to alter the representation of the data for further data processing or data summarization. one only including the columns in col_index; other includes all the columns except the columns in col_index; How do I do that? I understand I can do. RECIEVER_KEY 3. Example: pd. df1 = df. merge(df2,left_on='Player',right_on Feb 19, 2017 · There it is stated: "pandas’s Index objects are responsible for holding the axis labels and other metadata (like the axis name or names). set_index('idc_id', append=True) In [13]: dfL1 Out[13]: factorL date cuspin 2012-01-03 Jan 22, 2019 · A similar question was asked in How to keep index when using pandas merge, but it will not work with MultiIndexes, i. Dec 20, 2015 · 7. frame. In this way, you can use inplace parameter as well. join(df2 Mar 30, 2015 · 44. Use merge function along with index reset and set after matching your column (s). To learn more, see our tips on writing great Jan 4, 2013 · According to the documentation, as of pandas 0. DataFrame({'A': ['A0', 'A1', 'A2'], 'B': ['B0', 'B1', 'B2']}) df2 Feb 28, 2020 · Pandas group-by and sum. Just a suggestion. # create sample time series. This is different from usual SQL join behaviour and can lead to unexpected results. set_index('cuspin', append=True) In [12]: dfR1 = dfRight. If joining columns on columns, the DataFrame indexes will be ignored. merge () changes the column names, if they exist in both the left and right data frame. #. 0 1 No Children. Jul 18, 2019 · The thing is, I will use this dataframe later to merge with others and the multiindex is not good for me. Making statements based on opinion; back them up with references or personal experience. merge(df[1],on='Date'). reset_index(), how='left', on='state') The column state is on the index, so you can move it into your normal dataframe columns as you merge with the other dataframe on the same column name. concat(): Merge multiple Series or DataFrame objects along a shared index or column. merge(right, how='inner', on=None, left_on=None, right_on=None, left_index=False, right_index=False, sort=False, suffixes=('_x', '_y'), copy=None, indicator=False, validate=None) [source] # Merge DataFrame or named Series objects with a database-style join. sum() meets the needs of the OP. merge(df1, df2, how='outer', on=['A'], right_index=True) looks a little weird to me. merge(df1, df2, on = 'Name', how = 'outer') but I keep the information of some people in df2 that I don't want. Otherwise if joining indexes on indexes or indexes on a column or columns, the index will be passed on. after concat): I have two pandas DataFrames that I want to merge. join method, uses merge internally for the index-on-index (by default) and column (s)-on-index join. Step 1: Set index of the first dataframe (df1) df1. And yes -- "I really want to learn Python/Pandas/Numpy to be able to move away from Excel and streamline work projects" That Sep 19, 2018 · What is the quickest way to merge to python data frames in this manner? I have two data frames with similar structures (both have a primary key id and some value columns). I now want to merge these data frames to one, like this: v1 v2 pc1 pc2. columns)) # This produces an empty dataframe. index) should have the same result. 0030 3 vitamin-d 1. index. merge(right2, left_index=True, right_on='keyRight') value_x keyRight value_y. It is complaining because you are giving it values instead of a name of a column to join on. Like this: I have tried to extract each KPI into a series, rename the series accordingly (df1, df2), and then concatenating them using the keys argument of pd. missing keys are replaced with NaN. merge does an inner join by default (returns only matching rows of df1 and df2). Dec 11, 2016 · In summary, what you're doing is saving the index to file and when you're reading back from the file, the column previously saved as index is loaded as a regular column. This dataframe contains 20 columns. I have tried to set up the same type to both indexes. 10-21-2015 90 100. merge # DataFrame. DataFrame({'value' : [10, 11, 14, 16]}, index=[1, 2, 3, 3]); df1 Out[85]: value 1 10 2 11 3 14 3 16 In [86]: df2 = pd. 813408e+09 60 months 4. 9650 6 vitamin-e 1. Thanks for the feedback. B['dummy'] = 1. sort_values(by = 'Data') vento_time0 = vento_time. 0 5 a1 0. Dec 6, 2018 · A similar but different question was asked here How to keep index when using pandas merge but I don't really understand the answers and so can't relate it to my problem. set_index('topic'). how{‘left’, ‘right’, ‘outer’, ‘inner’, ‘cross’}, default ‘inner’. 0, it is now possible to merge a singly-indexed DataFrame with a level of a multi-indexed DataFrame using . update () does not append data, if the column / row does not yet exist. norm_df. merge(geoid, how='right', on=list(original. @jezrael df. DataFrame を縦横に連結するに I have two pandas dataframes that I would like to merge/join together. Words2 Score2 The Boy 6 The Mother 7 Df3 . pivot() and pivot_table(): Group unique values within one or more discrete categories. import string. I access a dataframe in the following way. It says let's join two tables on column A and also the index of the right table with nothing on the left table. astype(str) bed_template_df. See for instance this post: pandas: merge (join) two data frames on multiple columns . When you do the groupby, I believe that will return a dataframe with a MultiIndex. Now to get the exact shape, you'll need to set_index with "id" first (so that "id" is kept as index when stack ing). date >= df. score id value. If you want to update/replace the values of first dataframe df1 with the values of second dataframe df2. The index of df2 has a name that coincides with a name (at level 1) of one column in df1. Change it to: table = pd. 9801 vitamin-c 1. def merge_df_series(x, y): Oct 1, 2014 · Lets say i Have 3 Pandas DF. You can add parameters left_index=True and right_index=True if you need merge by indexes in function merge: merge=pd. from pandas_datareader import data. That sounds heavy and complex: A['dummy'] = 1. The merge works as expected, but unfortunately, it seems to reset the index. dropna(). Actual dataframe is little different but let me follow the dataframe of the example. They have timestamps as indexes. no_default, future_stack=False) [source] #. merge(A,B,on='dummy') DataFrame. For simplicity, coding for 'g h t - - 6' is omitted. There are a few ways to deal with this: Method 1. index(str) But it doesn't work, when I specified the how in the merge command I get this result pd. you can create a new df2 column with the shifted column and then merge it normally with df1: df2["shifted_col"] = df2["1. It is taking the value "i" as index and renaming as source_key and receiever_key. stack() # set the name of the new series created. merge (df1, left_index=True, right_on='row_no') I did try this before, where reset_index was used. File "C:\Python27\lib\site-packages\pandas\core\frame. melt does a sort of un-pivot, and if we use it on your '00' through '23' columns, it flips those to being in the rows. merge(df[3],on='Date) etc. 0011 In [13]: df. So, the generic approach is to use pandas. concat([df1,df2,df3]) Then you want to set an index and reorder your dataframe according to the index. If you tried to merge using the indices then they will clash and create additonal columns e. Jan 5, 2021 · Stack Overflow Public questions & answers; Stack Overflow for Teams Where developers & technologists share private knowledge with coworkers; Talent Build your employer brand Advertising Reach developers & technologists worldwide; Labs The future of collective knowledge sharing; About the company Sep 23, 2014 · By default for concat the original index values will be used and will just stack the dfs after each other. DataFrame(c, index=bw. end)] # date data_x data_y start end. Your merge argument says that the column "Player" is in df2 however it is not. date_range('1/1/2000', periods=4, freq='10min') Aug 13, 2018 · Index-Index Merge: Set left_index and right_index to True or use on and use how. hzdept_r hzdepb_r sandtotal_r. left: use only keys from left frame, similar to a SQL left outer join I have a dataframe, grouped, with multiindex columns as below: import pandas as pd import numpy as np import random codes = ["one","two","three&quot;]; colours = [&quot;bl May 27, 2013 · The only way I know of to preserve indices across a merge is for the merge to involve an index on at least one of the data frames being merged. I would like to merge those 2 dataframes by row so that each index from each dataframe being the same combines the corresponding rows from b Feb 2, 2022 · You can merge dataframes on two columns. Process finished with exit code 0. I have several similarly structured pandas dataframes stored in a dictionary. 'X_x, 'X_y' etc. org General functions. concat but it doesn't seem to work. In your case however you will need to match the time zones of your indices first, one is UTC We can rename the axis to have a common index name, I tried playing around with merging on a blank index but I couldn't figure it out, we then merge on your 'loc' column + newly named 'date' index. May 15, 2019 · Stack Overflow Public questions & answers; Stack Overflow for Teams Where developers & technologists share private knowledge with coworkers; Talent Build your employer brand Jun 29, 2016 · I have a list of data frames and I need to merge them together using a unique column (date). NaNs result in the index type being upcasted to float. DataFrame の join() メソッドも使える。. merge(): Exists both as a top-level pandas function and a DataFrame method (as of pandas 1. Oct 10, 2016 · I want to perform a merge in pandas on more than one column, where one of the columns is an index column. Mar 22, 2023 · Assuming df1 and df2 the inputs, simply assign to the last duplicate:. I think you may just need to reset the index on df2. Merging Pandas DataFrames on MultiIndex column values. Use swifter to parallel, speed up and visualize default apply function (with colored progress bar) Use OrderedDict from collections to get rid of duplicates in the output of merge and keep the initial order. . assign(dummy=1). But I want the column names to stay the same, and the data to be updated if it already exists. merge(rates_gp. Parameters: rightDataFrame or named Series. un qb ph sy im rz mw zr be wj