Xarray reindex. Parameters: dim (mapping of hashable to .

Xarray reindex Dataset(variables=None, coords=None, attrs=None) ¶ A multi-dimensional, in memory, array database. I have tried to do this using ds. reindex_like(other, *, method=None, tolerance=None, copy=True, fill_value=<NA>) [source] # Conform this object onto the indexes of another object, for indexes which the objects share. reindex(indexers=None, method=None, tolerance=None, copy=True, fill_value=<NA>, **indexers_kwargs) unit-aware version of reindex Like xarray. Parameters: other (Dataset or DataArray) – Object with an ‘indexes’ attribute giving a xarray’s reindex, reindex_like and align impose a DataArray or Dataset onto a new set of coordinates corresponding to dimensions. Reshaping and reorganizing data # Reshaping and reorganizing data refers to the process of changing the structure or organization of data by modifying dimensions, array shapes, order of values, or indexes. tickers. Fix open_mfdataset with engine='pynio' (GH936). This seems to sort the coordinates/dimen Indexing and selecting data ¶ Similarly to pandas objects, xarray objects support both integer and label based lookups along each dimension. Conform this object onto a new set of indexes, filling in missing values with fill_value. Parameters indexers (dict, optional) – Dictionary with keys given by dimension names and values given by arrays of Oct 6, 2025 · xarray. Parameters: indexers (dict, optional) – Dictionary with keys given by dimension names and values given by arrays of coordinates Oct 6, 2025 · xarray. Index [source] # Base class inherited by all xarray-compatible indexes. Parameters: indexers (dict, optional) – Dictionary with keys given by dimension names and values given by arrays Feb 16, 2025 · What happened? The lazy computation time seems to be dependent on the indexers size in Dataset. Mar 1, 2025 · Conform this object onto a new set of indexes, filling in missing values with fill_value. indexes # property DataArray. indexes # Mapping of pandas. Dataset ¶ class xray. When taking the difference between t Aug 5, 2022 · What happened? After applying the concat function to a dataset with a Multiindex, a lot of functions related to indexing are broken. In either case, a new xarray object is always returned. However, xarray objects also have named dimensions, so you can optionally use dimension names instead of relying on the positional ordering of dimensions. limit (int or None, default: None) – The maximum number of consecutive NaN values to forward fill. tolerance and fill_value are not supported, yet. Apr 10, 2020 · 本文使用之前文章《xarray指南：索引和选择数据 - 位置和名称索引》中的示例数据，不再重复介绍。 Feb 24, 2019 · Indeed starting from a pure NumPy array in this case is a little more cumbersome; see my latest update. import x Oct 6, 2025 · xarray. . reindex_like ¶ Dataset. xray. Parameters: target (an iterable) method ({None, 'pad'/'ffill', 'backfill'/'bfill', 'nearest'}, optional) – default: exact matches only. reindex_like # DataArray. Nov 1, 2025 · xarray. DataFrame methods of the same name, although they in xarray they always create new dimensions rather than adding to the existing index or columns. ) Below I will assume that da is the name of the original dataarray import numpy as np # get unique ticker values as numpy array unique_tickers = np. Calculating temp0 is Oct 6, 2025 · xarray. Parameters: objs (sequence of Dataset and DataArray) – xarray objects to concatenate together. Mar 20, 2021 · I have two xArray dataarrays that indexed by datetime64 and contain a single feature: a list containing a single string. reindex(indexers=None, method=None, tolerance=None, copy=True, fill_value=<NA>, **indexers_kwargs) [source] # Conform this object onto a new set of indexes, filling in missing values with fill_value. Instead, we create a lazy array that supports any number of further differed indexing operations. The alternative design would be to append an array of all NaNs along one axis, but on average I think the current implementation is faster and results in more contiguous chunks -- it's quite common to intersperse missing indices with reindex () and alternating Jan 3, 2025 · Xarray’s reindex, reindex_like and align impose a DataArray or Dataset onto a new set of coordinates corresponding to dimensions. See parameters, methods, and examples of reindexing with xarray. g. Query the index with another index of the same type. set_index(indexes=None, append=False, **indexes_kwargs) [source] # Set DataArray (multi-)indexes using one or more existing coordinates. fill_value (scalar or dict-like, optional) – Value to use for newly missing values. Oct 6, 2025 · If copy=False and reindexing is unnecessary, or can be performed with only slice operations, then the output may share memory with the input. set_index # Dataset. apply_func() here? Xarray’s reindex, reindex_like and align impose a DataArray or Dataset onto a new set of coordinates corresponding to dimensions. As xarray objects can store coordinates corresponding to each dimension of an array, label-based Oct 6, 2025 · If copy=False and reindexing is unnecessary, or can be performed with only slice operations, then the output may share memory with the input. Learn how to conform a DataArray onto a new set of indexes, filling in missing values with NaN. reindex unmodified. I would like to sort the coordinates and variables of an xarray Dataset in alphabetical order. One option that works currently would be to determine the proper grid (e. To do this systematically in xarray, we would want to update xarray. reindex DataArray. 3 days ago · xarray. Parameters: indexers (dict, optional) – Dictionary with keys given by dimension names and values given by arrays of coordinates Xarray's reindex, reindex_like and align impose a DataArray or Dataset onto a new set of coordinates corresponding to dimensions. Xarray provides several methods to accomplish these tasks. align to be capable of approximate alignment. stack # Dataset. The times in the new time series are a strict subset of the larger. This is true even if you aren't using dask. set_xindex. CFTimeIndex. Nov 8, 2023 · Is there a clean way in Xarray to reindex or a DataArray based on a 2D coordinate like local_time below, without resorting to manual index manipulation, potentially leveraging Xarray's built-in functions? I provide code for mock input data and show my desired result after outlining my motivation. Oct 6, 2025 · xarray. Computing with Multiple Objects # Learning goals: Perform operations across multiple datasets Understand two important concepts: broadcasting and alignment. reindex # Dataset. Implementation is optional but required in order to support alignment. PandasMultiIndex'>, **dim_kwargs) [source] # Stack any number of existing dimensions into a single new dimension. Oct 26, 2022 · I have two datasets, where they share a coordinate. Jan 3, 2025 · API reference # This page provides an auto-generated summary of xarray’s API. MultiIndex respectively. Apr 15, 2024 · What is your issue? Reindexing a dataset without loading it into memory seems to be very slow (about 1000x slower than reindexing after loading into memory). They will be passed through to DataArray. (See xarray docs on reindexing. See set_xindex() for setting a pandas or a custom Xarray-compatible index from one or more arbitrary coordinates Xarray’s reindex, reindex_like and align impose a DataArray or Dataset onto a new set of coordinates corresponding to dimensions. By padding the small array with zeros, this approach enables in-place addition, but with the cost of a lot of unnecessary allocation. reindex(method=None, tolerance=None, copy=True, **indexers) ¶ Conform this object onto a new set of indexes, filling in missing values with NaN. Like DataFrame. Every subclass must at least implement Index. Jul 30, 2024 · Xarray’s reindex, reindex_like and align impose a DataArray or Dataset onto a new set of coordinates corresponding to dimensions. Indexing and selecting data ¶ xarray offers extremely flexible indexing routines that combine the best features of NumPy and pandas for data selection. In either case, new xarray objects are always returned. See set_xindex() for setting a pandas or a custom Xarray-compatible index from one or more arbitrary Aug 31, 2016 · When you index a variable loaded from a netCDF file, xarray doesn't load it into memory immediately. Thus in total, xarray supports four different kinds of indexing, as described below and summarized I agree that this would be useful. pint. Raises an error if this Dataset has indexes xarray. Oct 19, 2023 · The Index base class # Every Xarray index must inherit from the Index base class. They contain an introduction to Xarray’s main concepts and links to additional tutorials. The original values are subset to the index labels still found in the new labels, and values corresponding to new labels not found in the original object are in-filled with NaN. Xarray indexes are created exclusively from subclasses of Index, mostly via Xarray’s public API like Dataset. API reference # This page provides an auto-generated summary of xarray’s API. Xarray’s reindex, reindex_like and align impose a DataArray or Dataset onto a new set of coordinates corresponding to dimensions. reindex(), except the object’s indexes are converted to the units of the indexers first. _getitem_with_mask for the implementation on the xarray side. Do not use this class directly for creating index objects. What's reputation and how do I get it? Instead, you can save this post to reference later. assign()(see also Dictionary like methods),, add variables from other datase Oct 6, 2025 · Reshaping and reorganizing data # Reshaping and reorganizing data refers to the process of changing the structure or organization of data by modifying dimensions, array shapes, order of values, or indexes. xarray. values) da_reindexed = da. 16 ms Reindexing the Small Array If we can’t do fast in-place addition with automatic alignment, let’s instead try to manually align the small array to match the large array with reindex_like. unique(da. set_index(indexes=None, append=False, **indexes_kwargs) [source] # Set Dataset (multi-)indexes using one or more existing coordinates or variables. from_variables(). Something like dataset. Here is a minimum working example: time Jan 2, 2025 · Xarray’s reindex, reindex_like and align impose a DataArray or Dataset onto a new set of coordinates corresponding to dimensions. These methods are particularly useful for reshaping xarray objects for use in machine learning packages, such as scikit-learn, that Jan 2, 2025 · Xarray’s reindex, reindex_like and align impose a DataArray or Dataset onto a new set of coordinates corresponding to dimensions. In other words, if there is a gap with more than this Aug 8, 2016 · Very simple question but I can't find the answer online. Feb 23, 2022 · I got an error: cannot reindex or align along dimension 'latitude' because the index has duplicate values. Sep 3, 2017 · From a discussion in #1473 comment It would be convenient if we have multi-dimensional reindex method, where we consider dimensions and coordinates of indexers. unit-aware version of reindex. Index and pandas. Index objects used for label based indexing. Any mismatched coordinate values will be filled in with NaN, and any mismatched dimension names will simply be ignored. A similar discussion can be found here. ffill(dim, limit=None) [source] # Fill NaN values by propagating values forward Requires bottleneck. I know about mer Oct 6, 2025 · xarray. Parameters: other (Dataset or DataArray) – Object with an ‘indexes’ attribute giving a Nov 5, 2025 · xarray. I want to merge the two dataset, so that the second set is also indexed by the stacked coordina Oct 6, 2025 · xarray. For example, it is not possible to apply reindex_like to itself Clarified copy argument for reindex() and align(), which now consistently always return new xarray objects (GH927). reindex(indexers=None, method=None, tolerance=None, copy=True, fill_value=<NA>, **indexers_kwargs)[source] # Conform this object onto a new set of indexes, filling in missing values with fill_value. Index. Index # class xarray. Like xarray. Missing values are filled with fill_value. Returns: dim_positional_indexers (dict) – A dictionary where keys are dimension names and values are positional indexers. open_mfdataset # xarray. concat # xarray. add ( {"new_array": new_data_array}). See also: What parts of xarray are considered public API? Top-level functions # Aug 31, 2016 · When you index a variable loaded from a netCDF file, xarray doesn't load it into memory immediately. Parameters: other (Index) – The other Index object used to query this index. reindex(target, method=None, level=None, limit=None, tolerance=None) [source] # Create index with target’s values. However, manual alignment can be useful for greater control and for increased performance. If combine=’by_coords’ then the function combine_by Jul 1, 2025 · Conform this object onto a new set of indexes, filling in missing values with fill_value. These methods are particularly useful for reshaping xarray objects for use in machine learning packages, such as scikit-learn, that xarray. See set_xindex() for setting a pandas or a custom Xarray-compatible index from one or more arbitrary Oct 22, 2025 · If copy=False and reindexing is unnecessary, or can be performed with only slice operations, then the output may share memory with the input. Dataset. But, in the first set that coordinate is stacked. Minimal Complete xarray. Do you think you could find a way to generate the length-365 array such that it was already appropriately labeled with dates from 2001 and in the form of a DataArray? Then all you would need is the reindexing step before passing it to where. Whether data is a copy or a view is more predictable in xarray than in pandas, so unlike pandas, xarray does not produce SettingWithCopy warnings. You'll need to complete a few actions and gain 15 reputation points before being able to upvote. They are of different lengths, and I want to reindex one to match the indice Nov 5, 2025 · ,, How do I…, Solution,,, add a DataArray to my dataset as a new variable, my_dataset[varname] = my_dataArray or Dataset. Nov 5, 2025 · xarray. Dataset implements the mapping interface with keys given by variable names and values given by Align and reindex ¶ xray’s reindex, reindex_like and align impose a DataArray or Dataset onto a new set of coordinates corresponding to dimensions. I have a Dataset and I just want to add a named DataArray to it. Align and reindex ¶ xray’s reindex, reindex_like and align impose a DataArray or Dataset onto a new set of coordinates corresponding to dimensions. reindex # DataArray. Feb 24, 2019 · Indeed starting from a pure NumPy array in this case is a little more cumbersome; see my latest update. Variable. backfill / bfill: use NEXT index value Oct 19, 2023 · New to xarray? Check out the getting started guides. reindex_like(other, method=None, tolerance=None, copy=True) ¶ Conform this object onto the indexes of another object, filling in missing values with NaN. reindex(indexers=None, *, method=None, tolerance=None, copy=True, fill_value=<NA>, **indexers_kwargs) [source] # Conform this object onto the indexes of another object, filling in missing values with fill_value. Xarray operations that combine multiple objects generally automatically align their arguments to share the same indexes. If a dict-like maps variable names to fill values. Reshaping and reorganizing data ¶ These methods allow you to reorganize Mar 18, 2019 · It sounds like you want to reindex your dataarray. As xarray objects can store coordinates corresponding to each dimension of an array, label-based May 7, 2023 · By doing a concat, you’re telling xarray you want a single array, and it has to figure out how to do things (maybe you want join="override"?) It’s also worth asking if you even need to align things in the first place. The most basic way to access elements of a DataArray object is to use Python’s [] syntax, such as array[i, j], where i and j are both integers. reindex_like(other) [source] # Query the index with another index of the same type. Parameters indexers (dict, optional) – Dictionary with keys given by dimension names and values given by arrays of coordinates tick xarray. The proposed outline by @shoyer is G Conform this object onto a new set of indexes, filling in missing values with fill_value. In xarray, I have a larger time series that I want to replace some of the values with what is in a smaller time series. A dataset resembles an in-memory representation of a NetCDF file, and consists of variables, coordinates and attributes which together form a self describing dataset. core. DataArray. reindex. Parameters indexers (dict, optional) – Dictionary with keys given by dimension names and values given by arrays of coordinates tick Mar 1, 2025 · Conform this object onto a new set of indexes, filling in missing values with fill_value. The default fill value is NaN. transpose(*sorted(ds. For more details and examples, refer to the relevant chapters in the main part of the documentation. indexes (dict-like, optional) – Any indexes explicitly provided with the indexes argument should be used in preference to the aligned indexes. reindex(indexers=None, *, method=None, tolerance=None, copy=True, fill_value=<NA>, **indexers_kwargs)[source] # Conform this object onto the indexes of another object, filling in missing values with fill_value. concat(objs, dim, data_vars=all, coords=different, compat=equals, positions=None, fill_value=<NA>, join=outer, combine_attrs='override', create_index_for_new_dim=True) [source] # Concatenate xarray objects along a new or existing dimension. Like the situation in the discussion, the data I was trying to read has missing values, so why do the missing value issue raise duplicate values error? These methods are modeled on the pandas. Parameters: dim (mapping of hashable to Apr 10, 2020 · 本文使用之前文章《xarray指南：索引和选择数据 - 位置和名称索引》中的示例数据，不再重复介绍。 Mar 1, 2025 · Xarray’s reindex, reindex_like and align impose a DataArray or Dataset onto a new set of coordinates corresponding to dimensions. Calculating temp0 is Mar 29, 2023 · What happened? I am trying to use xarray's smart broadcasting to do computation with two DataArrays, one of which has two indexes set for one of its dimensions. reindex ¶ DataArray. If it is straightforward to generate the result with numpy, would it be possible to use xarray. Jun 1, 2025 · Conform this object onto a new set of indexes, filling in missing values with fill_value. New dimensions will be added at the end, and by default the corresponding coordinate variables will be combined into a MultiIndex. open_mfdataset(paths, chunks=None, concat_dim=None, compat=no_conflicts, preprocess=None, engine=None, data_vars=all, coords=different, combine='by_coords', parallel=False, join=outer, attrs_file=None, combine_attrs='override', errors='raise', **kwargs) [source] # Open multiple files as a single dataset. set_index # DataArray. This explains the surprising performance you observe. Parameters: indexers (dict, optional) – Dictionary with keys given by dimension names and values given by arrays of Jul 3, 2020 · Xarray - InvalidIndexError: Reindexing only valid with uniquely valued Index objects Asked 5 years, 4 months ago Modified 5 years, 3 months ago Viewed 3k times Sep 7, 2022 · Minimal Complete Verifiable Example import numpy as np import pandas as pd import xarray as xr def map_coords (ds, *, name, mapping): """ Takes a xarray dataset's coordinate values and updates them with the given the provided mapping. Upvoting indicates when questions and answers are useful. Parameters: indexers (dict, optional) – Dictionary with keys given by dimension names and values given by arrays of coordinates Indexing and selecting data ¶ xarray offers extremely flexible indexing routines that combine the best features of NumPy and pandas for data selection. reindex_like # Index. Parameters: dim (Hashable) – Specifies the dimension along which to propagate values when filling. If copy=False and reindexing is unnecessary, or can be performed with only slice operations, then the output may share memory with the input. stack(dim=None, create_index=True, index_cls=<class 'xarray. array (triggered by setting chunks= in open_dataset or using open_mfdataset). These methods are particularly useful for reshaping xarray objects for use in machine learning packages, such as scikit-learn, that Feb 5, 2019 · See xarray. Each object is expected to consist Parameters: indexers (dict, optional) – Dictionary with keys given by dimension names and values given by arrays of coordinates tick labels. indexes. reindex(tickers=unique_tickers) Xarray’s reindex, reindex_like and align impose a DataArray or Dataset onto a new set of coordinates corresponding to dimensions. See also: What parts of xarray are considered public API? Top-level functions # Indexing and selecting data ¶ xarray offers extremely flexible indexing routines that combine the best features of NumPy and pandas for data selection. dims)). One of indexers or indexers_kwargs must be provided. It is for example the case of Xarray built-in PandasIndex and PandasMultiIndex subclasses, which wrap pandas. However, you should still avoid assignment with chained indexing. This legacy method is limited to pandas (multi-)indexes and 1-dimensional “dimension” coordinates. copy (bool, optional) – If copy=True, data in the return value is always Jan 12, 2024 · 文章浏览阅读3k次，点赞33次，收藏30次。Xarray提供了极其灵活的索引例程，结合了NumPy和pandas在数据选择方面的最佳特性。访问DataArray对象元素的最基本方法是使用Python的 []语法，比如array [i，j]，其中I和j都是整数。由于xarray对象可以存储与数组的每个维度相对应的坐标，所以基于标签的索引类似于 Oct 8, 2024 · My proposal is that Xarray (not sure if this would be something better on the Dask side but they do not handle indexes as Xarray) could handle the alignment of the chunks in a more "sophisticated" way, it can be through a heuristic that decides the "ideal chunks" of the output, for example, use the biggest chunk of all the arrays as output, and add artificial data before reindexing (probably Query the index with another index of the same type. ffill # DataArray. Apr 6, 2025 · Time: 102 ms ± 2. Similarly to pandas objects, xarray objects support both integer and label based lookups along each dimension. , from one file) and then use the preprocess argument of open_mfdataset to reindex() each dataset to the desired grid. reindex # CFTimeIndex. Nov 8, 2023 · Reindex on a coordinate dependent on two dimensionsHmm not sure how this would work using Xarray's reindexing machinery, which works along existing dimensions whereas in the example above the dimensions change from the input to the desired output (utc_time -> local_time). What did you expect to happen? Close to constant time with lazy reindexing. unstack, xarray’s unstack always succeeds, even if the multi-index being unstacked does not contain all possible levels. pad / ffill: find the PREVIOUS index value if no exact match. Sep 4, 2025 · xarray. tknj ugbea urrnaa aib rnheh jcbvjm ueadwiq zgmc ulylk rwlw gpnh yts uak avdhz yetv